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Treponemal Antibody Test (Serologic, Qualitative)

Published: August 9, 2026Updated: August 16, 2026

This test detects antibodies to *Treponema pallidum*, the bacterium responsible for syphilis. A reactive result means your body has mounted an immune response to this infection.

Quick summary

["A reactive treponemal test signals possible syphilis infection; next steps depend on confirmatory testing."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
75190-9
Short code
TREPONEMALTESTWASREACTIVE
Synonyms
—
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
cdc-cs
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 looks for antibodies produced by your immune system in response to *Treponema pallidum*, the bacteria that cause syphilis. These antibodies develop after infection and can remain in your blood for years, even after treatment. This test is often used as a screening tool to identify early or past exposure to syphilis.

How the Test Works

The test uses a serologic method (likely an immunoassay) to detect antibodies against *Treponema pallidum* in your blood. A reactive result indicates the presence of these antibodies, suggesting exposure to the bacteria, but does not confirm active infection alone.

Why It’s Ordered

Your healthcare provider may order this test if you have symptoms of syphilis (e.g., sores, rash, or neurological issues), a history of sexual exposure, or if you’re part of a high-risk group. It’s also used in routine screening for sexually transmitted infections (STIs).

What to Expect

The test typically involves drawing blood from a vein in your arm. The sample is sent to a lab for analysis. Results are usually available within 24–72 hours, but timing can vary by lab.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Treponemal Antibody Test

Frequently asked questions

What does a reactive result mean?
A reactive treponemal test means your blood contains antibodies to *Treponema pallidum*, indicating past or current exposure. However, this alone does not confirm syphilis. Follow-up tests (like a non-treponemal test or FTA-MS) are needed to diagnose active infection.
What if I have symptoms?
If you have symptoms like sores, rash, or neurological issues, report them to your doctor immediately. A reactive test combined with symptoms suggests syphilis, which requires prompt treatment to prevent complications.
Can I get treated if the test is reactive?
Yes, but only if a confirmatory test confirms active infection. Treatment depends on the stage of syphilis and may include antibiotics like penicillin. Always consult your healthcare provider for guidance.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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