Chlamydia Antibody, Qualitative (Serum/Plasma) – Fluorescent Antibody Test
This test detects antibodies in your blood that may indicate past or current infection with *Chlamydia trachomatis*, a common sexually transmitted bacterium.
["This screening helps identify potential exposure to chlamydia, though it does not confirm an active infection alone."]
Key facts at a glance
- LOINC
- 20755-5
- Short code
- CHLAG
- Synonyms
- Chlamydia Ag Fld Ql IA
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, leak-proof container for body fluid collection; transport medium or sterile tube without preservatives preferred
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 0–99 years
- Method
- Immunoassay (Enzyme Immunoassay - EIA)
- CPT
- 87320
- SNOMED
- 310861008
- Specimen volume
- 1-2 mL of body fluid
- Stability
- Refrigerated (2-8°C): up to 48 hours; Frozen (-20°C or lower): up to 7 days for delayed testing. Avoid repeated freeze-thaw cycles. If transport medium is used, follow manufacturer-specific stability guidelines.
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 24–72 hours
- Order
- routine
Why This Test Is Done
Your healthcare provider may order this test if you have symptoms like unusual discharge, pain during urination, or if you’re at higher risk for sexually transmitted infections (STIs). It’s also used as part of routine screening for sexually active individuals, especially those with multiple partners or a history of STIs.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample, usually drawn from your arm. The test looks for antibodies produced by your immune system in response to chlamydia, detected through a fluorescent antibody technique.
What the Test Results Mean
A positive result suggests you may have had past exposure to chlamydia, but it does not confirm an active infection. A negative result means no detectable antibodies were found at the time of testing. Follow-up testing or clinical evaluation may be needed if symptoms persist or risk factors apply.
When You Might Need Follow-Up
If you test positive, your provider will likely recommend further testing (e.g., urine or swab tests) to check for active infection. Treatment may be prescribed if chlamydia is confirmed, even without symptoms.
Reference range
Negative: No Chlamydia sp. antigen detected. Positive: Chlamydia sp. antigen detected, indicating active infection.N/A
No fasting required. Patient should avoid antibiotic therapy for at least 24-48 hours prior to specimen collection when possible, as antibiotics may reduce antigen detection sensitivity. For body fluid specimens, specimen collection should be performed by a qualified healthcare provider using appropriate aseptic technique.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Chlamydia is a bacterial infection that can cause serious health issues if untreated, including pelvic inflammatory disease, infertility, or complications during pregnancy. Early detection through antibody screening helps guide treatment and prevent long-term complications.
Short name
Chlamydia Antibody Screen (Fluorescent Antibody)
Frequently asked questions
How long does it take to get test results?
Can I get false positives or false negatives with this test?
Does this test detect active chlamydia infection?
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