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Test Code RF Rheumatoid Factor

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Li-Heparin Mint Green Top

Other Acceptable specimens: Serum/Gold Top, Serum/Red Top

Specimen Stability

Storage Temperature

Stability

Room temperature

24 hours

Refrigerated

3 days

Frozen

4 weeks 

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent room temperature at 15-25oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours.

Reference Values

 

Test

Age

Sex

Reference Range

Rheumatoid Factors

All

All

≤ 14 IU/mL

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour 

Routine Turnaround Time: 4 hours

Testing Schedule: 24/7

Clinical Indications

Measurements may be used as an aid in the diagnosis of rheumatoid arthritis.

Methodology

Immunoturbidimetric Assay (Roche Diagnostics)

CPT Codes

86431

LOINC Codes

TBD

Synonyms/Keyword Search

RF

Last Review Date

4/18/2025

Critical Values

Not applicable

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Test Components

Rheumatoid Factors

Additional Information

Rheumatoid factors are also found in other inflammatory rheumatic diseases and in various non-rheumatic diseases. They are also found in clinically healthy persons over 60 years of age.