The blood test results you've shared show
elevated levels of Rheumatoid Factor (RF) in two separate reports:
- One test shows RF = 37 IU/mL (reference: <14 IU/mL)
- Another shows RF = 73 IU/mL (also above normal)
Additionally:
- Antinuclear Antibody (ANA) is negative
- Erythrocyte Sedimentation Rate (ESR) = 4 mm/hr, which is normal
Interpretation
Rheumatoid factor is an autoantibody. A value
above 14 IU/mL is typically considered elevated. Levels of 37 and 73 IU/mL suggest a
moderate to significantly elevated RF, which can be associated with autoimmune conditions, especially:
- Rheumatoid arthritis (RA) — RF is positive in ~70–80% of RA patients¹. However, elevated RF alone is not diagnostic.
- Other autoimmune diseases — such as Sjögren's syndrome or systemic lupus erythematosus (SLE)
- Chronic infections — like hepatitis C, tuberculosis, or endocarditis can sometimes cause elevated RF².
- Healthy individuals — especially older adults, can sometimes have elevated RF with no disease³.
A negative ANA test makes conditions like
lupus or
mixed connective tissue disease less likely. Most people with
RA can have a negative ANA, so this does not rule out RA⁴.
ESR is a non-specific marker of inflammation. A low value suggests
no active systemic inflammation at the time of the test. In early or well-controlled RA, ESR can still be normal⁵.
Summary
Your results indicate:
- Elevated RF (twice confirmed), which is a potential marker for rheumatoid arthritis or another autoimmune process
- Negative ANA, reducing the likelihood of lupus or systemic autoimmune diseases
- Normal ESR, suggesting no significant current inflammation
These results are
not diagnostic on their own. Rheumatoid arthritis diagnosis requires:
- Symptoms (e.g., joint pain, swelling, stiffness lasting more than 6 weeks)
- Clinical exam findings (swollen/tender joints)
- Imaging (joint erosion or inflammation)
- Other blood markers (anti-CCP antibodies, CRP)
Next
You should consult a
rheumatologist if you have any of the following:
- Persistent joint pain, stiffness, or swelling
- Fatigue, low-grade fever, or other systemic symptoms
- Family history of autoimmune disease
They may order more tests like
anti-CCP antibodies, which are more specific for RA, and perform a detailed physical exam.
References
- van Boekel, M. A. M., Vossenaar, E. R., van den Hoogen, F. H. J., & van Venrooij, W. J. (2002). Autoantibody systems in rheumatoid arthritis: specificity, sensitivity and diagnostic value. Arthritis Research, 4(2), 87–93. The Novartis-ILAR Rheumatology Prize 2001 Osteoarthritis: from molecule to man - Arthritis Research & Therapy
- Smolen, J. S., Aletaha, D., & McInnes, I. B. (2016). Rheumatoid arthritis. The Lancet, 388(10055), 2023–2038. Redirecting
- van Zeben, D., Hazes, J. M. W., Zwinderman, A. H., Cats, A., Han, H., & Breedveld, F. C. (1992). Clinical significance of rheumatoid factors in early rheumatoid arthritis: results of a follow up study. Annals of the Rheumatic Diseases, 51(9), 1029–1035. Redirecting
