Skip to content

Chlamydia pneumoniae IgG Antibody (Serum) - Immunoassay

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

This test measures the level of antibodies in your blood that your immune system produces in response to *Chlamydia pneumoniae*, a type of bacteria that can sometimes affect your lungs and heart. Antibodies help your body recognize and fight infections.

Quick summary

["This test helps doctors assess past exposure to *Chlamydia pneumoniae* and may support diagnosis of related respiratory or cardiovascular conditions."]

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

Key facts at a glance

LOINC
6916-1
Short code
C psittaci IgG Titr Ser IF
Synonyms
C psittaci IgG Titr Ser IF
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Ref low
8
Ref high
61
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
CPT
82977
SNOMED
3110003
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 Does This Test Measure?

The test detects IgG antibodies, which are part of your immune system’s memory response. These antibodies develop after your body has been exposed to *Chlamydia pneumoniae* (or a similar organism) in the past. Unlike IgM antibodies (which appear shortly after infection), IgG antibodies linger longer and indicate a past or ongoing immune response.

Why Might You Need This Test?

Your healthcare provider may order this test if you have symptoms like persistent cough, chest pain, or fatigue—especially if other tests (like a chest X-ray or lung function tests) suggest possible *Chlamydia pneumoniae* involvement. It can also be used in research or to monitor chronic conditions linked to long-term exposure.

What Does a Positive Result Mean?

A positive result suggests your body has encountered *Chlamydia pneumoniae* at some point, meaning you likely had an infection (or exposure) in the past. However, this does not always mean you are currently infected or sick. It may indicate a history of exposure that could contribute to conditions like chronic bronchitis or heart disease.

What Does a Negative Result Mean?

A negative result means your blood does not currently show detectable IgG antibodies to *Chlamydia pneumoniae*. This could mean you’ve never been exposed or that your immune system has cleared the infection. However, false negatives are possible, especially if the test was taken too early after exposure.

Reference range

Adult males: 8-61 U/L; Adult females: 5-36 U/LN/A

Specimen: serum

No special preparation required. Avoid fatty meals before the test if possible.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

While IgG antibodies alone are not diagnostic for an active infection, they can support a broader evaluation of respiratory or cardiovascular health, particularly in patients with chronic symptoms. Some studies link *Chlamydia pneumoniae* to conditions like chronic obstructive pulmonary disease (COPD) or atherosclerosis, though more research is needed to confirm causality. This test is often used in research or specialized clinical settings rather than routine diagnosis.

Short name

IgG Antibody to Chlamydia pneumoniae

Frequently asked questions

Can this test help diagnose an active infection with *Chlamydia pneumoniae*?
No, this test primarily detects past exposure. For diagnosing an active infection, your doctor may use culture, PCR testing, or other specialized methods that look for the bacteria itself or recent infection markers (like IgM antibodies).
What if my test results are positive but I don’t have symptoms?
A positive result just means your body has encountered *Chlamydia pneumoniae* before. You may not feel sick now, but it’s important to discuss your symptoms and overall health with your doctor. Some people develop long-term effects (like chronic lung issues) even without obvious symptoms.
How long do IgG antibodies stay in my blood after infection?
IgG antibodies can persist for years or even decades after infection. They don’t always decrease over time, so a positive result doesn’t necessarily mean the infection is active. If you’re concerned about symptoms, your doctor may recommend follow-up testing or other evaluations.
  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