Indications:
Homocysteine is a non-essential, thiol-containing amino acid which is produced from the intracellular de-methylation of dietary methionine. It is exported from the cells into the extracellular fluid at a slow but consistent rate and circulates in the blood mainly in an oxidised form, bound to plasma proteins. There are two major pathways for its further metabolism – trans-sulphuration to cysteine (by a vitamin B6-dependent pathway) or re-methylation to methionine (by a vitamin B12 and folic acid-dependent pathway). Vitamin B2 is also required for homocysteine metabolism on account of its role in the re-cycling and maintenance of folic acid levels. Excess homocysteine accumulates in the plasma when these pathways are not operating at optimum activity.
While homocystinuria (homocysteine in the urine with elevated plasma homocysteine levels) has been known since 1962, the pathological role of moderate hyper-homocysteinemia has only been generally recognised over the past decade.
Patient Instructions:
Homocysteine is not a component of food or nutritional supplements, so the patient should not need to fast prior to the test but it’s recommended to avoid B vitamin containing supplements for 24-48 hours.
Clinical Indications:
The reference interval is 5.0-15.0 umol/L of plasma homocysteine, but the treatment goal varies (typically less than 7.0 umol/L of plasma homocysteine). An elevation of the plasma homocysteine by 5.0 umol/L has been associated with an increase of 1.7 in the odds ratio risk of cardiovascular disease. Men, on average, have a slightly higher plasma homocysteine level than women. This is thought to be associated with greater muscle mass, which increases the demand on the methyl pool for the synthesis of creatine. Age-related increases in homocysteine levels have been reported with levels increasing at a greater rate in females.
Datasheet: homocysteine.pdf
Sample Report:
Homocysteine – plasma Sample Report
Sample Requirements:
Lavender (EDTA) tube – sample should ideally be centrifuged and the plasma separated, but otherwise the whole blood sample should reach our laboratory within 8 hours of collection (store refrigerated if there’s any delay before collection).
Postal Samples:
Yes – sample must be centrifuged within 1 hour of collection, the plasma aliquoted and returned by next-day post.
Turnaround time: 1-day (15/9/26 – Currently delayed due to manufacturer’s delay in reagent issue, potentially until 25th September. Updates will be issued here when available).
Test kit instructions: Homocysteine sample preparation instructions for postal samples