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Test Code RF Rheumatoid Factor

Performing Laboratory

Memorial Hospital Laboratory- Automated Procedures  304-388-5953       
Greenbrier Valley Laboratory 304-647-6060

Specimen Requirements

Preferred : Plasma- Mint Green, Dark Green Lithium Heparin

Acceptable: Serum- SST gold top, red top

Allow SST or red top to completely clot

Spin and physically separate plasma/serum from contact with cells as soon as possible

4 mL of plasma/serum (minimum 2 mL)

Specimen Rejection

  • Improperly labeled, collected, stored, and transported
  • Quantity not sufficient

Storage and Stability

Room temperature 20-25oC 1 day
Refrigerated 4-8oC 8 days
Frozen <-20oC 3 months

Reference Values

Negative:  < 14 IU/mL

Positive: >14 IU/mL

Higher titres of RF are more specific for the diagnosis of rheumatoid arthritis (RA)

and are more common in patients with rapidly progressive joint destruction and in

those with extraarticular manifestations such as subcutaneous rheumatic nodules.

 

RF is a non-specific test and a positive RF is observed in 1 – 5% of the healthy

population at low titres and in 15 – 20% of elderly subjects with other chronic disease states.

 

Similarly a negative result does not exclude RA. Approximately 25% of patients

with a diagnosed case of RA may present with a negative result for RF.

Methodology

Turbidimetric Memorial
Two-Point Rate Greenbrier 

Days Test Set Up and Turnaround

Monday through Sunday, Continuously

AM Collection Expected by 9AM same day
Routine Expected within 24 hrs
Stat Expected within 1 hr
Timed Expected results are test dependant

CPT Coding

86430-screen

86431-titer