Some Basic Information about HLA B27 Lab Test
The HLA-B27 Lab Test is a blood test that detects the presence of the HLA-B27 antigen, a protein found on the surface of certain cells. HLA-B27 is associated with an increased likelihood of some inflammatory conditions, particularly a group of disorders called spondyloarthritis.
What Is the HLA-B27 Lab Test?
HLA-B27 stands for Human Leukocyte Antigen B27. Human leukocyte antigens are proteins that help the immune system distinguish the body's own cells from foreign substances.
The HLA-B27 test checks whether the HLA-B27 antigen is present in a blood sample. It is commonly used when a healthcare professional is evaluating symptoms such as persistent joint pain, stiffness or swelling.
Importantly, HLA-B27 is not a disease by itself. Some healthy people have HLA-B27 and having a positive result does not mean that a person definitely has an autoimmune or inflammatory disease.
Why Is the HLA-B27 Test Done?
A healthcare provider may recommend an HLA-B27 Blood Test when certain inflammatory joint conditions are suspected.
It may be useful when evaluating conditions such as:
- Ankylosing spondylitis
- Axial spondyloarthritis
- Reactive arthritis
- Psoriatic arthritis
- Arthritis associated with inflammatory bowel disease
- Sacroiliitis
- Certain types of uveitis
HLA-B27 testing is generally interpreted together with symptoms, physical examination and other investigations rather than being used alone to make a diagnosis.
HLA-B27 and Ankylosing Spondylitis
HLA-B27 is particularly associated with ankylosing spondylitis, an inflammatory form of arthritis that mainly affects the spine and sacroiliac joints.
Although many people with ankylosing spondylitis have HLA-B27, most people who carry HLA-B27 do not develop ankylosing spondylitis. The presence of HLA-B27 therefore indicates an association or increased risk rather than confirming the disease.
What Does a Positive HLA-B27 Result Mean?
A positive HLA-B27 result means that the HLA-B27 antigen was detected in the blood.
A positive result may support the evaluation of certain inflammatory conditions, particularly when a person has symptoms suggestive of spondyloarthritis.
However, a positive HLA-B27 test does not by itself diagnose ankylosing spondylitis or another autoimmune condition. A healthcare provider may consider the result alongside symptoms, medical history, examination and other laboratory or imaging tests.
What Does a Negative HLA-B27 Result Mean?
A negative result generally means that HLA-B27 was not detected.
However, a negative HLA-B27 result does not completely rule out inflammatory arthritis or related conditions. Some people with spondyloarthritis can be HLA-B27 negative.
Therefore, test results should always be interpreted in the context of the person's symptoms and other clinical findings.
What Other Tests May Be Done Along With HLA-B27?
Depending on the symptoms and suspected condition, a healthcare provider may recommend additional tests, such as:
These tests can provide additional information about inflammation, autoimmune conditions and changes in the joints or spine.
Is Fasting Required for the HLA-B27 Test?
No special preparation or fasting is generally required for an HLA-B27 blood test.
A blood sample is usually collected from a vein in the arm or hand.
If your doctor has prescribed other tests along with HLA-B27, follow the preparation instructions provided for those tests.
How Is the HLA-B27 Blood Test Performed?
The HLA-B27 test requires a blood sample.
A healthcare professional generally:
- Cleans the skin over a vein.
- Inserts a small needle.
- Collects the required blood sample into a tube.
- Removes the needle.
- Applies pressure to the collection site.
The sample is then sent to the laboratory for testing.
When Might a Doctor Recommend HLA-B27 Testing?
HLA-B27 testing may be considered when a person has symptoms that could suggest inflammatory arthritis, such as:
- Persistent lower back pain
- Back stiffness
- Joint pain or swelling
- Pain around the sacroiliac joints
- Symptoms suggesting inflammatory arthritis
- Certain forms of eye inflammation
The test may be particularly useful when the clinical picture suggests a condition belonging to the spondyloarthritis group.
Frequently Asked Questions
1. What is the HLA-B27 Lab Test?
The HLA-B27 Lab Test is a blood test that detects whether the HLA-B27 antigen is present. It is commonly used during the evaluation of certain inflammatory joint and autoimmune-related conditions.
2. Does a positive HLA-B27 mean I have ankylosing spondylitis?
No. A positive result does not by itself mean that you have ankylosing spondylitis. HLA-B27 is also found in some healthy people.
3. Does HLA-B27 testing require fasting?
No. Generally, no special preparation is required for an HLA-B27 blood test.
4. What conditions are associated with HLA-B27?
HLA-B27 is associated with several conditions in the spondyloarthritis group, including ankylosing spondylitis, reactive arthritis and some forms of psoriatic or inflammatory bowel disease-associated arthritis.
5. Can HLA-B27 be negative in ankylosing spondylitis?
Yes. A person can have ankylosing spondylitis or another spondyloarthritis condition without having HLA-B27.
6. Is HLA-B27 a genetic test?
HLA-B27 is an inherited genetic variant associated with the HLA-B gene. The laboratory test detects the presence of the HLA-B27 antigen/variant rather than diagnosing a disease directly.
Conclusion
The HLA-B27 Lab Test is a useful diagnostic aid when healthcare professionals are evaluating certain inflammatory joint and spine conditions. It can provide additional information when conditions such as ankylosing spondylitis or other forms of spondyloarthritis are suspected.
However, HLA-B27 testing should not be interpreted on its own. A positive or negative result needs to be considered alongside symptoms, examination, medical history and other laboratory or imaging findings.
If your healthcare provider has recommended an HLA-B27 test, you can contact VIP Labs for laboratory testing and diagnostic services.
