Understanding Lab Tests for Reactive Arthritis
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Reactive arthritis is an inflammatory condition that develops as a reaction to an infection in another part of the body, commonly affecting joints, eyes, skin, and the urinary tract. While there is no single blood test that directly diagnoses reactive arthritis, genetic testing plays a crucial role in assessing risk factors and supporting the diagnostic process.
Top Recommended Test
HLA-B27 Antigen
This test specifically identifies the HLA-B27 antigen, a genetic marker strongly associated with reactive arthritis. Individuals who test positive for HLA-B27 have a significantly greater risk of developing reactive arthritis, particularly following certain infections. This test is fundamental for risk assessment in patients with symptoms suggestive of reactive arthritis.
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The Role of Genetic Testing in Reactive Arthritis
Reactive arthritis is primarily diagnosed through clinical evaluation of symptoms and medical history. However, genetic markers, particularly the HLA-B27 antigen, are strongly associated with increased susceptibility to developing this condition. Testing for these genetic markers helps healthcare providers assess risk and better understand the likelihood of reactive arthritis in patients with compatible symptoms.
Other Relevant Tests
HLA B Low Resolution
This broader HLA-B typing test can identify the HLA-B27 variant along with other HLA-B alleles. Since a significant number of people with reactive arthritis are HLA-B27 positive, this test provides valuable genetic information for assessing susceptibility to developing inflammatory conditions including reactive arthritis.
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HLA-A, B, C, DRB1 and DQ High Resolution
This comprehensive HLA typing test provides detailed genetic profiling including high-resolution analysis of HLA-B27 and other related markers. It offers the most complete assessment of genetic factors associated with reactive arthritis development, making it valuable for thorough risk evaluation and genetic counseling.
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Understanding Your Results
A positive HLA-B27 test indicates increased genetic susceptibility to reactive arthritis, but it does not mean you will definitely develop the condition. Many people who are HLA-B27 positive never develop reactive arthritis. Conversely, some individuals without HLA-B27 can still develop the condition, though this is less common.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Reactive arthritis diagnosis requires comprehensive clinical evaluation by a healthcare provider. Always consult with a rheumatologist or other qualified healthcare professional for proper diagnosis and treatment.
