Serum Reagin Antibody (Syphilis Serology, Qualitative)
This test detects antibodies called reagin in your blood that may indicate past or current exposure to syphilis. Reagin is an antibody response to the syphilis bacterium, Treponema pallidum.
["This test helps doctors check for syphilis infection by looking for immune system markers in your blood."]
Key facts at a glance
- LOINC
- 22463-4
- Short code
- Reagin Ab Ser Donr Ql
- Synonyms
- Reagin Ab Ser Donr Ql
- Category
- chemistry
- Sample
- serum
- Container
- Red-top tube (SST)
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 5 mL
- Stability
- Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
What This Test Measures
The test measures the presence of reagin antibodies, which are a type of immune response that can develop after exposure to syphilis bacteria. These antibodies are not specific to syphilis but are often detected in its presence. The test is qualitative, meaning it only tells you whether antibodies are present or not, rather than providing a precise amount.
Why It’s Done
Doctors may order this test if you have symptoms of syphilis, such as sores, rashes, or other signs, or if you have risk factors like multiple sexual partners, unprotected sex, or exposure to syphilis. It can also be used as part of routine screening in certain high-risk groups.
How It’s Performed
A blood sample is drawn from a vein in your arm. The sample is then tested in a lab to detect the presence of reagin antibodies using an immunoassay method, which identifies the antibodies without measuring their exact concentration.
What the Results Mean
A positive result means reagin antibodies are present, suggesting a possible syphilis infection. A negative result means no detectable antibodies were found, but this does not definitively rule out syphilis. Further testing may be needed for confirmation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Reagin antibodies are not specific to syphilis but are commonly detected in its presence. While they can indicate exposure, they may also appear in other infections or inflammatory conditions. A positive test should be followed up with specific treponemal tests (like T. pallidum antibodies) for accurate diagnosis. Early treatment with antibiotics can effectively manage syphilis if detected early.
Short name
Syphilis Antibody Test (Qualitative)
Frequently asked questions
What does a positive result mean?
Can I get syphilis if my test is negative?
How often should I get this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.
This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.
This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.
If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.
Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy