Test Overview of Homocysteine

Homocysteine is a general marker of metabolic imbalance, and elevated levels are an independent cardiovascular risk factor.

The important point about homocysteine is that it participates in the very important S-adenosylmethionine Cycle (SAM or SAMe) that makes S-adenosylmethionine Go to Catalyst UniversityCatalyst University.

S-adenosylmethionine in turn is then consumed by many biochemical reactions that transfer a methyl group. A variety of enzymes that have "methyltransferase" in their names, such as COMT (catechol-O-methyltransferase), ASMT (acetylserotonin-N-methyltransferase), and hydroxyindole-O-methyltransferase (HIOMT) all depend on the SAM cycle.

COMT acts on neurotransmitters such as dopamine and epinephrine, and ASMT helps convert the neurotransmitter serotonin to melatonin.

In order for the SAM cycle to transfer one methyl group (called methylation), the SAM cycle requires vitamin B12, one molecule of ATP and one molecule of 5-methyltetrahydrofolate, which is derived from vitamin B9 (which is also called folic acid or folate) via the tetrahydrofolate cycle, which also consumes one molecule of ATP and two molecules of NADPH Go to Catalyst UniversityCatalyst University.

Both vitamin B12 and vitamin B9 are "essential nutrients," which means that they cannot be made by our body, but must be obtained from food. Deficiency of either of these two vitamins can cause a build-up of homocysteine.

ATP is mostly made in our mitochondria, so anything that hampers mitochondrial function can hamper the SAM cycle and the tetrahydrofolate cycle, and upset neurotransmitter balance and disrupt many other biochemical processes, including DNA maintenance.

Labs Performing Homocysteine Test

Name of LabLab CodeEstimated CostProcessing TimeComments
Go to Sonora QuestSonora Quest     

Costs cited are subject to change and may be reduced by insurance or cash discounts and increased by sample collection fees.

References regarding Homocysteine

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.