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UW Health SMPH
American Family Children's Hospital

UW Hospital and Clinics Lab Test Directory

Test Name: Homocysteine

Test Code(s): HCY / XHCYCD

CPT Code(s): 83090

Methodology: Chemiluminescent Immunoassay

Clinical Significance: Assist in diagnosis and treatment of patients suspected of having hyperhomocysteinemia and homocystinuria.

Days Performed: Mon-Fri, dayshift.

Turnaround Time: Routine: Next working day.

Specimen Requirements

Specimen: Blood

Collection Instructions: Immediately refrigerate blood tube or place on cold-pack after collection.

Collection Container: Preferred: Lavender top

Collection Volume: Preferred: 4 mL
Pediatrics: 0.5 mL

Sample Analyzed: Plasma

Volume Required: Preferred: 1 mL
Pediatrics: 0.25 mL

Specimen Processing: Centrifuge immediately and transfer cell-free plasma to plastic vial within 30 minutes of collection.

Specimen Transport: Transport specimen to UWHC Core Laboratory (B4/220) immediately. Transport frozen plasma on dry ice if coming from outreach location.

Stability: Ambient: not recommended; store in refrigerator if testing will not be performed immediately
Refrigerated: 48 hours
Frozen: -20C for up to 13 weeks


Reference Interval:



Age umol/L    
2 months-10 years

0.0 - 8.3

11 - 15 years

0.0 - 10.3

16 - 17 years

0.0 - 11.3

18 years and up

0.0 - 13.9







Test Limitations:

S-adenosyl-methionine is an antidepressant whose molecular form is similar to S-adenosyl-homocysteine. Therapeutic levels of this drug may interfere with this assay.

Patients taking methotrexate, nicotinic acid, theophylline, nitrous oxide, or L-dopa can have falsely elevated HCY levels.

Results may be affected if patient has developed heterophillic antibodies due to exposure to animal based protein products.

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