| Test Name: |
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Rheumatoid Factor
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| Test Code(s): |
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RA / RF
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| CPT Code(s): |
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86431
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| Methodology: |
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Nephelometry
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| Request Form: |
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UWHC Laboratory Request Form (UWH 1289220, 4004202); Write in test if not on form.
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| Days Performed: |
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Daily, 24 hours.
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| Turnaround Time: |
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Stat: 1 hour.
Routine: 4 hours.
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Specimen Requirements
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| Specimen: |
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Blood
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| Collection Container: |
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Preferred: Red cap with yellow ring (SST)
Also Acceptable:
Red top
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| Collection Volume: |
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Preferred: 3 mL
Pediatrics: 1 mL
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| Volume Required: |
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Preferred: 1 mL
Pediatrics: 0.3 mL
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| Specimen Processing: |
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Centrifuge. Transfer cell-free serum to plastic vial.
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| Specimen Transport: |
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Transport specimen to UWHC Core Laboratory (B4/220). Transport with coolant pack if coming from outreach location; avoid freezing.
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| Stability: |
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Refrigerated: 7 days
Frozen: 3 months at or below -20°C (freeze within 24 hours and avoid repeated freeze-thaw cycles)
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Interpretation
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Reference Interval:
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Ages 0 days and up: less than 15 IU/mL
Note: Assay performance not established for pediatric population.
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| Additional Information: |
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A negative result does not exclude rheumatoid arthritis. Approximately 25% of patients with a diagnosed case of rheumatoid arthritis may present with a negative result for RF.
Certain non-rheumatoid conditions, connective tissue disorders and a variety of other disease states such as hepatitis may elicit a positive RF test.
Autoimmune antibodies common with other systemic autoimmune diseases were not assessed.
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