EDTA (Purple) on ice. See notes.
0.5 ml EDTA (Purple) on ice. See notes.
Frozen plasma or whole blood on ice
5 - 15 umol/L
Testing is indicated in the evaluation and follow-up of homocystinuria. In this rare genetic disease, homocysteine levels are often > 100 µmol/L. Testing may also be helpful in the evaluation of B12/Folate deficiency. MMA is more specific for B12 deficiency.
Homocysteine may also increase in patients with hepatic dysfunction, renal dysfunction, diabetes mellitus, malignancies and taking certain medications: Folate antagonists, B12 antagonists, anticonvulsants, metformin, thiazide diuretics, some glitazones, nicotinic acid and fibrates.
Patient should be fasting. Plasma must be separated within 1 hour of collection and frozen. Please notify the Laboratory that the specimen is on its way.
The DHB Shared Services
Laboratory Test Referral Guidelines note:
Plasma homocysteine may be elevated in vitamin B12 or folate deficiency, or genetic defects of B12 or folate metabolic pathways. Raised homocysteine levels are associated with increased risk of cardiovascular disease and stroke. However, homocysteine lowering interventions (e.g. folate and vitamin B6 supplementation) do not modify cardiovascular risk, despite lowering homocysteine levels. This suggests that homocysteine does not have a causative role in vascular disease so routine homocysteine testing is not recommended as part of CV risk assessment.
We have now restricted homocysteine testing to SMO requests only.