Human Leukocyte Antigen B27 Test-Why am I having this test?

The human leukocyte antigen B27 (HLA-B27) test is performed to help your health care provider diagnose certain autoimmune diseases, especially an autoimmune disease called ankylosing spondylitis.

Autoimmune diseases are caused by an abnormality in your body’s defense (immune) system. Normally, your immune system attacks germs and other things that can make you sick. When you have an autoimmune disease, your immune system attacks the normal cells of your body instead.

Ankylosing spondylitis causes long-term (chronic) pain and stiffness in the spine and hips and can also affect other parts of the body, such as the eyes and gastrointestinal tract.

What is being tested?

This test checks your blood for the presence of HLA-B27, which is a protein found on the surface of white blood cells. HLA-B27 is commonly found in people who have ankylosing spondylitis.

What kind of sample is taken?

A blood sample is required for this test. It is usually collected by inserting a needle into a blood vessel.

How are the results reported?

Your test results will be reported as either positive or negative for the presence of HLA-B27 in your blood.

What do the results mean?

• A negative result means that you are less likely to have ankylosing spondylitis or certain other autoimmune diseases. However, having a negative result does not mean that you do not have one of these diseases.
• A positive result means that you are more likely to have:
  • Ankylosing spondylitis.
  • Other autoimmune diseases, such as:
    • Rheumatoid arthritis.
    • Reactive arthritis.
    • Psoriasis or psoriatic arthritis.
    • Inflammation of the eyes (uveitis).
    • Inflammatory bowel disease.

HLA-B27 is normally found in a small number of people without a disease. Having HLA-B27 does not always mean that you have an autoimmune disease. Your health care provider will use these test results along with other test results and your medical history to make a diagnosis.

Talk with your health care provider about what your results mean.

Questions to ask your health care provider

Ask your health care provider, or the department that is doing the test:

• When will my results be ready?
• How will I get my results?
• What are my treatment options?
• What other tests do I need?
• What are my next steps?

Summary

• The human leukocyte antigen B27 (HLA-B27) test is performed to help your health care provider diagnose a condition called ankylosing spondylitis.
• Ankylosing spondylitis causes long-term (chronic) pain and stiffness in the spine and hips and can also affect other parts of the body, such as the eyes and gastrointestinal tract.
• A negative result means that you are less likely to have ankylosing spondylitis, while a positive result means that you are more likely to have this condition or another autoimmune condition.
• Talk with your health care provider about what your results mean.