|
Test ID: RF
|
|
Rheumatoid Factor
|
|
|
|
Useful For
|
To help diagnose the presence of an autoimmune disease such as rheumatoid arthritis (RA).
|
|
Method name and description
|
Immunoturbidimetric assay
Immunoturbidimetric assay performed on the Roche cobas c-systems. Latex‑bound heat‑inactivated IgG (antigen) reacts with the RF‑antibodies in the sample to form antigen/antibody complexes which, following agglutination, are measured turbidimetrically.
|
|
Clinical information
|
Rheumatoid factors are a heterogeneous group of autoantibodies which aid in diagnosis of rheumatoid arthritis, but can also be found in other inflammatory rheumatic diseases and in various non‑rheumatic diseases. The detection of rheumatoid factors is a diagnostic criterion of the American College of Rheumatology for classifying rheumatoid arthritis.
|
|
|
Specimen type / Specimen volume / Specimen container
|
Specimen type: Serum, Plasma
Minimum volume of sample: 1 mL
Serum: Plain tube (red or yellow top)
Plasma: Li‑heparin tube
|
|
Collection instructions / Special Precautions / Timing of collection
|
Collect blood by standard venipuncture techniques as per specimen requirements. When processing samples in primary tubes (sample collection systems), follow the instructions of the tube manufacturer.
|
|
Storage and transport instructions
|
Storage: 1 day at 20 – 25°C
8 days at 4 – 8°C;
3 months at ‑20 °C
Transport: 4-25°C
|
|
Specimen Rejection Criteria
|
Grossly hemolyzed, icteric and lipemic samples, wrong collection container, insufficient sample.
|
|
|
Biological reference intervals and clinical decision values
|
|
|
|
Factors affecting test performance and result interpretation
|
In very rare cases, gammopathy, in particular type IgM (Waldenström’s macroglobulinemia), may cause unreliable results.
|
|
Turnaround time / Days and times test performed / Specimen retention time
|
Daily (24/7)
Turn-around time:
Routine: One working day
Specimen Retention: 4 days
|
|
|
