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Chlamydia IgG Antibody (Serum) – Screening Test

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

This test detects antibodies to *Chlamydia trachomatis*, a bacterium that can cause infections like sexually transmitted infections (STIs) or eye/infection complications in newborns. It helps identify past exposure rather than active infection.

Quick summary

["This test checks for past exposure to chlamydia, not current infection."]

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

Key facts at a glance

LOINC
21185-4
Short code
Chlamydia IgG Ser Ql
Synonyms
Chlamydia IgG Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What This Test Measures

The test looks for IgG antibodies in your serum. These antibodies develop after your body has encountered *Chlamydia trachomatis* and are a sign of past infection, even if symptoms were never present. Unlike IgM antibodies, IgG can remain detectable for months or years.

Why It’s Done

Your healthcare provider may order this test if you have risk factors for chlamydia (e.g., multiple sexual partners, unprotected sex) or if you’re part of a screening program. It’s not used to diagnose active infections but can help assess exposure history.

How It Works

A blood sample is drawn from a vein, and the serum (liquid part) is tested for IgG antibodies using an immunoassay method. The result indicates whether your immune system has recognized chlamydia previously.

What to Expect Before the Test

No special preparation is needed. Wear comfortable clothing, and arrange for someone to drive you home if needed, as you may feel lightheaded after the blood draw.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

IgG Chlamydia Antibody

Frequently asked questions

Why might this test result matter?
A positive result suggests past exposure to chlamydia but does not confirm current infection. It may prompt further testing (e.g., urine or swab tests) if active symptoms or risk factors are present. A negative result means no detectable IgG antibodies were found at this time.
How long do results take?
Results are typically available within 1–3 business days, depending on your lab’s processing time.
Can I get this test at home?
No, this test requires a blood sample collected by a healthcare professional in a clinical setting.
  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