Rheumatoid Factor (IgA, IgG, IgM)
Test Summary
The concentration of RF tends to be highest when the disease peaks and tends to decrease during prolonged remission. RF IgM is found in 1 to 4% of the general population. RF is present in 75% of adult RA patients with the highest incidence of RF occurring in persons over 65 years of age. Increased RF levels may also accompany a variety of acute immune responses, particularly viral infections and a number of liver diseases (infectious mononucleosis, tuberculosis, leprosy, various parasitic diseases, liver disease, sarcoidosis, and systemic lupus erythematosus).
In addition to RF IgM, raised levels of RF IgA and IgG have been reported in patients with RA. Studies from as early as 1984 suggest that the detection of RF IgA in early disease indicates poor prognosis and justifies a more aggressive course of treatment. Recently, it has become apparent that the specificity and predictive value of the RF test is substantially increased by the detection of all three RF isotypes.
Aliases
- N/A
Specimen Collection
Special Instructions
N/A
Preferred Specimen
1.8 mL serum collected in a red-top tube (no gel)
Minimum Volume
0.9 mL
Instructions
N/A
Patient Preparation
Overnight fasting is preferred
Storage
Plastic screw-cap vial
Transport Temperature
Refrigerated (cold packs)
Specimen Stability
- Room temperature: 48 hours
- Refrigerated: 8 days
- Frozen: 28 days
Limitations
N/A
Other Acceptable Specimens
N/A
Unacceptable Specimens
Gross hemolysis • Grossly lipemic • Grossly icteric • Heat treated samples • Serum separator tube (SST®)
Order Code
RFAGM
EPIC (Premier) Code
LAB5871
Includes
Rheumatoid Factor (IgA)
Rheumatoid Factor (IgG)
Rheumatoid Factor (IgM)
Rheumatoid Factor (IgG)
Rheumatoid Factor (IgM)
CPT Code
- 83520 (x3)
Billing Code
- 671033
- 671032
- 671034
CPT Statement
Methodology
Immunoassay (IA)
FDA Status
FDA Approved
Physician Attestation of Informed Consent
N/A
Testing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly VA, 20153
14225 Newbrook Drive
Chantilly VA, 20153
Reference Range
| Rheumatoid Factor (IgA) |
| ≤6 Negative |
| >6 Positive |
| Rheumatoid Factor (IgG) |
| ≤6 Negative |
| >6 Positive |
| Rheumatoid Factor (IgM) |
| ≤6 Negative |
| >6 Positive |
Setup Schedule / Expected Turnaround Time
Tuesday, Saturday; Report available: 1 - 4 days
Specimen Collection
Special Instructions
N/A
Preferred Specimen
1.8 mL serum collected in a red-top tube (no gel)
Minimum Volume
0.9 mL
Instructions
N/A
Patient Preparation
Overnight fasting is preferred
Storage
Plastic screw-cap vial
Transport Temperature
Refrigerated (cold packs)
Specimen Stability
- Room temperature: 48 hours
- Refrigerated: 8 days
- Frozen: 28 days
Limitations
N/A
Other Acceptable Specimens
N/A
Unacceptable Specimens
Gross hemolysis • Grossly lipemic • Grossly icteric • Heat treated samples • Serum separator tube (SST®)
Result Information
Methodology
Immunoassay (IA)
Testing Laboratory
N/A
Reference Range
| Rheumatoid Factor (IgA) |
| ≤6 Negative |
| >6 Positive |
| Rheumatoid Factor (IgG) |
| ≤6 Negative |
| >6 Positive |
| Rheumatoid Factor (IgM) |
| ≤6 Negative |
| >6 Positive |
Setup Schedule / Expected Turnaround Time
Tuesday, Saturday; Report available: 1 - 4 days