HLA B27 Test

The presence of an HLA protein does not always indicate disease. An HLA-B27 test is often performed to check for ankylosing spondylitis. Healthcare providers advise this test for patients in the early stages of ankylosing spondylitis where the disease is not progressed, and the changes in vertebrae are not seen in an X-ray. This antigen is found in >90% patients with ankylosing spondylitis. However, it is usually present in 5-7% of the people without an autoimmune disease and is also helpful for detecting rheumatoid arthritis, Grave’s disease and Reiter’s syndrome. Hence, HLA findings should be correlated with patient’s symptoms. It is also done in cases of post mortem kidney transplants. 

No specific preparations are required before this test. You don't have to fast either. 

For this test, seven millilitres of blood will be drawn from a vein in your arm or hand and it will be collected in a tube usually containing heparin, a compound that prevents blood clotting. Test tubes with other anticlotting substances may also be used for collection. 

It is important to note that HLA-B27 test is a specific test that may not be offered by every laboratory. The blood sample may be sent to a reference laboratory, and it may take several days to get results.

Presence of HLA B 27 could be indicative of diseases, such as

• Ankylosing spondylitis: A disease characterised by inflammation and gradual stiffening of the joints, spine, neck and chest
• Rheumatoid arthritis: A disease affecting the lining of the joints leading to swelling and pain
• Grave’s disease: A disorder that makes the thyroid overactive
• Psoriatic arthritis: Arthritis that occurs due to psoriasis
• Ulcerative colitis: A disease causing inflammation and ulcers in the large intestine
• Crohn’s disease: A disease affecting the small intestine and characterised by swelling
• Reactive arthritis: Inflammation of the joints, eyes, urethra as well as skin lesions
• Uveitis: Inflammation of the structure of the eyes
• Sacroiliitis: Inflammation and stiffening of the sacrum and hip bones

HLA-B27 test is also used for tissue matching during organ transplants. It is not a diagnostic test but is helpful in ruling out diseases. Other tests, such as C-Reactive protein, erythrocyte sedimentation rate, rheumatoid factor and X-ray tests, should also be done to correlate with the patient’s clinical symptoms.
The test is not done as a routine test. Only persons who have symptoms indicative of autoimmune disease are checked. A positive HLA-B27 without any clinical symptoms or strong family history may not be of any clinical significance. That means, even if the person is tested having a family history, it cannot be predicted if the person will develop an autoimmune disease.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.