| Test Name: |
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Homocysteine
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| Test Code(s): |
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HCY / XHCYCD
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| CPT Code(s): |
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83090
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| Methodology: |
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Chemiluminescent Immunoassay
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| Clinical Significance: |
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Assist in diagnosis and treatment of patients suspected of having hyperhomocysteinemia and homocystinuria.
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| Days Performed: |
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Mon-Fri, dayshift.
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| Turnaround Time: |
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Routine: Next working day.
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Specimen Requirements
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| Specimen: |
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Blood
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| Collection Instructions: |
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Immediately refrigerate blood tube or place on cold-pack after collection.
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| Collection Container: |
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Preferred: Lavender top
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| Collection Volume: |
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Preferred: 4 mL
Pediatrics: 0.5 mL
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| Sample Analyzed: |
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Plasma
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| Volume Required: |
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Preferred: 1 mL
Pediatrics: 0.25 mL
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| Specimen Processing: |
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Centrifuge immediately and transfer cell-free plasma to plastic vial within 30 minutes of collection.
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| Specimen Transport: |
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Transport specimen to UWHC Core Laboratory (B4/220) immediately. Transport frozen plasma on dry ice if coming from outreach location.
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| Stability: |
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Ambient: not recommended; store in refrigerator if testing will not be performed immediately
Refrigerated: 48 hours
Frozen: -20°C for up to 13 weeks
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Interpretation
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Reference Interval:
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| Age |
umol/L |
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| 2 months-10 years |
0.0 - 8.3
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| 11 - 15 years |
0.0 - 10.3
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| 16 - 17 years |
0.0 - 11.3
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| 18 years and up |
0.0 - 13.9
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| Test Limitations: |
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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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