Rheumatoid factor
Rheumatoid factor represents a valuable tool in the differential diagnosis of rheumatic diseases.
Reference Ranges
| < 15 IU/mL | 95th percentile |
| 19 IU / mL | In a healthy population, RF values are usually expected to be < 15 IU/mL (95th percentile). In a study, a cut-off value of 19 IU/mL was defined for optimum sensitivity (82.4%) and specificity (95.9%) for rheumatoid arthritis. With 1% RA prevalence, this results in a PPV of 16.9% and a NPV of 99.8%. |
Each laboratory should check if the reference ranges are transferable to its own patient population and determine own reference ranges if necessary. For diagnostic purposes, the results should always be assessed with the patient’s medical history, clinical examinations and other findings.
For information on clinical relevance, please refer to the package insert.