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UF Health University of Florida
Pathology Laboratories UF Path Labs - Department of Pathology
Results Portal

Rheumatoid Factor, Quantitative

Additional Information:


UFHPL Epic order code: LAB206

CPT Code(s):

86431

Specimen Requirements:

Type: Serum or plasma

Container/Tube: Serum gel or heparinized plasma

Sample Volume: Submit full tubes.

Minimum volume: 0.5 mL serum or plasma

Preparation:

  1. Send specimens in their original tubes.
  2. Centrifuge tubes if there is a delay in transport of more than 1 hour.
Storage:

  • Samples are stable for up to 1 day at 15 – 25°C.
  • Samples are stable for up to 8 days at 2 – 8ºC.

Unacceptable Conditions: Samples with moderate or marked hemolysis will be rejected.

Specimen Retention Time: 5 days

Use:

Higher titres of rheumatoid factor (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; however, RF is a non-specific test, and a positive RF is observed in 1 to 5 percent of the healthy population at low titres and in 15 to 20 percent of elderly subjects with other chronic disease states. Similarly, a negative result does not exclude RA. Approximately 25 percent of patients with a diagnosed case of RA may present with a negative result for RF.

Methodology:


Immune complexes formed in solution scatter light in proportion to their size, shape and concentration. Turbidimeters measure the reduction of incidence light due to reflection, absorption or scatter. The decrease in light intensity transmitted through particles suspended in solution is a result of complexes formed during the immunological reaction between the RF of the patient serum and the anti-RF IgG antibodies coated on the latex particles. (Package Insert, OSR Special Chemistry, BAOSR6x105.05;2012-10)

Reported:


Within 24 hours

Reference Values:

= 14 IU/mL