Rheumatoid Factor
Immunology and Allergy Overview / Directory
Purpose of the test
Rheumatoid factor (RF) is one of a group of autoantibodies with specificity for the Fc region of human IgG. RF is usually taken to be the classical RF, IgM anti-IgG. There are IgA and IgG anti-IgGs. 70% of patients with rheumatorid arthritis (RA) have classical RF are termed seropositive RA. The remainder are termed seronegative RA. It is important to remember there is no specific test for RA and that RF is detectable in many other clinical scenarios.
Reference Range
Normal limit < 20 iu/mL
Sample Requirements
Serum is preferred, as is measurement on day of venepuncture. EDTA and heparin plasmas are acceptable. All samples must show no signs of deterioration and lipaemic samples should be avoided.
Storage and Transport
Samples may be stored at 4°C prior to analysis
Turnaround Time
1 working day
Time Limit for Extra Tests
Five days
Factors affecting results or interpretation
All tests are compromised by prolonged transit times. For this reason, date of bleed and date of postage must be provided with each request.
Price
Price available on application - please contact adrianturner1@nhs.net. Discounts could be available for significant workloads.
Contacts
John Cazabon or Rosemary Ebling, Lead Biomedical Scientists
T 020 3299 1559
