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Test Code RF Rheumatoid Factor

Additional Codes

Epic: LAB206

Specimen Required

Specimen Type: Serum

Collection Container/Type

Preferred: Serum gel

Acceptable: Red top

Submission Container/Tube: Plastic vial

Specimen Volume: 3 mL

Collection Instructions: Centrifuge and separate cells after clot formation and within 4 hours of collection. 

Specimen Minimum Volume

0.25 mL

Specimen Stability

Room temperature: 24 hours

Refrigerated: 3 days

Frozen: 1 month

Reference Range

<30 IU/mL

Rejection Due To

Unlabeled, mislabeled, wrong tube type, hemolyzed, visually lipemic, QNS, exceeds specimen/stability requirements.

Report Available

Same day

Clinical Significance

Rheumatoid factor (RF) is an autoantibody against human immunoglobulin G (IgG) commonly present at a high concentration in sera of patients with certain conditions, particularly in patients with rheumatoid arthritis.

The measurement of rheumatoid factor is useful in evaluating the diagnosis, effects of therapy, and prognosis of diseases such as rheumatoid arthritis, systemic lupus erythematosus, Sjögren's syndrome, cryoglobulinemia, and chronic hepatopathy. This assay is designed to accurately and reproducibly measure serum rheumatoid factor using agglutination.

Method Name



nterferon Alfa-2a and methotrexate may decrease serum rheumatoid factor concentration.

Methyldopa, oral contraceptives, and oxyphenisatin may increase serum rheumatoid factor levels.

Nonsteroidal anti-inflammatory drugs may decrease or have no significant effect on serum rheumatoid factor levels.

Day(s) Performed