Rheumatoid Factor (RF); IgG, IgA & IgM

Category: Otology
Test Code: 011
Disease: • Sjögren's Syndrome • Rheumatoid Arthritis • Autoimmune Hearing Loss (SNHL) • Systemic Lupus Erythematosus (SLE)
Methodology: ELISA
Reference Range: IgG & IgA: Negative: <20 ; Borderline: 20-25; Positive: >25 ; IgM: Negative <7 ; Borderline: 7-9 ; Positive:>9
Units: IgG & IgA : EU/ml ; IgM: IU/ml
CPT Code: 86431(x3)
Schedule / Turnaround Time: Assay performed once per week. Report availability is within one week from the time of specimen receipt.
Specimen Requirements:

Specimen need not be refrigerated or frozen. Collect 2-3 ml of blood in a red top or serum separator tube. If possible, separate serum from clot and place into white tube provided with Immco Diagnostics’ collection kits. If separation facilities are not available, the blood can be sent in the tube used for collection.

Sample Stability:

Sample is stable at ambient temperature during shipment. If sample is stored prior to shipment, it is stable refrigerated (2-8˚C) up to five days and frozen (-20˚C or lower) up to one year.


The measurement of RF is important in the diagnosis and prognosis of rheumatoid arthritis. High levels of RF occur in sera of patients who tend to develop extra-articular complications.