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HelpTest Code Soft Z0973 (Mayo RHUT) Rheumatoid Factor, Serum
Additional Codes
| Mayo code | RHUT |
| SoftLab code | Z0973 |
| Epic code | LAB6691 |
| Epic name | Rheumatoid Factor, Serum |
Reporting Name
Rheumatoid Factor, SUseful For
Diagnosis and prognosis of rheumatoid arthritis
Performing Laboratory
Mayo Clinic Laboratories in Rochester
Specimen Type
SerumAdditional Testing Requirements
An alternative or complementary assay to rheumatoid factor (RF) that has demonstrated utility in the diagnosis and assessment of rheumatoid arthritis (RA) is CCP / Cyclic Citrullinated Peptide Antibodies, IgG, Serum. Utilization of both tests can provide clinical value in the diagnosis of RA. RF is not specific and may be present in other inflammatory rheumatic diseases and nonrheumatic diseases as well as in nonaffected individuals, especially in those 60 years of age or older.
Specimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Specimen Minimum Volume
0.75 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum | Refrigerated (preferred) | 14 days | |
| Ambient | 14 days | ||
| Frozen | 14 days |
Reference Values
<15 IU/mL
Day(s) Performed
Monday through Friday
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
86431
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| RHUT | Rheumatoid Factor, S | 11572-5 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| RHUT | Rheumatoid Factor, S | 11572-5 |
Clinical Information
Rheumatoid factors (RF) are a heterogeneous group of autoantibodies associated with the diagnosis of rheumatoid arthritis (RA) but can also be found in other inflammatory rheumatic and nonrheumatic conditions. They can also be detected in some healthy individuals aged 60 years and older. Despite being nonspecific, the detection of RF or anti-citrullinated protein (anti-CCP) antibody is part of the 2010 diagnosis criterion of the American College of Rheumatology for classification of RA. More than 75% of patients with RA have an IgM antibody to IgG. The titer of RF correlates poorly with disease activity, but those patients with high titers tend to have more severe disease and, thus, a poorer prognosis than seronegative patients.
A meta-analysis compared the sensitivity and specificity of IgM RF versus anti-CCP antibody. For IgM RF, the sensitivity was 69% (CI, 65%-73%) and specificity was 85% (CI, 82%-88%). For comparison, the sensitivity for anti-CCP antibody was 67% (95% CI, 62%-72%) and 95% (CI, 94%-97%).(1) Both anti-CCP and RF are useful in the diagnosis of RA, and the use of both tests has been shown to increase diagnostic sensitivity.(2)
Interpretation
Positive results are consistent with, but not specific for, rheumatoid arthritis.
Cautions
Nonrheumatoid and rheumatoid arthritis (RA) populations are not clearly separate with regard to the presence of rheumatoid factor (RF) (15% of RA patients have a nonreactive titer and 8% of nonrheumatoid patients have a positive titer). Patients with various nonrheumatoid diseases characterized by chronic inflammation may test positive for RF. These diseases include systemic lupus erythematosus, polymyositis, tuberculosis, syphilis, viral hepatitis, infectious mononucleosis, and influenza. RF factor antibodies have been observed in non-affected individuals, particularly in patients 60 years of age or older.
Clinical Reference
1. Nishimura K, Sugiyama D, Kogata Y, et al. Meta-analysis: diagnostic accuracy of anti-cyclic citrullinated peptide antibody and rheumatoid factor for rheumatoid arthritis. Ann Intern Med. 2007;146(11):797-808
2. Chang PY, Yang CT, Cheng CH, Yu KH. Diagnostic performance of anti-cyclic citrullinated peptide and rheumatoid factor in patients with rheumatoid arthritis. Int J Rheum Dis. 2016;19(9):880-886
3. Aletaha D, Neogi T, Silman AJ, Funovits J. 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010;62(9):2569-2581
4. Smolen JS, Alethaha D, McInnes IB. Rheumatoid arthritis. Lancet. 2016;388:2023-2038
5. Roberts-Thomson PJ, McEvoy R, Langhans T, Bradley J. Routine quantification of rheumatoid factor by rate nephelometry. Ann Rheum Dis. 1985;44:379-383
Method Description
The Roche rheumatoid factors (RF-II) assay is an immunoturbidimetric assay. Latex-bound heat-inactivated IgG (antigen) reacts with the rheumatoid factor (RF) antibodies in the sample to form antigen/antibody complexes, that following agglutination, are measured turbidimetrically. Rheumatoid factors are autoantibodies that are directed against the Fc fragment of IgG. The autoantibodies occur in all immunoglobulin classes (IgA, IgG, and IgM). The Roche RF II assay measures all 3 types of autoantibodies. However, as the IgA and IgG types typically exhibit lower concentrations, the reaction against IgM autoantibodies predominates in this assay.(Package insert: RF-II, Rheumatoid Factors II. Roche Diagnostics; V 9.0 English, 02/2020)
Report Available
1 to 3 daysSpecimen Retention Time
14 daysReject Due To
| Gross hemolysis | Reject |
| Gross lipemia | OK |
| Gross icterus | OK |
Method Name
Turbidimetry
Secondary ID
603415Forms
If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.
Testing Algorithm
For more information see Connective Tissue Disease Cascade.