You can use CPT 86430 and CPT 86431 for rheumatoid factor tests. Report CPT 86430 for a qualitative Rheumatoid Factor test and 86431 if the test was quantitative. Both of the procedures are described here below, with the official long description as defined by AMA and a short version.
CPT Code 86430
Long description: Rheumatoid factor, qualitative.
Short description: Qualitative rheumatoid factor.
CPT Code 86431
Long description : Rheumatoid factor, quantitative.
Short description: Quantitative rheumatoid factor.