Homocysteine




Test Mnemonic

HOMCYS

CPT Codes

  • 83090 - QTY (1)

LOINC ®

13965-9

Performing Laboratory

Cleveland Clinic Laboratories


Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
Volume1 mLTypePlasmaContainerLithium heparin PST (Lt. Green)Collect TemperaturePlace specimen on ice after draw.Transport TemperatureRefrigeratedSpecial InstructionsCentrifuge and separate plasma/serum from cells less than one hour after collection. If collected in a non-gel separator tube, centrifuge and transfer plasma/serum to a CCL tube and refrigerate.

Alternate Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
Volume1 mLTypeSerumContainerSST (Gold)Collect TemperaturePlace specimen on ice after draw.Transport TemperatureRefrigeratedSpecial InstructionsCentrifuge and separate plasma/serum from cells less than one hour after collection. If collected in a non-gel separator tube, centrifuge and transfer plasma/serum to a CCL tube and refrigerate.

Minimum Specimen Requirements

Volume Type Container Collect Temperature Transport Temperature Special Instructions
Volume0.5 mLType Container Collect Temperature Transport Temperature Special Instructions 

Stability

Environmental Condition Description
Environmental ConditionAmbientDescriptionAfter separation from cells: 4 days
Environmental ConditionRefrigeratedDescriptionAfter separation from cells: 4 weeks
Environmental ConditionFrozenDescriptionAfter separation from cells: 10 months

Days Performed

Sun - Sat

Turnaround Time

8 hours

Methodology

Name Description
NameEnzymaticDescription 

Reference Range

Homocysteine
Sex Age From Age To Type Range Range Unit
Homocysteine Sex18 YearsAge From99 YearsAge ToNormalType<15.1Rangeumol/L

Special Info

Homocysteine is not available for Add-On test orders.

Clinical Info

The assay can assist in the diagnosis of patients suspected of having hyperhomocysteinemia or homocystinuria. Elevated tHcy levels are caused by four major factors, including: 1. genetic deficiencies in enzymes involved in Hcy metabolism such as cystathionine beta-synthase (CBS), methionine synthase (MS), and methylenetetrahydrofolate reductase (MTHFR); 2. nutritional deficiency in B vitamins such as B6, B12 and folate; 3. renal failure for effective amino acid clearance; and 4. drug interactions, such as with nitric oxide, methotrexate and phenytoin that interfere with Hcy metabolism. Excess Hcy is related to a higher risk of coronary heart disease, stroke, and peripheral vascular disease (fatty deposits in peripheral arteries). Specimens from patients who are on drug therapy involving S-adenosylmethionine may show falsely elevated levels of homocysteine. Patients who are taking methotrexate, carbamazepine, phenytoin, nitrous oxide, anticonvulsants, or 6-azauridine triacetate may have elevated levels of homocysteine due to their effect on the pathway.