TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: FRGAM    
Rheumatoid Factor (RF); IgG, IgA & IgM

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

Rheumatoid Factor (RF) levels IgG:

Negative: <20 EU/mL

Borderline/Equivocal: 20-25 EU/mL

Positive: >25 EU/mL

 

Rheumatoid Factor (RF) levels IgA:

Negative: <20 EU/mL

Borderline/Equivocal: 20-25 EU/mL

Positive: >25 EU/mL

 

Rheumatoid Factor (RF) levels IgM:

Negative: <10 IU/mL

Borderline/Equivocal: 10-12.5 IU/mL

Positive: >12.5 IU/mL

Interpretation Provides information to assist in interpretation of the test results

The presence of abnormal levels of all three rheumatoid factor (RF) isotypes has a specificity of 99% for Rheumatoid Arthritis. IgA-RF alone can occur in Henoch Schoenlein purpura. RF in any isotype combination may be found in hepatitis C, Sjogren Syndrome, and other chronic infections.

 

Borderline/Equivocal RF results warrant redraw & retesting to confirm.