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Test Code RHUF Rheumatoid Factor, LAB206

Methodology

Nephelometry

Performing Laboratory

St. Luke's Hospital Cedar Rapids

Specimen Requirements

Container/Tube:

Preferred: Green-top (lithium heparin) tube

Acceptable: Gold-top serum gel tube or plain red top tube
Specimen Volume: 0.2 mL of plasma or serum

Stability: Separate specimens within 2 hours of collection and analyze immediately

               or store at 2 – 8 °C and analyzed within 7 days. For longer storage, samples

               may be frozen at -20 °C for up to 3 months if frozen within 24 hours after collection. 

               Repeated freeze-thaw cycles should be avoided.

 

Reference Values

<15 IU/mL

Day(s) Test Set Up

Monday through Sunday

Test Classification and CPT Coding

86431

Useful For

The detection of RF is one of the criteria of the American Rheumatism Association (ARA) for the diagnosis of rheumatoid arthritis (RA), since 70 – 90% of patients with RA exhibit rheumatoid factors. Rheumatoid factors play an important role in the differential diagnosis between RA and other rheumatic diseases.

Analytic Time

STAT within 1 hour of receipt

Routine within 2 hours of receipt