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Chlamydia Antibody Titration (Serum)

Published: August 9, 2026Updated: August 16, 2026

This test measures the level of antibodies your body produces in response to *Chlamydia trachomatis*, a common sexually transmitted bacterium. It helps determine if you’ve been exposed to the infection and whether your immune system has mounted a response.

Quick summary

["This test helps assess past exposure to chlamydia and supports diagnosis or monitoring of infection-related immunity."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
22182-0
Short code
CHLAB
Synonyms
Chlamydia Ab Titr Ser
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top vacuum tube without anticoagulant
Units
N/A
Ref low
0
Ref high
1
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Complement Fixation Test (CFT) or Microimmunofluorescence (MIF)
CPT
86631
SNOMED
31364004
Specimen volume
1-2 mL of serum
Stability
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 a sexually transmitted infection (STI), such as unusual discharge, pain during urination, or pelvic pain. It may also be used as part of routine screening for STIs, especially in high-risk groups. Some providers use it to confirm exposure after potential contact with chlamydia.

What to Expect Before the Test

No special preparation is needed. You’ll provide a blood sample from a vein in your arm. The process takes a few minutes, and you can return to your normal activities afterward. If you’re pregnant, inform your provider before the test.

What the Test Results Mean

Results are reported as a **titer** (a measure of antibody concentration). A higher titer suggests stronger immune response, often indicating past exposure. However, a low or absent titer does not definitively rule out current infection—other tests (like nucleic acid amplification) may be needed for active chlamydia diagnosis.

Possible Side Effects

Most people experience mild discomfort or bruising at the injection site. Rarely, there may be swelling or redness. If you develop fever, severe pain, or signs of infection (like pus), contact your provider immediately.

Reference range

Titer <1:16; Titers ≥1:16 indicate past or current exposure; A fourfold rise in paired sera indicates recent infectionN/A

Specimen: serum

No special preparation required. Patient should be informed about the nature of the test and consent obtained if required by institution.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is primarily used to identify past exposure to *Chlamydia trachomatis*, which can inform counseling about infection risk, vaccination (e.g., for hepatitis A/B), or follow-up testing. It does not replace confirmatory tests for active infection (e.g., PCR) and may not detect recent or acute exposure. Antibody levels can fluctuate over time, so results should be interpreted in context with clinical history and symptoms.

Short name

Chlamydia Antibody Titer

Frequently asked questions

Will this test show if I have chlamydia now?
No. This test measures antibodies, which develop after exposure but may take weeks to appear. For active chlamydia, a confirmatory nucleic acid test (e.g., PCR) is typically used instead.
How long will it take to get my results?
Results are usually available within 3–5 business days, depending on your lab. Your provider will discuss them with you during your follow-up visit.
Can I take antibiotics before this test?
Yes, but inform your provider immediately. Antibiotics may alter antibody levels, affecting test accuracy. If you’ve recently taken them, your provider may need to adjust interpretation.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

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.

Medical Disclaimer

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