Chlamydia Antibody, Qualitative Serologic Test (Serum)
This test detects antibodies to *Chlamydia trachomatis*, a common bacterial infection that can affect the reproductive system, respiratory tract, or eyes. It helps identify past or current exposure.
["This screening helps determine if you’ve been exposed to chlamydia, even if you don’t have symptoms."]
Key facts at a glance
- LOINC
- 5083-1
- Short code
- CHLACFT
- Synonyms
- Chlamydia Ab Titr Ser CF
- Category
- chemistry
- Sample
- serum
- Container
- Red-top serum tube (no anticoagulant) or serum separator tube (SST)
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Critical range
- — – 64 N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- comp-fix
- CPT
- 86631
- SNOMED
- 37738008
- Specimen volume
- 1.0–2.0 mL serum
- Stability
- Serum stable for 48 hours at 2–8 °C; for prolonged storage, freeze at -20 °C or below for up to 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 Is Done
Doctors may order this test if you have symptoms like unusual discharge, pain during urination, or pelvic pain, especially if you’re sexually active. It’s also part of routine screening for sexually transmitted infections (STIs) in certain groups, such as sexually active young adults or those with multiple partners. This test is not used to diagnose an active infection but to check for prior exposure.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample from a vein in your arm, typically done in a lab or clinic setting. The process takes a few minutes, and you may feel a slight pinch. Avoid alcohol or certain medications for 24 hours before testing if instructed by your provider.
What the Test Results Mean
A positive result means your blood contains antibodies against chlamydia, suggesting past exposure. A negative result means no detectable antibodies were found at this time. Results alone don’t confirm an active infection—additional testing (like a urine or swab test) may be needed for diagnosis.
Common Causes of False Results
False negatives can occur if the test was done too early after exposure or if the infection is very recent. False positives are rare but may happen if you have other infections or a weakened immune system. Always discuss results with your healthcare provider for accurate interpretation.
Reference range
Titer < 1:8 (Negative); 1:8–1:32 (Equivocal/Low Positive, suggest repeat in 2–4 weeks); > 1:32 (Positive, suggestive of past or current infection)N/A
No special patient preparation is required. Acute-phase serum should be collected as early as possible after symptom onset, with a convalescent sample drawn 14–28 days later to demonstrate seroconversion or titer rise.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Chlamydia is a common STI that can lead to serious health issues if untreated, including pelvic inflammatory disease (PID), infertility, or chronic pelvic pain in women. In men, it can cause epididymitis or urethritis. Early detection and treatment with antibiotics can prevent complications and reduce transmission to partners.
Short name
Chlamydia Antibody Screen (Serum)
Frequently asked questions
Will this test show if I currently have chlamydia?
How soon after exposure can I get a positive result?
Can I get this test at home?
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