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Test Code Billings Clinic: 8516 Homocysteine, Total, Plasma

Important Note

There has been a methodology change for this assay. There is a 46% positive bias in comparison to our previous methodology.

Patients taking S-adenosyl-methionine, methotrexate, nicotinic acid, theophylline, nitrous oxide, or L-dopa can have falsely elevated Homocysteine levels.

Reference Ranges have not been established for population under age 18.

Performing Laboratory

Billings Clinic Laboratory: Chemistry

Useful For

  • Useful for biochemical diagnosis of inborn errors of methionine and related cofactors (folate, vitamin B6, and vitamin B12) metabolism.
  • This test is also useful as an independent risk factor of cardiovascular disease, an indicator of acquired folate or cobalamin deficiency, and as a contributing factor in the pathogenesis of neural tube defects.

Methodology

Chemiluminescent Immunoassay

 

Specimen Requirements

Plasma

  • Draw blood in a green-top (lithium heparin) tube(s). 
  • Spin down immediately and send 1 mL of heparinized plasma frozen in plastic vial.

Storage/Stability

Specimen Type Temperature Time
Plasma Refrigerated 2 days
  Frozen (preferred) 13 weeks

 

Reject Due To

  • Freezing and thawing more than once
  • Samples with apparent contamination
  • Specimens received at room temperature

Reference Values

3.2 - 10.7 µmol/L

Day(s) Test Set Up

Daily

Test Classification and CPT Coding

83090 - Homocysteine

LOINC Code Information

Reporting Name LOINC Code
Homocysteine 13965-9