Chlamydia Antibody, Serum (Qualitative Immunoassay)
This test detects antibodies in your blood that may indicate past or current infection with *Chlamydia trachomatis*, a common sexually transmitted bacterium. It helps determine if you’ve been exposed to the infection, even if symptoms haven’t appeared yet.
["This test can help identify past or current chlamydia infection, even when symptoms are absent."]
Key facts at a glance
- LOINC
- 111420-6
- Short code
- CHLSPAB
- Synonyms
- Chlamydia Ab Msmt Ser
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST) or red-top vacutainer tube without anticoagulant
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Method
- Enzyme Immunoassay (EIA) or Immunofluorescence Assay (IFA)
- CPT
- 86631
- SNOMED
- 108879003
- Specimen volume
- 1-2 mL of serum (minimum 0.5 mL)
- Stability
- Serum stable for 7 days at 2-8°C; for longer storage, freeze at -20°C or below. 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
Your healthcare provider may order this test if you have symptoms of chlamydia—such as unusual discharge, pain during urination, or pelvic pain—or if you’re at higher risk for infection, such as through sexual contact with someone who has it. It’s also part of routine screening for sexually active individuals, especially those with multiple partners.
What to Expect Before the Test
No special preparation is needed. You’ll provide a blood sample from a vein in your arm, similar to other blood tests. The process takes a few minutes, and you can return to your normal activities afterward.
What the Test Results Mean
A positive result means your blood contains antibodies against chlamydia, suggesting past or current infection. A negative result means no detectable antibodies were found in this sample. Follow-up testing or additional questions may be needed if symptoms persist or if you’re at ongoing risk.
What Happens Next
If your test is positive, your provider will discuss next steps, which may include treatment (often with antibiotics) and follow-up testing. If negative, they may recommend retesting if you’re at ongoing risk or have symptoms.
Reference range
Negative: <1:64 titer. Positive: ≥1:64 titer or as reported by the performing laboratory based on the assay-specific cutoff.N/A
No special patient preparation required. Fasting is not necessary. Patients should inform their healthcare provider of any current antibiotic therapy, as it may affect antibody response and interpretation.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Clinical Significance
Short name
Chlamydia Antibody Screen
Frequently asked questions
What does a positive result mean?
What does a negative result mean?
Can 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