Rheumatoid Factor

Test Code

Alias/See Also

Epic: LAB206

Preferred Specimen

Specimen Type: Serum
Collection Container: Serum gel
Specimen Volume: 3 mL

Minimum Volume

0.25 mL

Other Acceptable Specimens

Collection Container: Red top

Instructions

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

Transport Container

Plastic vial

Specimen Stability

Room temperature: 24 hours
Refrigerated: 3 days
Frozen: 1 month

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

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

Methodology

Immunoturbidimetric

Setup Schedule

Daily

Report Available

Same day

Limitations

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.

Reference Range

<30 IU/mL

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.

Performing Laboratory

Inova Laboratories

2832 Juniper Street

Fairfax, VA 22031

Last Updated: April 14, 2023
Last Review: N. Wolford, April 14, 2023

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.