What is this test?
HLA-B27 is an inherited variant of a protein on cells of the immune system. It is more common in some inflammatory diseases of the spine, joints and eyes.
Why might it be ordered?
- For long-term inflammatory pain in the back, sacroiliac joints or recurrent uveitis.
- To supplement the evaluation of spondyloarthritis with appropriate symptoms and imaging findings.
What sample is needed?
Venous blood is taken. A cell marker or associated genetic variant is tested according to the method.
How should you prepare?
Tell the laboratory about all medicines, hormone treatments, vitamins and supplements you take. Do not stop or change treatment unless your clinician tells you to. Follow any instructions about fasting and the time of collection.
How should you understand the result?
A positive result means you carry HLA-B27, but most carriers do not develop the associated disease. A negative result does not rule it out completely. Your result is interpreted using the reference interval on the laboratory report and in the context of your symptoms, medical history and other test findings.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.