Test for Rheumatoid Factors Lesson 4-3 Test for Rheumatoid Factors
Rheumatoid Arthritis (RA) Autoimmune disease Joint inflammation, pain, and deformity Distinguish from other types of arthritis
Rheumatoid Arthritis (RA) Rheumatoid factors (RF) IgM directed against IgG Detect using rapid tests 75% to 85% of RA patients have elevated serum RF RF present in other conditions
Principle of RF Slide Test Latex agglutination Reagent is IgG-coated latex particles Combine patient serum with latex reagent Observe for agglutination RF (IgM) will cause agglutination
Principle of RF Slide Test
Qualitative Test for RF Safety precautions Quality assessment Specimen Serum from venipuncture Dilute serum 1:20 Procedure Diluted serum + latex reagent
Interpreting Results of RF Test Agglutination is positive (+) result Perform semi-quantitative test if 1:20 dilution is positive
Significance of Results Only serum positive at ≥1:20 is considered positive for RF Conditions other than RA can cause positive results 15% to 25% of RA patients can be negative for RF
Semi-Quantitative Test for RF Serial dilutions of patient serum Test each dilution with latex reagent Report RF titer Identify highest dilution with positive reaction Titer is reciprocal of dilution
Significance of Positive RF Test RF test not specific for RA Only 75% to 85% positive in RA patients Negative test does not rule out RA Other conditions can have ↑ RF Test can be used to follow disease course This project was funded at $3,000,000 (100% of its total cost) from a grant awarded under the Trade Adjustment Assistance Community College and Career Training Grants, as implemented by the U.S. Department of Labor’s Employment and Training Administration. Rogue Community College is an equal opportunity employer/program. Auxiliary aids and services, alternate form and language services are available to individuals with disabilities and limited English proficiency free of cost upon request. This work is licensed under a Creative Commons Attribution 4.0 International License.