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Test Code RHUT Rheumatoid Factor, Serum 

Reporting Name

Rheumatoid Factor, S

Useful For

Diagnosis and prognosis of rheumatoid arthritis

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type


Additional Testing Requirements

CCP / Cyclic Citrullinated Peptide Antibodies, IgG, Serum is an alternative or complementary assay to rheumatoid factor (RF) that has also demonstrated utility in the diagnosis and assessment of rheumatoid arthritis (RA). Utilization of both of these 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 non-affected individuals especially in those 60 years of age or older.

Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.6 mL

Specimen Minimum Volume

0.5 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) and Time(s) Performed

Monday through Friday; 5 a.m.-12 a.m.

Saturday; 6 a.m.-6 p.m.

Test Classification

This test has been cleared, approved or is exempt by the U.S. 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


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 that are 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 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 do sero-negative 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)


Positive results are consistent with, but not specific for, rheumatoid arthritis.

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 Jun 5;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 Sep;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 Sep;62(9):2569-2581

4. Smolen JS, Alethaha D, McInnes IB: Rheumatoid arthritis, Lancet 2016 Oct;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

Analytic Time

Same day/1 day

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus OK

Method Name


Secondary ID



If not ordering electronically, complete, print, and send a Renal Diagnostics Test Request (T830) with the specimen.