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Rheumatoid Factor


The RF test measures the decrease in light transmitted due to interference of suspended complexes formed during an antigen-antibody reaction.

Test Utility

This is useful as an indicator of autoimmune rheumatic diseases, as well as in non-rheumatic diseases.

Specimen Collection and Preparation

Serum or plasma sample in the following tubes:

  • Preferred Sample: Serum separator tube (gold or tiger top)

  • Acceptable: Lithium/Sodium Heparin plasma (green top)

  • Acceptable: EDTA plasma (lavender top)

Specimen Storage and Stability

Serum or plasma should be separated from the cells within 2 hours.

Store serum or plasma at the following temperatures:

  • Room temperature: Up to 24 hours

  • Refrigerated: 2°C to 8°C for up to 8 days

  • Frozen: -20°C or lower up to 3 months

Specimen Rejection

  • Insufficient sample volume

  • Sample not stored at proper temperature

  • Frozen whole blood

  • Severely hemolyzed samples

  • Severely lipemic specimens

  • Specimen labeled incorrectly or not labeled

Reference Pages


Monday – Saturday

Result available within 24 hours of receipt in laboratory

NOTE: Specimens are refrigerated (2-8°) for 7 days before disposal


Vibra Health Laboratory

1307- A, Allen Dr

Troy, MI 48083

(248) 846-0663

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