Homocysteine, a non-protein sulfur amino acid, is an intermediate product of the methionine cycle, also called the transulfuration methylation cycle that closely links sulfur amino acid metabolism with key methylation reactions. Homocysteine is formed from the catabolism of S-adenosylmethionine or by the conversion of toxic homocysteine thiolactone to homocysteine by paraoxonase 1 (PON1), the same enzyme that detoxifies organophosphate pesticides. The clearance of homocysteine requires the presence of methyltetrahydrofolate, methylcobalamin, betaine, or pyridoxal-5-phosphate. Methylcobalamin is such a powerful methylating co-enzyme that it can methylate homocysteine directly to methionine without an associated enzyme.
Click here to view a sample report.
This test requires a blood draw.