Chlamydia Antibody, Qualitative (Serum/Plasma)
This test detects antibodies to *Chlamydia trachomatis*, a bacterium that can cause sexually transmitted infections (STIs) like chlamydia. It helps identify if your immune system has ever been exposed to the infection.
["This test checks for past or current exposure to chlamydia, not an active infection at the time of testing."]
Key facts at a glance
- LOINC
- 75757-5
- Short code
- CHLCF
- Synonyms
- Chlamydia Ab Ser Ql CF
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum collection tube or serum separator tube (SST)
- Units
- N/A
- Ref low
- 16
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- comp-fix
- CPT
- 86631
- SNOMED
- 122548005
- Specimen volume
- 1-2 mL of serum
- Stability
- Room temperature: 8 hours. Refrigerated (2-8°C): 7 days. Frozen (-20°C or below): 30 days. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms of an STI (e.g., unusual discharge, pain during urination), a history of chlamydia, or if you’re part of a screening program for sexually active individuals. It’s also used during pregnancy to assess risk for complications.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample (usually from your arm) in a serum or plasma tube. The test is drawn by a phlebotomist in a clinical setting, and results are typically available within a few days.
What the Test Results Mean
A positive result means your blood contains antibodies against chlamydia, suggesting past exposure. A negative result indicates no detectable antibodies at this time. However, a negative result doesn’t guarantee you’re free of infection—active chlamydia can still be present without antibodies.
What If Results Are Abnormal
If your test is positive, follow-up testing (e.g., a nucleic acid amplification test for active infection) may be needed. Treatment depends on your symptoms and provider’s assessment. If you’re pregnant, this test helps guide prenatal care to prevent complications like preterm birth.
Reference range
Negative: No detectable Chlamydia antibodies. Positive: Antibody titer >= 1:64 suggests current or recent infection. Titer of 1:16-1:32 may indicate past exposure or early infection.N/A
No fasting required. Patients should inform their healthcare provider of any recent antibiotic therapy, immunosuppression, or vaccination history which may affect antibody response.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
◆Associated findings1
Short name
Chlamydia Antibody (Qual)
Frequently asked questions
What does a positive result indicate?
Can a negative result mean I’m not infected?
How often should I get retested?
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