HLA-B27 Test
A blood test for the HLA-B27 gene, linked with ankylosing spondylitis.
Quick Summary
To support the diagnosis of ankylosing spondylitis and related conditions.
Presence of HLA-B27.
No preparation needed.
Overview
Most people with ankylosing spondylitis carry HLA-B27, but most carriers never develop it.
It's interpreted with symptoms and imaging.
What It Measures
HLA-B27
Present or absent.
How It's Performed
- 01
Preparation
Usually no special preparation. Tell the staff about medicines you take.
- 02
Blood sample
A small amount of blood is taken from a vein in your arm with a thin needle.
- 03
Afterwards
Press on the spot for a minute. A small bruise is common; you can go back to normal activities.
Interpreting Results & Next Steps
Discuss with Doctor
A negative result doesn't completely rule it out. Normal ranges differ between laboratories, ages and sexes; always use the range printed on your report and ask your doctor what your results mean.
If values are High:
A positive result supports the diagnosis with typical symptoms.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- HLA-B27 antigen(opens in a new tab) · MedlinePlus, US National Library of Medicine