This test checks for a special protein, called HLA-B27, found on the surface of white blood cells. The test uses a method called PCR (Polymerase Chain Reaction) to look for the gene that makes this protein. Doctors often recommend this test if someone has symptoms like joint pain, back pain, or swelling, which could be linked to certain autoimmune diseases. Knowing if HLA-B27 is present helps doctors understand your risk for conditions like ankylosing spondylitis or other related problems. The test is simple, using a blood sample, and does not require fasting.

What it Measures

The HLA-B27 PCR test looks for the presence of the HLA-B27 gene using a sensitive laboratory method called PCR. Here’s what the test checks:

HLA-B27 Gene:
This test detects if you have the HLA-B27 gene, which tells your body to make the HLA-B27 protein. This protein sits on the surface of your white blood cells and helps your immune system tell the difference between your own cells and foreign invaders.
Qualitative Result:
The PCR method can show whether this gene is present or not. It does not measure the amount, but simply tells if the gene is there (positive) or not (negative).
Why This Matters:
Having the HLA-B27 gene does not mean you will get a disease, but it does increase your risk for certain autoimmune conditions. These include:

Ankylosing spondylitis (a type of arthritis that mainly affects the spine)
Reactive arthritis (joint pain and swelling triggered by an infection)
Juvenile idiopathic arthritis (arthritis in children)
Psoriatic arthritis (arthritis linked to psoriasis)
Inflammatory bowel diseases like Crohn’s disease

PCR Technique:
The PCR (Polymerase Chain Reaction) method is very accurate and can find even small amounts of the HLA-B27 gene in your blood. This makes it more reliable than older methods for detecting the gene.
Result Reporting:
The test result is usually reported as “positive” (gene found) or “negative” (gene not found). Sometimes, a quantitative PCR may estimate the amount of gene present, but most routine tests are qualitative.

Why is it Important

Helps Diagnose Autoimmune Diseases:
The presence of HLA-B27 can help doctors diagnose certain autoimmune disorders, especially if you have symptoms like back pain, joint swelling, or eye inflammation. It is an important clue for conditions such as ankylosing spondylitis and reactive arthritis.
Assists in Early Detection:
Some autoimmune diseases develop slowly and may not show clear signs at first. This test helps doctors find out if you are at higher risk, so they can monitor your health more closely and start treatment early if needed.
Guides Treatment Decisions:
Knowing your status can help your doctor decide on the best treatment plan and monitor how the disease may progress. It also helps in planning regular check-ups to prevent complications.
Family and Genetic Counseling:
Since this gene can run in families, this test can be useful if you have a family history of related diseases. It helps in understanding your risk and planning for early intervention if symptoms appear.
Supports Organ Transplant Matching:
In some cases, the test is used to help match organ donors and recipients, as matching HLA types can reduce the risk of transplant rejection.

When Should I Get This Test?

You may be advised to take this test if you have:

Chronic back pain, especially in the lower back that started before age 40.
Joint pain, swelling, or stiffness that does not improve with rest.
Eye inflammation (redness, pain, or blurred vision).
A family history of autoimmune diseases like ankylosing spondylitis.
Symptoms of inflammatory bowel disease or unexplained fatigue.

Interpretation of Test Results

Understanding what your results might mean is helpful, but always discuss them with a doctor for a proper diagnosis.

Result Type	What it Means
Negative	HLA-B27 gene not found. This means you are less likely to have certain autoimmune diseases, but it does not rule them out completely.
Borderline	In rare cases, results may be unclear. Your doctor may suggest repeating the test or doing other tests for confirmation.
Positive	HLA-B27 gene found. This increases your risk for certain autoimmune diseases, but does not mean you will definitely get them.

(Note: Specific normal ranges can vary slightly between labs and depending on individual factors. Always refer to the ranges provided on your report and consult your doctor.)

Additional Information

A positive result does not mean you have a disease; it only shows higher risk. Many healthy people have HLA-B27 and never develop any illness.
If your test is positive, your doctor may order more tests or imaging studies to confirm a diagnosis.
Always follow up with your doctor for advice, especially if you have symptoms or a family history of autoimmune diseases.

Test Requirements

Sample Type: Blood sample (taken from a vein in your arm).
Preparation Needed: No fasting is required. You can eat and drink as usual before the test.
Precautions: Inform your doctor about any medicines you are taking. There are no special precautions needed for this test.

FAQs

Do I need to fast before the HLA-B27 PCR test?
No, fasting is not required for this test. You can eat and drink normally before your blood sample is taken. This makes the test easy and convenient for most people.
What does a positive HLA-B27 PCR result mean?
A positive result means the HLA-B27 gene is present in your blood. This increases your risk for certain autoimmune diseases, but it does not confirm that you have one. Many people with HLA-B27 never develop any illness. Always discuss your results with your doctor for the right interpretation.
Can pregnancy affect the test results?
Pregnancy does not affect the result of this test. The test looks for a gene, which stays the same whether you are pregnant or not.
What should I do if my result is positive?
If your test is positive, consult your doctor. They may order more tests or check for symptoms to confirm if you have an autoimmune disease. Do not panic—many people with a positive result stay healthy.
Is the test only for people with joint pain?
No, this test may also be recommended if you have eye inflammation, a family history of autoimmune diseases, or symptoms of inflammatory bowel disease. It helps doctors understand your risk and plan further care.

For more information, see Netmeds Health Library: Ankylosing Spondylitis: Causes, Symptoms and Treatment

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