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Laboratory Test Reference Guide

Laboratory Information

Test Name


External Price (excl. GST)



Specimen Collection

Pre Testing Requirements


Specimen Collection and Transport Protocols

EDTA kept on ice until separated, and must be separated within 1 hr of collection.

Adult Specimen

EDTA (Purple) on ice. See notes.

Paediatric Specimen

0.5 ml EDTA (Purple) on ice. See notes.

Sample Delivery to Lab

Frozen plasma or whole blood on ice

Instructions for Referral to Waikato Lab

Aliquot Instructions

EDTA or Heparin blood kept on ice until separated, and must be separated within 1 hr of collection.

Aliquot Transport

Frozen plasma

Test Information



Test Availability


Laboratory Turnaround Time

7 days


cobas 6000

Unit Of Measurement


Reference Interval

5 - 15 umol/L

Uncertainty Of Measurement


Diagnostic Use Or Instructions


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.

Homocysteine and cardiovascular disease: a review of the evidence. Wierzbicki AS. Diab Vasc Dis Res. 2007 Jun;4(2):143-50

Choosing Clinical Laboratory Tests Wisely Guidelines:

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.

Additional Information

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.

We have now restricted homocysteine testing to SMO requests only.


Minimum Volume

0.2 mL EDTA Plasma (Frozen)

Electronic Information

Registration Code


HL7Mapping Code