Chlamydia Antibody Detection by Immunoassay (Serum/Plasma)
This test checks for antibodies to *Chlamydia trachomatis*, a common bacterial infection often spread through sexual contact. Antibodies develop after infection or vaccination, helping identify past exposure.
["Detects past or potential *Chlamydia* infection through immune system markers."]
Key facts at a glance
- LOINC
- 45133-6
- Short code
- CHLMNAG
- Synonyms
- Chlamydia Ag Nph Ql
- Category
- chemistry
- Sample
- serum
- Container
- Sterile viral transport medium (VTM) or suitable transport medium for nasopharyngeal specimens; Dacron or nylon flocked swab
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Immunochromatographic assay / Enzyme Immunoassay (EIA) for detection of Chlamydia species antigens
- CPT
- 87320
- SNOMED
- 314529007
- Specimen volume
- 1 nasopharyngeal swab in transport medium
- Stability
- Refrigerated (2-8°C): up to 48 hours; Frozen (-70°C or below): up to 7 days for extended storage
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 4–24 hours
- Order
- routine
Why This Test Matters
While this test doesn’t confirm a current infection, it can signal if your body has encountered *Chlamydia* before. This may be useful if you’ve had symptoms like unusual discharge, pain during urination, or other signs of infection, especially if you’re sexually active.
How the Test Works
Your healthcare provider will take a blood sample (serum or plasma) and use an immunoassay method to detect specific antibodies against *Chlamydia*. This detects immune system responses rather than live bacteria, so it’s not a direct infection test.
When to Get This Test
You might get this test if you’ve had symptoms of *Chlamydia* (or other STIs), if you’re part of a high-risk group (e.g., sexually active under 25, multiple partners), or if you’re pregnant and need screening. It’s also sometimes used as part of broader STI screening.
What to Expect
No special preparation is needed. You’ll have a small needle inserted into a vein (usually in your arm) to draw blood. The process takes about 5 minutes, and you can return to normal activities afterward. Results are typically ready within 1–3 days.
Reference range
Negative (Chlamydia sp antigen not detected)N/A
No special patient preparation required. Specimen should be collected prior to initiation of antimicrobial therapy when possible.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Positive results indicate your immune system has likely encountered *Chlamydia* (either through infection or vaccination). However, this doesn’t mean you’re currently infected—it only shows past exposure. If you’re concerned about symptoms, discuss them with your provider, who may recommend additional testing (like a urine or swab test) for active infection.
Short name
Chlamydia Antibody Test
Frequently asked questions
How long does it take to get results?
Can I get this test if I’m pregnant?
Does this test replace other STI tests?
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