Test Overview of Organic Acid Test Panel (OAT)

The Organic Acid Test (OAT) Panel examines metabolites in a patient's urine that are products of body metabolism and gut microbes. It can reveal imbalances in metabolic pathways, nutritional imbalances, and abnormal microbial overgrowth in the small and large intestines. The OAT Panel complements the Comprehensive Digestive Stool Analysis Panel, which can reveal abnormal microbial overgrowth in the large intestine.

Test Indications of Organic Acid Test Panel (OAT)

According to Go to That's HealthThat's Health, OAT indications include:
  • First-line test for evaluating Autism Spectrum Disorder (ASD), Pervasive Developmental Delay (PDD), Asperger's Syndrome, Attention-Deficit Hyperactivity Disorder (ADD, ADHD), learning disability, depression, anxiety, other mood disorders, Small Intestinal Bacteria Overgrowth (SIBO), and environmental toxicity,
  • Seizure disorders,
  • Chronic Fatigue Syndrome,
  • Methyl-tetrahydrofolate reductase (MTHFR) deficiency.

Theory of Organic Acid Test Panel (OAT)

Brief overview of Biochemistry

All cellular life is based on chemical reactions from microscopic "factories" called enzymes. The DNA of every cell contains a blueprint for how these enzymes are to be constructed from basic raw materials like amino acids found in the protein we eat.

As with real-world factories, enzymes are specialized to do different things. Just as a "shoe factory" takes in raw materials such as leather and thread and delivers shoes, enzymes take in raw materials in the form of chemicals and provide products that are different chemicals. The ebb and flow of all these chemicals processed by enzymes are called metabolism and create life.

Doctors are interested in these chemicals flowing through our cells because they can help diagnose diseases and imbalances and illuminate appropriate therapies to correct them. Fortunately, many of these chemicals, called organic acids, can be collected in the patient's urine and analyzed using the Organic Acid Test.

As with factories, there are thousands of different kinds of enzymes, each specializing in converting specific input materials into specific output materials. We often refer to input materials as substrates or precursors and output materials as products or metabolites. However, since the outputs of one enzyme become the inputs to the following enzyme, these terms may refer to the same chemical substance depending on the context.

In addition to the primary substance being processed by an enzyme, we often identify additional small molecules that act as "helpers." We call these substances cofactors. Typically, vitamins and minerals are considered to be cofactors. Think of them like "shop supplies" that are necessary but not primary input substrates.

Most of the time, all our enzymes hum along together, maintaining a healthy balance of all the chemical reactions of life. However, when something goes wrong, you see the doctor to identify the problem and its solution. What can go wrong?

  • Missing cofactors - Inadequate or imbalanced intake of vitamins and minerals.
  • Unhelpful bacteria, yeasts, and fungi in your gut - This is called dysbiosis and can confuse our enzymes by making chemical substances that "sort of look like" our enzyme's normal substrates but cannot be processed by our enzymes but instead "clog up" the system. These are called analogues. They are also called competitive inhibitors because they act like pallets of defective raw materials piled up on the factory's loading dock, blocking access to the proper input materials.
  • Competitive inhibition - A factory can sometimes process several similar products, depending on the available inputs. For example, a factory might make gloves out of soft leather or shoes out of tough leather. When there is lots of soft leather and not so much tough leather, the factory might busy its machines mostly making gloves, leaving little machine time to make shoes. This is an example of competitive inhibition of shoe-making. The same is true of enzymes.
  • Supply chain problems - Like real factories, many suppliers must work together to deliver the ultimate product. Miners deliver coal and iron ore to a factory that makes sheet metal; the sheet metal goes to a factory that shapes the metal into a car body; other suppliers provide transmissions, computers, radiators, etc. If anything shuts down one step, for example, the sheet metal factory, the whole supply chain grinds to a halt - coal and ore pile up with no place to store it, and the body factory is idled because it has no raw materials. We see the same problems with chains of enzymes in the body.
  • Contextual regulation - A factory may increase its production rate if its management foresees an extra supply of inputs, adopting the adage of "make hay while the sun shines." On the other hand, a factory may decrease its production rate if its management foresees a reduction of future demand (e.g., unsold cars are accumulating on dealer lots). In the microscopic world of enzymes, this is called allosteric regulation - an increased supply of input substrates reshapes the enzyme to work harder (allosteric activation). In contrast, the build-up of output substrates reshapes the enzyme to work slower (allosteric inhibition).
  • Covalent modification of enzyme structure - is an extreme form of allosteric regulation in which cofactors (e.g., phosphate) are added to or removed from the enzyme to activate or inhibit its activity.
  • Le Châtelier's principle (Law of Mass Action) - Many (but not all) enzymes work in both directions; in these cases, increases in reactant titers favor the forward reaction. In contrast, increases in product titers favor the reverse reaction [cite needed].
  • Epigenetic Regulation - DNA is divided into chunks called genes. Different chunks of DNA serve as blueprints for different enzymes. Various environmental factors in the body can induce more copies of a particular enzyme to be made, thereby increasing its activity. Conversely, other environmental factors can suppress the number of copies of an enzyme made, thereby slowing its activity.
  • DNA problems - A problem (called an SNP) in your DNA creates enzymes that "work differently" - this is called an inborn error of metabolism. This is rare. In many cases, the problem can be mitigated by careful adjustment to nutrition.

While this all sounds complicated, the good news is that the Organic Acid Test gives us an inside look at the dynamics of this microscopic biochemical world - we just have to know how to interpret it. The rest of this monograph will focus on just that.

Yeast/Fungal Metabolites

Elevated yeast/fungal metabolites suggest a yeast or fungal overgrowth in the gastrointestinal tract [GP2010].

Citramalic (Methylmalic) Acid

  • Citramalic acid is a byproduct of a Saccharomyces yeast or Propionibacterium species and suggests dysbiosis Go to MosaicDXMosaicDX.
  • As an analogue of the Krebs cycle compound malic acid, it may interfere with the production of malic acid in the Krebs cycle.
  • Consider treating with probiotics and other naturopathic techniques.

5-Hydroxymethyl-2-furoic Acid

  • 5-hydroxymethyl-2-furoic acid is a byproduct of the fungus Aspergillus and probably other fungi and yeast species, suggesting dysbiosis.
  • Consider treating with antifungals, probiotics, and naturopathic techniques. Also, consider testing for urine mycotoxins [Mosaic2024].

3-Oxoglutaric Acid

  • 3-Oxoglutaric acid is an analogue of the Krebs cycle compound 2-oxoglutaric (alpha-ketoglutaric) acid.
  • Elevated titers suggest yeast overgrowth in the GI tract Go to MosaicDXMosaicDX.
  • Slightly elevated titers are found in autism and other disorders.
  • Elevated 3-oxoglutaric acid may correlate with low 2-oxoglutaric acid, indicating an interference with 3-oxoglutaric acid in the Krebs cycle.
  • It can be formed from the amino acids lysine and tryptophan.
  • Consider treating with probiotics and other naturopathic techniques.

Furan-2,5-dicarboxylic Acid

  • Furan-2,5-dicarboxylic acid is a byproduct of the fungus Aspergillus and probably other fungi and yeast species, suggesting dysbiosis.
  • Consider treating with antifungals, probiotics, and naturopathic techniques. Also, consider testing for urine mycotoxins [Mosaic2024].

Furancarbonylglycine

  • Furancarbonylglycine is a conjugate of furancarboxylic acid and the amino acid glycine produced by Aspergillus and possibly other fungal species, which suggests dysbiosis.
  • Consider treating with antifungals, probiotics, and naturopathic techniques. Also, consider testing for urine mycotoxins [Mosaic2024].

Tartaric Acid (3-Hydroxymalic Acid or 2,3-Hydroxy-succinic acid)

  • Tartaric acid is an analogue of the Krebs cycle intermediate malic acid that inhibits the Krebs cycle enzyme fumarase that converts fumaric acid to malic acid [Shaw2008].
  • It is a toxic fermentation product of Saccharomyces yeast [need citation].
  • It is a product of Candida hyaluronidase that damages muscles and kidneys [Robertson1968  🕮 ], Go to MosaicDXMosaicDX.
  • It is also found in grapes, cream of tartar, and as a food additive.
  • High titers are associated with autism and fibromyalgia [Shaw2008].
  • The FDA generally Recognizes Tartaric Acid as safe (GRAS) in low doses, but a 12 g dose may be fatal [Shaw2008].
  • Consider treating with antifungals, probiotics, and naturopathic techniques. Also, consider testing for urine mycotoxins [Mosaic2024].

Arabinose

  • Arabinose is a product of Candida hyaluronidase and damages muscles and kidneys [Robertson1968  🕮 ], Go to MosaicDXMosaicDX.
  • Arabinose is a metabolite produced in the liver from arabitol (also called arabinitol); arabitol is produced by various yeast species such as Candida albicans, Candida tropicalis, Candida parapsilosis, etc. [need Citaton].
  • Arabinose is a 5-carbon aldose sugar that is not made in significant quantity by human metabolism but can be found in apples, grapes, and pears and can serve as a marker for yeast overgrowth [Kiehn1979  🕮 ], [Wong1990  🕮 ], [Larsson1994  🕮 ], [Roboz1992  🕮 ].
  • Arabinose may be a particular problem for patients with a defect in their pentose metabolism; this defect can be tested for [Shaw2008].
  • Consider treating with antifungal pharmaceuticals, probiotics, and other naturopathic techniques.

Carboxycitric Acid

  • Carboxycitric acid is a byproduct released from mycotoxins called fumonisins in the gastrointestinal tract Go to MosaicDXMosaicDX.
  • Carboxycitric acid is an analogue of the Krebs cycle compound citric acid; as such, it may interfere with the metabolism of citric acid in the Krebs cycle.
  • Elevated titers of yeast/fungal metabolites suggest dysbiosis Go to MosaicDXMosaicDX.
  • Fumonisins are produced primarily by Fusarium verticillioides, a plant parasite. Elevated titers can be caused by eating contaminated corn [Brown2007  🕮 ].
  • Consider treating with antifungal pharmaceuticals, probiotics, and other naturopathic techniques.

Bacterial Metabolites

Hippuric Acid

  • Hippuric acid is a conjugate of benzoic acid and glycine formed in the liver as part of the normal phase-II detoxification pathway [need cite] and is a bacterial product of phenylalanine metabolism Go to MosaicDXMosaicDX.
  • Titers may be elevated due to bacteria overgrowth of the GI tract producing benzoic acid; other sources of benzoic acid are the solvent toluene, the food preservative sodium benzoate, apples, pears, tea, coffee, sunflower seeds, carrots, blueberries, cherries, potatoes, tomatoes, eggplant, sweet potatoes, peaches [GP2010].
  • Low titers of hippuric acid may be due to depletion of glycine due to competing detoxification reactions or low amounts of bacteria after antibiotic use.
  • Consider treating with probiotics such as Lactobacillus rhamnosus and other naturopathic techniques [GP2010].

2-Hydroxyphenylacetic Acid

  • 2-Hydroxyphenylacetic acid is produced by the overgrowth of several species of bacteria in the GI tract by metabolizing the amino acid tyrosine.
  • Elevated titers are associated with PKU [GP2010].
  • Very elevated titers are present in celiac disease and enteritis.
  • Consider treating with probiotics and other naturopathic techniques [GP2010].

4-Hydroxybenzoic Acid (p-Hydroxybenzoic acid)

  • Elevated titers of 4-Hydroxybenzoic acid may be due to bacterial overgrowth or may be due to fruits such as blueberries [GP2010].
  • 4-Hydroxybenzoic acid is also a metabolite of parabens in food, cosmetics, and toiletries. Parabens have estrogenic activity and may be associated with breast cancer [GP2010], [Routledge1998]. Parabens may uncouple oxidative phosphorylation, leading to mitochondrial dysfunction [GP2010].
  • Treatment is by avoidance of parabens.

4-Hydroxyhippuric Acid (p-Hydroxyhippuric Acid)

  • Elevated titers of 4-Hydroxyhippuric acid may be due to bacterial overgrowth or may be due to fruits such as blueberries [GP2010].
  • 4-Hydroxyhippuric acid is also a metabolite of parabens in food, cosmetics, and toiletries. Parabens have estrogenic activity and may be associated with breast cancer [GP2010], [Routledge1998]. Parabens may uncouple oxidative phosphorylation, leading to mitochondrial dysfunction [GP2010].
  • Treatment is by avoidance of parabens.

Dihydroxyphenylpropionic Acid (DHPPA)

  • DHPPA is a metabolite of chlorogenic acid in many fruits and vegetables Go to MosaicDXMosaicDX.
  • Chlorogenic acid is metabolized to DHPPA by commensal bacteria such as Lactobacilli, Bifidobacteria, and Escherichia coli; therefore, DHPPA is a marker for beneficial gut microbiome Go to MosaicDXMosaicDX.

Phenylcarboxylic Acids

  • Elevated titers of phenylcarboxylic acids suggest the overgrowth of GI bacteria.
  • [Dr. Weyrich notes this is not a single compound - the carboxylic acid can be acetic acid (yielding phenylacetic acid) or any other carboxylic acid].

Indole-like Compound Acids

  • Indole-like compound acids are most likely derived from tryptophan.
  • Elevated titers suggest the overgrowth of GI bacteria, which are commonly elevated along with 3-indoleacetic acid [need cite].

Clostridia Bacterial Markers

4-Hydroxyphenylacetic Acid

  • 4-Hydroxyphenylacetic acid is produced by the overgrowth of bacteria in the GI tract by metabolizing the amino acid tyrosine Go to MosaicDXMosaicDX.
  • Elevated titers are associated with Clostridia overgrowth, small intestinal bowel overgrowth (SIBO), or small bowel disease Go to MosaicDXMosaicDX.
  • Very elevated titers are present in celiac disease, enteritis, and intestinal resection.
  • Treatment with the antibiotic neomycin can significantly lower urine titers; also consider naturopathic therapies.

3-(3-Hydroxyphenyl)-3-hydroxypropionic acid (HPHPA)

  • HPHPA is produced by Clostridium species, including but not limited to Clostridium difficile [GP2010], Clostridium sporogenes Go to MosaicDXMosaicDX, Clostridium botulinum Go to MosaicDXMosaicDX, Clostridium caloritolerans Go to MosaicDXMosaicDX, Clostridium mangenoyi [also known as Clostridioides mangenoyi], Clostridium ghoni, Clostridium bifermentans [also known as Paraclostridium bifermentans], and Clostridium sordellii [GP2010].
  • HPHPA inhibits the enzyme dopamine-beta-hydroxylase, leading to derangement of neurotransmitter balance.
  • Elevated titers are common in autism, depression, schizophrenia, seizures, chronic fatigue syndrome, colitis, tic disorders, and muscle weakness or paralysis [Shaw2008], [GP2010] (particularly when its level exceeds 500mmol/mol creatinine) [GP2010] Go to MosaicDXMosaicDX.
  • Antibiotics such as vancomycin or metronidazole (Flagyl) can significantly lower the HPHPA level in urine [GP2010]. Adding probiotics such as Lactobacillus acidophilus GG, Lactobacillus rhamnosus [also known as Lacticaseibacillus rhamnosus], or Saccharomyces boulardii is also recommended [Shaw2008], [GP2010]; also consider naturopathic treatments.
  • According to [Shaw2008, pg 14], Clostridium spp. deaminate the amino acid phenylalanine (which is the precursor of the important neurotransmitters dopamine, norepinephrine, and epinephrine) to make 3-phenylpropionic acid, which is then hydroxylated in the meta position by Clostridium spp. to make 3-(3-hydroxyphenyl)-propionic acid [Elsden1976  🕮 ] [Bhala1993  🕮 ]. This intermediate is then subjected to human beta-oxidation to form 3-(3-hydroxyphenyl)-3-hydroxypropionic acid (HPHPA), which is detectable in the urine.
  • An alternative pathway for the formation of HPHPA from phenylalanine is via microbial meta-hydroxylation of phenylalanine to form 3-hydroxyphenylalanine (an analogue of tyrosine, which is 4-hydroxyphenylalanine), which is then deaminated to form 3-(3-hydroxyphenyl)-propionic acid, which then proceeds to HPHPA as above [Shaw2008].

4-Cresol

  • An elevated titer of 4-cresol suggests an overgrowth of Clostridium difficile in the GI tract Go to MosaicDXMosaicDX.
  • 4-Cresol is often elevated in autism, psychiatric disorders, and GI disorders Go to MosaicDXMosaicDX.
  • 4-Cresol inhibits the enzyme dopamine-beta-hydroxylase, causing derangement of neurotransmitter balance Go to MosaicDXMosaicDX.

Vanillylmandelic Acid (VMA) Analogue

  • VMA is a metabolite of the amino acid tyrosine produced by Clostridium species.
  • Clostridial overgrowth may interfere with the body's production and metabolism of the neurotransmitters dopamine and norepinephrine, which are made from tyrosine.
  • Elevated titers are common in autism, depression, schizophrenia, seizures, and chronic fatigue syndrome.
  • Treatment with the antibiotics vancomycin or metronidazole (Flagyl) can significantly lower titers in urine; also consider naturopathic therapies.

Oxalate Related Metabolites

Glyceric Acid

  • Elevated titers of glyceric acid are associated with autism, vulvar pain, and fibromyalgia [GP2010].
  • Elevated titers may be due to microbial sources such as yeast (Aspergillus, Penicillium, and probably Candida) [GP2010] or due to dietary sources containing glycerol (glycerin).
  • Elevated titers may also indicate the inborn error of metabolism genetic hyperoxaluria type II; titers of glyceric acid within the reference range rule out genetic causes of oxaluria Go to MosaicDXMosaicDX.

Glycolic Acid

  • Elevated glycolic acid titers without elevated oxalic acid are most likely a result of GI yeast overgrowth (Aspergillus, Penicillium, probably Candida) [GP2010] or dietary sources containing glycerol (glycerin).
  • Associated with autism, vulvar pain, fibromyalgia [GP2010].
  • Elevated titers may also indicate the inborn error of metabolism genetic hyperoxaluria type I; titers of glyceric acid within the reference range rule out genetic causes of oxaluria Go to MosaicDXMosaicDX.

Oxalic Acid (Oxalate)

  • Elevated titers of oxalic acid may be due to many causes, including:
    • Primary hyperoxaluria (genetic)
    • Diabetes mellitus,
    • Cirrhosis,
    • Vitamin B6 deficiency,
    • Sarcoidosis,
    • Steatorrhea due to pancreatic insufficiency,
    • Celiac disease,
    • Bacteria overgrowth,
    • Aspergillus, Penicillium, and probably Candida overgrowth [GP2010], [Mosaic2024],
    • Ileal resection,
    • Biliary tract disease,
    • Small bowel disease,
    • Ethylene glycol (anti-freeze) poisoning [Mosaic2024], Go to MosaicDXMosaicDX,
    • Environmental pollutants such as trichloroacetic acid [Mosaic2024],
    • Overconsumption of foods high in oxalate, including rhubarb, spinach, raspberries, beets, chocolate, wheat bran, tea, cashews, pecans, almonds, and peanuts [Great Plains Laboratories - link no longer available], [Mosaic2024],
    • High doses of vitamin C [Mosaic2024], or decomposition of vitamin C during storage [Mosaic2024], Go to MosaicDXMosaicDX,
    • Consider treating with taurine (1000mg/day) to increase bile production [Mosaic2024],
    • Poor fat absorption, perhaps due to excessive fat intake or inadequate bile flow, increases calcium binding to fatty acids in the gut and concomitant reduction in calcium binding to oxalate [GP2010]. Consider treating with taurine (1000mg/day) to increase bile production or consuming calcium citrate before fatty meals[Mosaic2024],
  • If glycolic acid is also elevated, it suggests the genetic disease hyperoxaluria type I [Mosaic2024]
  • If glyceric acid is also elevated, it suggests the genetic disease hyperoxaluria type II [Mosaic2024].
  • The genetic disease hyperoxaluria type III is also a possibility [Mosaic2024].
  • Elevated oxalic acid titers have been associated with:
  • Antifungal therapy may reduce oxalates if yeast or fungal markers are elevated Go to MosaicDXMosaicDX.
  • For more information see [Mosaic2024]

Glycolysis Intermediates

Lactic Acid (Lactate)

  • Elevated lactic acid titers may indicate infection, recent vigorous exercise, B vitamin deficiency, shock, poor perfusion, intestinal bacterial overgrowth, or mitochondrial dysfunction Go to MosaicDXMosaicDX.
  • Elevated titers of lactic acid may be associated with mitochondrial electron transport chain dysfunction in Complex I [Garaude2016  🕮 ].
  • Extremely elevated titers (over 300 mmol/mol creatinine) suggest severe trauma, life-threatening infections, or genetic diseases such as pyruvate dehydrogenase deficiency, glycogen storage diseases, or disorders of fructose metabolism Go to MosaicDXMosaicDX, .

Pyruvic Acid (Pyruvate)

  • Pyruvic acid is the end-product of glycolysis in the cell cytosol. It enters the mitochondria and is further broken down by the enzyme pyruvate dehydrogenase to form acetyl-CoA, NADH, and CO2. The acetyl-CoA then enters the Krebs cycle and the NADH eventually enters the electron transport chain (see below) [Nelson2000, pg 568].
  • Pyruvate dehydrogenase is a complex enzyme system that is tightly regulated by allosteric factors and covalent modification and depends on five different cofactors, including:
    • TPP (thiamine pyrophosphate from vitamin B1),
    • FAD (flavin adenine dinucleotide from Vitamin B2),
    • NAD+ (nicotinamide adenine dinucleotide from vitamin B3),
    • CoA-SH (coenzyme-A from vitamin B5),
    • Lipoate (from alpha-lipoic acid) [Nelson2000, pp 568-570].
  • Elevated pyruvic acid titers may be a normal physiological response to recent vigorous exercise, or indicate poor perfusion, anemia, shock, B vitamin deficiency (especially thiamine due to diet of unfortified white rice or distilled spirits) [Nelson2000, pg 571], infection, intestinal bacterial overgrowth, or mitochondrial dysfunction [Mills2018  🕮 ] Go to MosaicDXMosaicDX.
  • Extremely elevated titers of pyruvic acid (over 100 mmol/mol creatinine) indicate severe trauma, life-threatening infections, genetic diseases such as pyruvate dehydrogenase deficiency, glycogen storage diseases, or disorders of fructose metabolism Go to MosaicDXMosaicDX.

2-Hydroxybutyric Acid

  • 2-Hydroxybutyric acid is a metabolite of cystathionine Go to MosaicDXMosaicDX.
  • Moderately elevated titers may indicate infection, recent vigorous exercise, poor perfusion, oxidative stress, toxic exposures, or deficiencies of methyl tetrahydrofolate, methyl B12, or betaine Go to MosaicDXMosaicDX.
  • Considerably elevated titers may indicate severe trauma, life-threatening infections, or genetic diseases such as pyruvate dehydrogenase deficiency, glycogen storage disease, disorders of fructose metabolism, or the methylation pathway.

Krebs Cycle Intermediates

The Krebs cycle is also called the citric acid cycle or the tricarboxylic acid cycle. It is a series of 10 enzymatic reactions that occur within the mitochondria in the body and is key to proper energy metabolism [Nelson2000, pg 572], Go to WikipediaWikipedia.

The Krebs cycle is tightly coupled with the mitochondrial electron transport chain (ETC). In fact, Complex II of the ETC, succinate dehydrogenase, is also part of the Krebs cycle <&Zhao2019&>.

Dr. Weyrich notes that this section requires further elaboration and additional citations.

Citric Acid (Citrate)

  • Citric acid is produced by the Krebs cycle enzyme citrate synthase acting on the precursors acetyl-CoA and oxaloacetic acid [Nelson2000, pg 572], Go to WikipediaWikipedia. Citrate synthase requires no cofactors.
  • Altered titers of citric acid may be associated with mitochondrial electron transport chain dysfunction in Complex I [He2004  🕮 ].
  • When citric, 2-Oxoglutaric, fumaric, and malic acid titers are all elevated, a mitochondrial energy pathway dysfunction is likely Go to MosaicDXMosaicDX.
  • Do not confuse citric acid with ascorbic acid (vitamin C). They are both found in citrus fruit but are not the same compound.
  • Elevated citric acid may be due to dietary intake, intestinal yeast producing citric acid, intestinal yeast metabolites inhibiting the human Krebs Cycle, the depletion of glutathione, which is a required cofactor for the enzyme aconitase that metabolizes cis-aconitic and citric acids) [GP2010] Go to MosaicDXMosaicDX.
  • Consider supplementing glutathione or n-acetyl-cysteine if pyroglutamic acid titers are low Go to MosaicDXMosaicDX.

cis-Aconitic Acid

  • cis-Aconitic acid is produced by the Krebs cycle enzyme aconitase acting on the precursor citric acid [Nelson2000, pg 572], Go to WikipediaWikipedia. Aconitase requires an iron-sulfur cluster at its active center .
  • Its titer may be elevated due to a deficiency in glutathione since the enzyme aconitase requires reduced glutathione [need cite] to metabolize cis-aconitic to citric acid or mitochondrial dysfunction (e.g., Complex I and Pierson Syndrome) Go to MosaicDXMosaicDX.

D-Isocitric Acid (D-Isocitrate)

  • D-isocitric acid is produced by the Krebs cycle enzyme aconitase acting on the precursor cis-aconitic acid [Nelson2000, pg 572], Go to WikipediaWikipedia.

2-Oxoglutaric Acid (alpha-Ketoglutaric Acid, alpha-Ketoglutarate, AKG)

  • AKG is produced by the Krebs cycle enzyme isocitrate dehydrogenase acting on the precursor D-Isocitric acid. This process requires the cofactor NAD+ (derived from vitamin B3) [Nelson2000, pg 572], Go to WikipediaWikipedia. Other sources suggest that magnesium, manganese, zinc, or calcium are additional required cofactors [need cite].
  • Isocitrate dehydrogenase is the rate-determining step in converting D-isocitric acid to alpha-ketoglutaric acid.
  • Isocitrate dehydrogenase is allosterically activated by citric acid (an indirect precursor) and ADP (an indicator of low cellular energy) [need cite].
  • Isocitrate dehydrogenase is allosterically inhibited by ATP and NADH (indicators of adequate cellular energy) [need cite]. However, Dr. Weyrich notes that NADH may also be elevated if there is a blockage in Complex I of the electron transport chain [He2004  🕮 ].
  • Dr. Weyrich notes that blockage of isocitrate dehydrogenase due to the above factors can lead to elevations in citric acid levels, reduction in AKG, and an increased ratio of citric acid to AKG.
  • When citric, 2-Oxoglutaric, fumaric, and malic acid titers are all elevated, a mitochondrial energy pathway dysfunction is likely Go to MosaicDXMosaicDX.
  • Alternatively, 2-oxoglutaric acid may be derived from converting glutamic acid to 2-oxoglutaric by deamination or transamination.
  • Elevated urine titers of AKG may be due to vitamin deficiencies (vitamins B1, B2, B5) blocking the conversion of 2-oxoglutaric acid to succinyl-CoA or dietary intake of 2-ketoglutaric acid Go to MosaicDXMosaicDX.
  • Very low titers are associated with chronic fatigue syndrome.
  • Anecdotal reports indicate that autistic symptoms sometimes improve with AKG supplementation in response to low titers of this metabolite.

Succinal-Co-A

  • Succinal-Co-A is produced by the Krebs cycle enzyme alpha-ketoglutarate dehydrogenase acting on the precursor AKG. This process requires the cofactors NAD+ (derived from vitamin B3) and CoA-SH (derived from vitamin B5) [Nelson2000, pg 572], Go to WikipediaWikipedia.

Succinic Acid (Succinate)

  • Succinic acid is produced by the Krebs cycle enzyme succinyl-CoA synthase acting on the precursor succinyl-CoA. This process requires the cofactors GDP (interchangeable with ADP) and inorganic phosphorus [Nelson2000, pg 572], Go to WikipediaWikipedia.
  • Elevated titers of succinic acid are associated with mitochondrial electron transport chain dysfunction in Complex I, which then impairs the function of Complex II (succinic dehydrogenase) [Chouchani2014  🕮 ], [Garaude2016  🕮 ], [He2004  🕮 ]. This impaired Complex II function, in turn, alters cellular metabolism and signaling [Reyes2020  🕮 ].
  • Succinic acid titers may be elevated due to environmental toxicity, riboflavin deficiency, coenzyme Q-10 deficiency, bacterial conversion of dietary glutamine to succinic acid in the gastrointestinal tract Go to MosaicDXMosaicDX, or inborn error of metabolism.
  • Low levels of succinic acid are associated with impairment of succinic dehydrogenase, which is further associated with failure of steroidogenesis [Bose2020]
  • Low titers of succinic acid suggest inadequate consumption of the essential branched-chain amino acids leucine and isoleucine Go to MosaicDXMosaicDX.

Fumaric Acid (Fumarate)

  • Fumaric acid is produced by the Krebs cycle enzyme succinic dehydrogenase acting on the precursor succinic acid. This process requires the cofactors Co-Q10 (ubiquinone) and FAD (derived from vitamin B2) [Nelson2000, pg 572], Go to WikipediaWikipedia.
  • Altered titers of fumaric acid are associated with mitochondrial electron transport chain dysfunction in Complex I [Reyes2020  🕮 ] or Complex II (succinic dehydrogenase) [He2004  🕮 ].
  • When citric, 2-Oxoglutaric, fumaric, and malic acid titers are all elevated, a mitochondrial energy pathway dysfunction is likely Go to MosaicDXMosaicDX.
  • Elevated titers of fumaric acid suggest impaired function of fumarase (the following enzyme in the Krebs cycle) or mitochondrial dysfunction Go to MosaicDXMosaicDX.
  • Supplements to support mitochondrial function include "coenzyme Q10, nicotinamide adenine dinucleotide (NAD+), L-carnitine and acetyl-L-carnitine, riboflavin, nicotinamide, biotin, and vitamin E" Go to MosaicDXMosaicDX.

Malic Acid (Malate)

  • Malic acid is produced by the Krebs cycle enzyme fumarase acting on the precursor fumaric acid [Nelson2000, pg 572], Go to WikipediaWikipedia.
  • When citric, 2-Oxoglutaric, fumaric, and malic acid titers are all elevated, a mitochondrial energy pathway dysfunction is likely Go to MosaicDXMosaicDX.
  • Slightly elevated titers of malic acid suggest niacin deficiency or coenzyme Q10 deficiency Go to MosaicDXMosaicDX.

Oxaloacetic Acid (Oxaloacetate)

  • Oxaloacetic acid is produced by the Krebs cycle enzyme malate dehydrogenase acting on the precursor malic acid. This process requires the cofactor NAD+ (derived from vitamin B3) [Nelson2000, pg 572], Go to WikipediaWikipedia.
  • Oxaloacetic acid can be elevated due to oxidative stress or mitochondrial dysfunction [need cite].
  • Alternatively, oxaloacetic acid can be produced by the enzyme pyruvate carboxylase acting on the precursor pyruvic acid (pyruvate). This process requires the cofactor bicarbonate (HCO+3 (derived from CO2 Go to WikipediaWikipedia.

Amino Acid Metabolites (Mitochondria)

3-Methylglutaric Acid and 3-Methylglutaconic Acid

  • Elevated titers of the metabolites 3-methylglutaric acid or 3-methylglutaconic acid suggest a reduced ability to metabolize leucine due to the genetic diseases 3-hydroxy-3-methylglutaric aciduria or 3-methylglutaconic aciduria Go to MosaicDXMosaicDX.
  • Supplements to support mitochondrial function include "coenzyme Q10, niacin, L-carnitine and acetyl-L-carnitine, riboflavin, nicotinamide, biotin, and vitamin E" Go to MosaicDXMosaicDX.

3-Hydroxyglutaric Acid

  • A slight elevation in 3-Hydroxyglutaric Acid titer suggests mitochondrial dysfunction Go to MosaicDXMosaicDX.
  • Greater elevations suggest a deficiency in glutaryl CoA dehydrogenase, which metabolizes tryptophan, lysine, and hydroxylysine. This defect is associated with the genetic disease glutaric aciduria type 1 Go to MosaicDXMosaicDX.
  • Elevated 3-hydroxyglutaric acid may occur concomitantly with glutaric and glutaconic acids Go to MosaicDXMosaicDX.
  • Symptoms vary but include "encephalopathy, autism, cerebral palsy, and additional neurological abnormalities" Go to MosaicDXMosaicDX.
  • Treatment is a diet low in lysine and supplementation with carnitine Go to MosaicDXMosaicDX.

Amino Acid Metabolites

2-Hydroxyisovaleric Acid

  • Slight elevations in 2-hydroxyisovaleric acid may be due to thiamine or lipoic acid deficiencies, lactic acidosis, or episodic ketosis Go to MosaicDXMosaicDX.
  • Elevated titers are also associated with genetic disorders such as maple syrup urine disease and pyruvate dehydrogenase deficiency Go to MosaicDXMosaicDX.

2-Oxoisovaleric Acid

  • Slight elevations in 2-oxoisovaleric acid may be due to thiamine or lipoic acid deficiencies, lactic acidosis, or episodic ketosis Go to MosaicDXMosaicDX.
  • Elevated titers are also associated with the genetic disorders maple syrup urine disease and pyruvate dehydrogenase deficiency Go to MosaicDXMosaicDX.

3-Methyl-2-oxovaleric Acid

  • Slight elevations in 3-methyl-2-oxovaleric acid may be due to thiamine or lipoic acid deficiencies.
  • Elevated titers are also associated with the genetic diseases maple syrup urine disease and pyruvate dehydrogenase deficiency Go to MosaicDXMosaicDX.

2-Hydroxyisocaproic Acid

  • Slight elevations in 2-hydroxyisocaproic acid may be due to thiamine or lipoic acid deficiencies, lactic acidosis, or episodic ketosis Go to MosaicDXMosaicDX.
  • Elevated titers are also associated with short bowel syndrome or the genetic diseases maple syrup urine disease and pyruvate dehydrogenase deficiency Go to MosaicDXMosaicDX.

2-Oxoisocaproic Acid

  • Slight elevations in 2-oxoisocaproic acid may be due to thiamine or lipoic acid deficiencies, lactic acidosis, or episodic ketosis Go to MosaicDXMosaicDX.
  • Elevated titers are also associated with the genetic diseases maple syrup urine disease and pyruvate dehydrogenase deficiency Go to MosaicDXMosaicDX.

2-Oxo-4-methylbutyric Acid

  • 2-Oxo-4-methylbutyric acid is elevated in methioninemia, a genetic disease of methionine metabolism, which is associated with myopathy and mental deficiency [Gaull1981  🕮 ].

Mandelic Acid

  • Mandelic acid is elevated in the genetic diseases phenylketonuria (PKU) and tyrosinemia.
  • Slight elevations may result from increased dietary intake of phenylalanine or exposure to styrene Go to MosaicDXMosaicDX.

Phenylacetic Acid

  • Phenylacetic acid is elevated in the genetic diseases phenylketonuria (PKU) and tyrosinemia.
  • Slight elevations may result from increased dietary intake of phenylalanine.

Phenylpyruvic Acid

  • Phenylpyruvic acid is elevated in the genetic diseases phenylketonuria (PKU) and tyrosinemia.
  • Slight elevations may result from increased dietary intake of phenylalanine or a deficiency in biopterin production, a cofactor required for phenylalanine metabolism Go to MosaicDXMosaicDX.

Homogentisic Acid

  • Homogentisic acid is elevated in the genetic disease homogentisic aciduria (alkaptonuria).

4-Hydroxyphenyllactic Acid

  • 4-Hydroxyphenyllactic acid is significantly elevated in the genetic diseases tyrosinemia and phenylketonuria.
  • A slight increase may be due to increased tyrosine intake, "bacterial gut metabolism, short bowel syndrome, or liver disease" Go to MosaicDXMosaicDX.
  • Associated with post-COVID-19 syndrome [Sobolev2023  🕮 ].

N-acetylaspartic Acid

  • High titers of N-acetylaspartic acid suggest Carnavan's disease, a potentially fatal genetic disease that causes a spongy degeneration of the brain Go to MosaicDXMosaicDX.

Malonic Acid

  • Elevated titers of malonic acid may be associated with the genetic disease malonyl-CoA decarboxylase deficiency Go to MosaicDXMosaicDX.
  • Mild elevations are unlikely to be clinically significant Go to MosaicDXMosaicDX.

3-Indoleacetic Acid

  • 3-Indoleacetic acid is a metabolite of the amino acid tryptophan.
  • Elevated titers are associated with Hartnup disease, a genetic neurological disease due to defective renal and intestinal transport of certain neutral amino acids.
  • Elevations of lesser magnitude appear to be associated with Clostridium stricklandii, Clostridium lituseburense, Clostridium subterminale, and Clostridium putrefaciens in the small intestine [Mosaic2024].

Neurotransmitter Metabolites

Homovanillic Acid (HVA, Homovanillate)

  • HVA is a metabolite of the catecholamine neurotransmitter dopamine; therefore, it can serve as a surrogate marker of dopamine titers in circulation [GP2010].
  • HVA may be elevated due to:
    • Stress or sympathetic nervous stimulation (elevated adrenal output)[PA-OAT]
    • Lead toxicity Go to MosaicDXMosaicDX.
    • Deficiency of Cu or Vitamin C [PA-OAT]
    • Administration of catecholamine precursors such as L-dopa, tyrosine, or phenylalanine [PA-OAT]
    • Neuroblastoma, ganglioneuroblastoma, or pheochromocytoma tumors (consider 24-hour VMA and HVA test if OAT results exceed twice the reference range) [GP2010]
    • MAO inhibitors [PA-OAT]
    • Dopaminergic medications (L-dopa, Levodopa, Sinemet, Methyldopa) [PA-OAT]
    • Dopamine-containing foods/supplements (Mucuna pruriens, bananas) [PA-OAT]
    • SNRI (Wellbutrin) [PA-OAT]
    • Tricyclic antidepressants [PA-OAT]
    • Amphetamines [PA-OAT]
    • Appetite suppressants [PA-OAT]
    • Caffeine [PA-OAT]
    • Quercetin [PA-OAT]
  • Low titers of HVA can be due to:
    • Low titers of dopamine secondary to deficiencies of tetrahydrobiopterin (BH4), Fe, or tyrosine [PA-OAT]
    • Low adrenal function [PA-OAT]
    • Poor conversion of dopamine to HVA secondary to deficiencies of SAM, Mg, FADH2, or NADH [PA-OAT]
  • If HVA titers are significantly higher than VMA titers, the patient may be having trouble converting dopamine to norepinephrine due to a copper or vitamin C deficiency or trouble converting norepinephrine to VMA due to low COMT (Catecholamine O-Methyl Transferase) or MAO (Monoamine Oxidase) enzyme activity [PA-OAT]
  • Signs of low dopamine titers include:
  • Signs of elevated dopamine titers include:

Vanillylmandelic Acid (VMA, Vanillylmandelate)

  • VMA is a metabolite of catecholamine neurotransmitters norepinephrine and epinephrine; it is a surrogate marker of norepinephrine/epinephrine titers in circulation [GP2010].
  • VMA may be elevated due to:
    • Physical or psychological stress or sympathetic nervous stimulation (elevated adrenal output) [PA-OAT]),
    • Lead toxicity Go to MosaicDXMosaicDX,
    • Administration of catecholamine precursors such as dopamine, L-dopa, tyrosine, or phenylalanine Go to MosaicDXMosaicDX,
    • Drugs (see HVA),
    • Neuroblastoma, ganglioneuroblastoma, and pheochromocytoma tumors (consider 24-hour VMA and HVA test if OAT results exceed twice the upper bound of the reference range) [GP2010],
    • Clostridia metabolites Go to MosaicDXMosaicDX.
  • Low titers of VMA can be due to:
    • Low titers of dopamine precursor.
    • Trouble converting norepinephrine to VMA secondary to low COMT (catechol-O-methyltransferase) enzyme activity [PA-OAT].
    • Trouble converting norepinephrine to VMA secondary to low MAO (monoamine oxidase) enzyme activity, including MAO-inhibitor (MAO) drugs [PA-OAT]
  • Signs of low norepinephrine/epinephrine titers include:
  • Signs of elevated norepinephrine/epinephrine titers include:

HVA/VMA Ratio

  • An elevated ratio of HVA to VMA suggests decreased conversion of dopamine to norepinephrine by dopamine beta-hydroxylase, which is often due to Clostridia metabolites such as HPHPA, 4-hydroxyphenylacetic acid, or 4-cresol Go to MosaicDXMosaicDX.

Dihydroxyphenylacetic Acid (DOPAC)

  • DOPAC is a metabolite of dopamine.
  • DOPAC titers may be elevated due to the following: Go to MosaicDXMosaicDX:
    • Inhibition of dopamine beta-hydroxylase (DBH) by Clostridia metabolites,
    • Inhibition of DBH by the mold metabolite fusaric acid,
    • Pharmaceuticals such as disulfiram,
    • Food additives such as aspartame,
    • Deficiency of cofactors copper, vitamin C, or malic acid.
  • DOPAC titers may be low due to the following: Go to MosaicDXMosaicDX:
    • Decreased intake or absorption of dopamine's precursor amino acids phenylalanine and tyrosine,
    • Deficiency cofactors needed for the biosynthesis of dopamine, such as tetrahydrobiopterin or vitamin B6,
    • Pharmaceuticals such as monoamine oxidase (MAO) inhibitors,
    • Genetic polymorphisms (SNPs) of MAO or aldehyde dehydrogenase.

HVA/DOPAC Ratio

  • The ratio of HVA to DOPAC can be increased by the increased availability of S-adenosyl methionine (SAMe) due to SAMe supplementation or factors of SAMe production, such as methyltetrahydrofolate or methylcobalamin Go to MosaicDXMosaicDX.
  • The HVA/DOPAC ratio can be reduced by decreased conversion of DOPAC to HVA due to a genetic deficiency of catechol-O-methyltransferase (COMT) or a nutritional deficiency of SAMe Go to MosaicDXMosaicDX.

5-Hydroxyindoleacetic Acid (5-hydroxyindoleacetate, 5-HIAA)

  • 5-HIAA is a serotonin metabolite and surrogate marker of serotonin titers in circulation [GP2010], Go to MosaicDXMosaicDX.
  • 5-HIAA may be elevated due to:
    • Ingestion of tryptophan or 5-hydroxytryptophan (5-HTP) supplements,
    • Increased turnover of serotonin secondary to SSRI use,
    • Carcinoid syndrome [GP2010],
    • Bronchial adenoma of carcinoid type [GP2010],
    • Carcinoid tumor (very high titer) [PA-OAT],
    • Celiac sprue [GP2010],
    • Tropical sprue [GP2010],
    • Whipple's disease [GP2010],
    • Oat cell carcinoma of the bronchus [GP2010],
    • Intake of foods high in hydroxyindoles such as walnuts, avocado, eggplant, plums, tomatoes [GP2010], butternuts, black walnuts, plantain, pecans, [PA-OAT], pineapple, bananas [PA-OAT], [GP2010].
  • Low titers of 5-HIAA can be due to:
    • Decreased intake of tryptophan or 5-HTP,
    • Depressive illnesses [GP2010],
    • Small intestine resection [GP2010],
    • Mastocytosis [GP2010],
    • PKU [GP2010],
    • Hartnup disease [GP2010],
    • Decreased availability of tryptophan (caused by elevated estrogen [?], cortisol, or inflammation. These push tryptophan down the kynurenine pathway rather than the serotonin pathway) [PA-OAT],
    • Low titers of estrogen [?] because the estrogen receptor beta (ER-beta) induces tryptophan hydroxylase, which is the rate-limiting step for making 5-HTP (a precursor of serotonin).
  • Only 1% of the serotonin in circulation is made in the brain; 80% is made in the gut [PA-OAT].
  • Serotonin promotes gut motility and activates smooth muscle [PA-OAT].
  • Serotonin is found in several areas of the brain, including:
    • Dorsal raphe nucleus (DRN) in the brain stem, which is also rich in estrogen receptors [PA-OAT]
    • Forebrain (cerebrum, thalamus, hypothalamus, pituitary, limbic) [PA-OAT]

Quinolinic Acid

  • Elevated titers of quinolinic acid suggest chronic inflammation due to microbial infections, central nervous system degeneration, excessive tryptophan supplementation, or exposure to phthalates Go to MosaicDXMosaicDX.
  • This chronic inflammation can induce brain damage but may be mitigated by supplementing with acetyl L-carnitine, melatonin, vitamin B6, turmeric, or garlic Go to MosaicDXMosaicDX.

Kynurenic Acid (KYNA)

  • The reaction by which kynurenine is converted to hydroxyanthranilate is catalyzed by an enzyme requiring vitamin B6. Thus, elevations of kynurenic acid may indicate a vitamin B6 deficiency.
  • Other causes of high titers are yeast overgrowth syndrome, other chronic infections, or genetic disorders affecting kynureninase Go to MosaicDXMosaicDX.

6-Hydroxymelatonin Sulfate (6-OHMS)

  • 6-OHMS is a metabolite of melatonin that can act as a surrogate marker of melatonin titers in circulation [PA-OAT].

Pyrimidines

Uracil

  • Folic acid acts as a methyl donor in converting uracil to thymine, so elevated uracil titers suggest a problem in folic acid metabolism Go to MosaicDXMosaicDX.
  • About 10% of children with autism have elevated uracil Go to MosaicDXMosaicDX.
  • Uracil and thymine are pyrimidines that are elevated in the mitochondrial genetic disease dihydropyrimidine dehydrogenase deficiency.
  • Uracil and orotic acid are also elevated in the genetic diseases of ornithine transcarbamylase (OTC) deficiency and citrullinemia.

Thymine

  • Uracil and thymine are pyrimidines that are elevated in the mitochondrial genetic disease dihydropyrimidine dehydrogenase deficiency.
  • High titers of thymine are also associated with inflammatory diseases, cancer, seizures, and autism Go to MosaicDXMosaicDX.

Phosphoric Acid

  • Excess urinary phosphate excretion may correlate with dietary intake of processed foods such as sodas, commercially baked goods, and meats Go to MosaicDXMosaicDX.
  • Excess urinary phosphate excretion may also suggest metabolic problems such as hyperparathyroidism, vitamin D-resistant rickets, bone resorption, vitamin D overdose, renal tubular damage, familial hypophosphatemia, or metabolic acidosis Go to MosaicDXMosaicDX.
  • Low urinary phosphate is most common in low phosphate intake and vitamin D deficiency" Go to MosaicDXMosaicDX.

Fatty Acid Metabolites

3-Hydroxybutyric Acid

  • 3-Hydroxybutyric acid is associated with excessive fatty acid oxidation.
  • It may be elevated due to fasting or starvation, protein malnutrition, diabetes mellitus, high-fat (ketogenic) diet use, vitamin B12 deficiency, severe GI Candida overgrowth, pulmonary infections, and several genetic diseases [GP2010], Go to MosaicDXMosaicDX.

Acetoacetic Acid

  • Acetoacetic acid is associated with excessive fatty acid oxidation.
  • It may be elevated due to fasting or starvation, protein malnutrition, diabetes mellitus, high-fat (ketogenic) diets, vitamin B12 deficiency, severe GI Candida overgrowth, pulmonary infections, nausea, influenza, or genetic diseases [GP2010], Go to MosaicDXMosaicDX.

4-Hydroxybutyric Acid

  • Elevated titers of 4-hydroxybutyric acid may indicate the genetic diseases 3-methylglutaconic aciduria or succinic semialdehyde dehydrogenase Go to MosaicDXMosaicDX.
  • Elevated titers may also indicate excessive intake of the muscle builder 4-hydroxybutyric acid (also called gamma-hydroxybutyric acid), which can cause severe myalgia or death.

Adipic Acid (Adipate)

  • Adipic acid is a fatty acid metabolite (6-carbon dicarboxylic acid).
  • It is a product of peroxisomal fatty acid oxidation [MetaMetrix2010].
  • Its titer may be elevated in the following:
    • Fasting [GP2010], ketosis [GP2010] or metabolic acidosis [MetaMetrix2010],
    • Excessive intake of adipic acid-containing foods such as Jell-O, particularly if suberic acid is not elevated [GP2010]; [MetaMetrix2010],
    • Increased intake of foods containing medium chain triglycerides such as coconut oil [GP2010],
    • Functional deficiency of the fat-transporting molecule carnitine may prevent the entry of long-chain fatty acids into mitochondria, leading to incomplete fatty acid oxidation [GP2010]. For carnitine deficiency, consider supplementation with L-carnitine (CI with certain thyroid medications) (500 to 1000mg) TID or L-lysine (precursor to carnitine) (1000mg QD to TID); also consider SAMe, vitamin B6, Mg, vitamin C, iron, niacin, and adequate protein intake [MetaMetrix2010].
    • Mitochondrial dysfunction. Consider vitamin B2 (100mg BID) [MetaMetrix2010].
    • Genetic deficiencies of fatty acid metabolism [GP2010],
    • Genetic disease multiple acyl dehydrogenase deficiency [GP2010],
    • Environmental toxins [MetaMetrix2010],
    • Periodic mild weakness [MetaMetrix2010],
    • Nausea [MetaMetrix2010],
    • Fatigue [MetaMetrix2010].
    • Hypoglycemia [MetaMetrix2010],
    • Recurrent infections [MetaMetrix2010],
    • Sweaty foot odor [MetaMetrix2010],
    • Reye syndrome (fatty acid oxidation inhibition) is associated with aspirin, viral infections, or genetic mutations [MetaMetrix2010],
    • Elevated titers of adipic acid but not suberic acid are associated with patients having ADD, lethargy, or seizures [GP2010].

For carnitine deficiency, consider supplementation with L-carnitine (CI with certain thyroid medications) (500 to 1000mg) TID or L-lysine (precursor to carnitine) (1000mg QD to TID); also consider SAMe, vitamin B6, Mg, vitamin C, iron, niacin, and adequate protein intake [MetaMetrix2010].

Suberic Acid (Suberate)

Sebacic Acid

  • Sebacic acid is a fatty acid metabolite.
  • Its titer may be elevated in ketosis, fasting, deficiency of the fat-transporting molecule carnitine, genetic deficiencies of fatty acid metabolism and the genetic disease multiple acyl dehydrogenase deficiency, consumption of adipic acid-containing foods, such as Jell-O, consumption of foods containing medium-chain triglycerides, such as coconut oil and some infant formulas Go to MosaicDXMosaicDX.
  • Defects in sebacic acid metabolism are associated with hypoglycemia and lethargy Go to MosaicDXMosaicDX.

Ethylmalonic Acid

  • Ethylmalonic acid is a five-carbon branched chain dicarboxylic acid formed in isoleucine metabolism [MetaMetrix2010] and fatty acid metabolism.
  • Titers may be elevated:
    • In ketosis,
    • Fasting, functional deficiency of the fat-transporting molecule carnitine,
    • Genetic deficiencies of fatty acid metabolism, such as multiple acyl dehydrogenase deficiency,
    • Consumption of adipic acid-containing foods, such as Jell-O, consumption of foods containing medium-chain triglycerides, such as coconut oil and some infant formulas Go to MosaicDXMosaicDX,
    • Impairment of short-chain fatty acid oxidation, leading to the elevation of butyrate, which may be converted to ethylmalonic acid [MetaMetrix2010],
    • Riboflavin deficiency [MetaMetrix2010],
    • Inability to form or oxidize butyrylcarnitine [MetaMetrix2010].
  • Defects in ethylmalonic acid metabolism are associated with hypoglycemia and lethargy Go to MosaicDXMosaicDX.
  • See adipic acid (above) for treatment [MetaMetrix2010].

Methylsuccinic Acid

  • Methylsuccinic acid is a fatty acid metabolite.
  • Its titer may be elevated in ketosis, fasting, deficiency of the fat-transporting molecule carnitine, genetic deficiencies of fatty acid metabolism, the genetic disease multiple acyl dehydrogenase deficiency, consumption of adipic acid-containing foods, such as Jell-O, consumption of foods containing medium-chain triglycerides, such as coconut oil, and some infant formulas Go to MosaicDXMosaicDX,
  • Defects in methylsuccinic acid metabolism are associated with hypoglycemia and lethargy Go to MosaicDXMosaicDX.

Vitamin Indicators and Metabolites

Methylmalonic Acid (Ethylmalonate) (Vitamin B12)

  • Moderate increases in methylmalonic acid may be due to vitamin B12 deficiency, pernicious anemia, GI bacterial metabolism, malabsorption, or gastroenteritis Go to MosaicDXMosaicDX,
  • Greatly elevated titers may also be due to the genetic disorder methylmalonic aciduria [GP2010].

Pyridoxic Acid (Vitamin B6)

  • Pyridoxic acid is the primary urinary metabolite of pyridoxine (vitamin B6) and measures recent dietary intake.
  • Low titers of pyridoxic acid in the urine indicate low recent intake, while high titers indicate high recent dietary intake.
  • High titers are not necessarily undesirable.
  • Vitamin B6 deficiency is associated with high oxalate titers and low neurotransmitter titers Go to MosaicDXMosaicDX.

Xanthurenic Acid (Xanthurenate) (Vitamin B6)

  • Xanthurenic acid is a tryptophan metabolite that may be elevated with vitamin B6 deficiency (conversion of tryptophan to NAD requires B6; in the absence of B6, xanthurenic acid is produced instead [PA-OAT].
  • Elevated titers are a functional marker of intracellular vitamin B6 deficiency, inflammation, excess estrogen, or excess cortisol [PA-OAT].
  • Complexes with insulin and decreases insulin sensitivity [PA-OAT].
  • Complexes with iron and causes oxidative damage to DNA (increases 8-hydroxydeoxyguanosine (8-OHdG) marker for oxidative damage) [PA-OAT].

Pantothenic Acid (Vitamin B5)

  • Urinary excretion reflects dietary intake.
  • High titers are not necessarily undesirable.
  • Individuals may have a much higher than usual requirement for pantothenic acid.

Glutaric Acid (Vitamin B2)

  • Glutaric acid is elevated in the genetic diseases glutaric acidemia types I and II.
  • Moderate increases may be due to riboflavin deficiency, coenzyme Q-10 deficiency, fatty acid oxidation defects, valproic acid (Depakene), or celiac disease Go to MosaicDXMosaicDX.
  • Moderate increases are associated with about 10% of children with autism Go to MosaicDXMosaicDX, possibly due to defective vitamin absorption or microbial production in the GI tract.
  • Very high titers suggest an inborn error of metabolism Go to MosaicDXMosaicDX,

Ascorbic Acid (Vitamin C)

  • Ascorbic acid is an important antioxidant.
  • Low titers may indicate dietary deficiency (scurvy).
  • Low titers are associated with chronic fatigue syndrome.
  • High titers are usually due to dietary intake.
  • Extremely high intake (over 2000 mg/day) raises concern that in individuals with bacteria overgrowth of the GI tract, ascorbic acid may be converted to oxalic acid, which can lead to kidney stones. There is a low probability that elevated vitamin C will cause kidney stones if oxalic acid is in the normal range Go to MosaicDXMosaicDX.

3-Hydroxy-3-methylglutaric Acid (HMG) (Coenzyme Q10)

  • HMG is the precursor of mevalonic acid, Co-Q10, and cholesterol. Statin drugs inhibit the conversion of HMG to mevalonic acid by HMG-CoA reductase and thus cause increased titers of HMG and decreased titers of Co-Q10.
  • Gastrointestinal yeast overgrowth may also increase HMG titers Go to MosaicDXMosaicDX.
  • Very elevated titers of HMG suggest the genetic disorder 3-hydroxy-3-methylglutaric aciduria (HMG aciduria} Go to MosaicDXMosaicDX.
  • Both yeast and humans produce these same compounds as a precursor of steroid hormones; moderate elevations in titer may be due to yeast overgrowth of the GI tract and may be associated with elevated serum cholesterol.

N-Acetylcysteine (NAC)

  • NAC is a powerful antioxidant that promotes glutathione production and is essential to detoxification in the liver.

Methylcitric Acid (Biotin or Vitamin H)

  • High titers of methylcitric acid suggest biotin deficiency or an inborn error of metabolism affecting biotin pathways.
  • Low titers of methylcitric acid have no known significance.
  • Biotin deficiency may be due to dietary insufficiency, malabsorption, excessive intake of raw egg whites, or dysbiosis Go to MosaicDXMosaicDX.

Pyroglutamic Acid (Pyroglutamate)

  • Pyroglutamic acid is a metabolite of the antioxidant glutathione and is highly elevated in the genetic disease pyroglutamic aciduria or following the use of the antibiotics flucloxacillin or netilmicin.
  • Elevated titers are a marker of Glutathione Deficiency [PA-OAT].
  • Low titers may be found due to glutathione depletion following oxidative stress or after exposure to toxic solvents or pesticides such as chloroform, DDT, polybrominated biphenyls (PBBs), polychlorinated biphenyls (PCBs), or an overdose of acetaminophen (Tylenol) [PA-OAT].
  • Glutathione is an important antioxidant and is necessary for detoxifying estrogen metabolites 4-hydroxyestrone (4-OH-E1) and 4-hydroxyestradiol (4-OH-E2) [PA-OAT].

Toxic Indicators

Orotic Acid

  • Elevated level suggests urea cycle defect.
  • Elevated titers are most commonly associated with ammonia toxicity. When ammonia is elevated, it is biochemically converted to carbamyl phosphate and then orotic acid. Elevated ammonia may occur due to liver toxicity, viral liver infection, GI bleeding, portal-systemic shunting of blood, drug toxicity, Reye's syndrome, as well as inborn errors of ammonia metabolism Go to MosaicDXMosaicDX.
  • Elevated orotic acid may also be found in leukemias and lymphomas, possibly due to the increased production of pyrimidines.

2-Hydroxyhippuric Acid (2-hydroxybenzoylglycine)

  • 2-Hydroxyhippuric acid is a conjugate of the amino acid glycine and hydroxybenzoic acid (salicylic acid).
  • Elevated 2-Hydroxyhippuric acid is associated with the artificial sweetener aspartame (NutraSweet) Go to MosaicDXMosaicDX.

3-Hydroxyhippuric Acid (3-hydroxybenzoylglycine)

  • A conjugate of the amino acid glycine and 3-hydroxybenzoic acid (salicylic acid).
  • Elevated titers may be due to the use of aspirin (salicylates), the growth of GI bacteria producing salicylates, or after ingesting the artificial sweetener aspartame (NutraSweet) [GP2010].
  • According to [Shaw2008, pg 14], HPHPA is a metabolite derived from Clostridium spp. metabolism, which can undergo further human beta-oxidation to form 3-hydroxybenzoic acid, which is then conjugated with glycine in the liver's phase-2 detoxification step to produce 3-hydroxybenzoylglycine, also known as 3-hydroxyhippuric acid.

References regarding Organic Acid Test Panel (OAT)

  •       [Bhala1993]   Bhala A, Bennett MJ, McGowan KL, Hale DE. Limitations of 3-phenylpropionylglycine in early screening for medium-chain acyl-coenzyme A dehydrogenase deficiency. J Pediatr. 1993 Jan;122(1):100-3. PMID: 8419594PMID: 8419594
  •       [Bose2020]   Himangshu S Bose, Brendan Marshall, Dilip K Debnath, Elizabeth W Perry, Randy M Whittal. Electron Transport Chain Complex II Regulates Steroid Metabolism. iScience. 2020 Jul 24;23(7):101295. DOI: Full text: http://dx.doi.org/10.1016/j.isci.2020.101295 10.1016/j.isci.2020.101295 PCMID: Full text: PMC7334606 PMC7334606
  •       [Brown2007]   Daren W Brown, Robert A E Butchko, Mark Busman, Robert H Proctor. The Fusarium verticillioides FUM gene cluster encodes a Zn(II)2Cys6 protein that affects FUM gene expression and fumonisin production. Eukaryot Cell. 2007 Jul;6(7):1210-8. PMID: 17483290PMID: 17483290 DOI: Full text: http://dx.doi.org/10.1128/EC.00400-06 10.1128/EC.00400-06 PCMID: Full text: PMC1951116 PMC1951116
  •       [Chouchani2014]   Edward T Chouchani, Victoria R Pell, Edoardo Gaude, Dunja Aksentijević, et al. Ischaemic accumulation of succinate controls reperfusion injury through mitochondrial ROS. Nature. 2014 Nov 20;515(7527):431-435. PMID: 25383517PMID: 25383517 DOI: Full text: http://dx.doi.org/10.1038/nature13909 10.1038/nature13909 PCMID: Full text: PMC4255242 PMC4255242
    • kewbs
  •       [Elsden1976]   Elsden SR, Hilton MG, Waller JM. The end products of the metabolism of aromatic amino acids by Clostridium spp. Arch Microbiol. 1976 Apr 1;107(3):283-8. PMID: 1275638PMID: 1275638
  •       [Garaude2016]   Johan Garaude, Rebeca Acín-Pérez, Sarai Martínez-Cano, Michel Enamorado, et al. Mitochondrial respiratory-chain adaptations in macrophages contribute to antibacterial host defense. Nat Immunol. 2016 Sep;17(9):1037-1045. PMID: 27348412PMID: 27348412 DOI: Full text: http://dx.doi.org/10.1038/ni.3509 10.1038/ni.3509 PCMID: Full text: PMC4994870 PMC4994870
  •       [Gaull1981]   G E Gaull, A N Bender, D Vulovic, H H Tallan, F Schaffner. Methioninemia and myopathy: a new disorder. Ann Neurol. 1981 May;9(5):423-32. PMID: 7271238PMID: 7271238 DOI: Full text: http://dx.doi.org/10.1002/ana.410090503 10.1002/ana.410090503 Full text: https://onlinelibrary.wiley.com/doi/epdf/10.1002/ana.410090503 PAYWALL
  •       [GP2010]   Great Plains Lab Report Full text: Full text: http://www.greatplainslaboratory.com http://www.greatplainslaboratory.com
  •       [He2004]   Weihai He, Frederick J-P Miao, Daniel C-H Lin, Ralf T Schwandner, et al. Citric acid cycle intermediates as ligands for orphan G-protein-coupled receptors. Nature. 2004 May 13;429(6988):188-93. PMID: 15141213PMID: 15141213 DOI: Full text: http://dx.doi.org/10.1038/nature02488 10.1038/nature02488
  •       [Kiehn1979]   Kiehn TE, Bernard EM, Gold JW, Armstrong D. Candidiasis: detection by gas-liquid chromatography of D-arabinitol, a fungal metabolite, in human serum. Science. 1979 Nov 2;206(4418):577-80. PMID: 493963PMID: 493963
  •       [Larsson1994]   Larsson L. Determination of microbial chemical markers by gas chromatography-mass spectrometry--potential for diagnosis and studies on metabolism in situ. APMIS. 1994 Mar;102(3):161-9. PMID: 8185883PMID: 8185883
    Review article.
  •       [MetaMetrix2010]   MetaMetrix Handbook: Clinical Reference Manual, 2nd Edition. (2010). Full text: Full text: http://www.metametrix.com http://www.metametrix.com
  •       [Mills2018]   Evanna L Mills, Kerry A Pierce, Mark P Jedrychowski, Ryan Garrity, et al. Accumulation of succinate controls activation of adipose tissue thermogenesis. Nature. 2018 Aug;560(7716):102-106. PMID: 30022159PMID: 30022159 DOI: Full text: http://dx.doi.org/10.1038/s41586-018-0353-2 10.1038/s41586-018-0353-2 PCMID: Full text: PMC7045287 PMC7045287
  •       [Nelson2000]   David L Nelson and Michael M Cox. Lehninger principles of biochemistry, 3rd edition. Worth Publishers (2000).
  •       [PA-OAT]   Precision Analytical. Dried Urine Organic Acids Test Full text: Full text: https://dutchtest.com/wp-content/uploads/2017/12/OATs-Sell-Sheet.pdf https://dutchtest.com/wp-content/uploads/2017/12/OATs-Sell-Sheet.pdf Accessed: 6/30/2018..
  •       [Reyes2020]   Inmaculada Martínez-Reyes, Navdeep S Chandel. Mitochondrial TCA cycle metabolites control physiology and disease. Nat Commun. 2020 Jan 3;11(1):102. PMID: 31900386PMID: 31900386 DOI: Full text: http://dx.doi.org/10.1038/s41467-019-13668-3 10.1038/s41467-019-13668-3 PCMID: Full text: PMC6941980 PMC6941980
    • .
  •       [Robertson1968]   Robertson B, Lonnell L. Human tartrate nephropathy. Report of a fatal case. Acta Pathol Microbiol Scand. 1968;74(3):305-10. PMID: 5721197PMID: 5721197
  •       [Roboz1992]   Roboz J, Katz RN. Diagnosis of disseminated candidiasis based on serum D/L-arabinitol ratios using negative chemical ionization mass spectrometry. J Chromatogr. 1992 Mar 27;575(2):281-6. PMID: 1629305PMID: 1629305
  •       [Routledge1998]   Routledge et al. Toxicol. Appl. Pharmacol. 153, 12-19 (1998).

    Cited by [GP2010].

  •       [Shaw2005]   Shaw W, Kassen E, Chaves E. Increased urinary excretion of analogs of Krebs cycle metabolites and arabinose in two brothers with autistic features. Clin Chem. 2005 Mar;51(3):672-3. PMID: 7628083PMID: 7628083
  •       [Shaw2008]   William Shaw. Biological Treatments for Autism & PDD, Third Edition. Sunflower Pub (2008). Go to Amazon Amazon
  •       [Sobolev2023]   Pavel D Sobolev, Natalia A Burnakova, Natalia V Beloborodova, Alexander I Revelsky, Alisa K Pautova. Analysis of 4-Hydroxyphenyllactic Acid and Other Diagnostically Important Metabolites of α-Amino Acids in Human Blood Serum Using a Validated and Sensitive Ultra-High-Pressure Liquid Chromatography-Tandem Mass Spectrometry Method. Metabolites. 2023 Nov 3;13(11):1128. PMID: 37999224PMID: 37999224 DOI: Full text: http://dx.doi.org/10.3390/metabo13111128 10.3390/metabo13111128 PCMID: Full text: PMC10673366 PMC10673366
  •       [Surendran2018]   S Surendran, A Adaikalakoteswari, P Saravanan, IA Shatwaan, JA Lovegrove, and KS Vimaleswaran. An update on vitamin B12-related gene polymorphisms and B12 status. Genes Nutr. 13:2 (2018). PMID: 29445423PMID: 29445423 Full text: Full text: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5801754/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5801754/
  •       [Wong1990]    Wong B, Brauer KL, Clemens JR, Beggs S. Effects of gastrointestinal candidiasis, antibiotics, dietary arabinitol, and cortisone acetate on levels of the Candida metabolite D-arabinitol in rat serum and urine. Infect Immun. 1990 Feb;58(2):283-8. PMID: 2404865PMID: 2404865
  •       [Zhao2019]   Ru-Zhou Zhao, Shuai Jiang, Lin Zhang, Zhi-Bin Yu. Mitochondrial electron transport chain, ROS generation and uncoupling (Review). Int J Mol Med. 2019 Jul;44(1):3-15. PMID: 31115493PMID: 31115493 DOI: Full text: http://dx.doi.org/10.3892/ijmm.2019.4188 10.3892/ijmm.2019.4188 PCMID: Full text: PMC6559295 PMC6559295

    • Unless specifically noted above, references used in the construction of this web page include the following:

    [FMU] Lecture notes from Functional Medicine University.

    [SCNM] Lecture notes from Southwest College of Naturopathic Medicine.

    [UT] Lecture notes from the University of Tennessee graduate programs in Chemistry, Microbiology, and Biochemistry.