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Anti-Cardiolipin Phospholipid Antibody (IgG) - Serology

Published: August 9, 2026Updated: August 15, 2026

This test measures the presence of antibodies against cardiolipin, a phospholipid found in cell membranes, which may be linked to certain autoimmune conditions.

Quick summary

["Helps assess potential autoimmune or inflammatory conditions by detecting unusual immune responses."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 15, 2026Editorial policy

Key facts at a glance

LOINC
51810-0
Short code
COXPH1
Synonyms
C burnet Ph1 IgG Ser IA-aCnc
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube; serum aliquot tube for transport
Units
N/A
Ref low
0
Ref high
1
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Immunoassay (Enzyme-linked immunosorbent assay or Chemiluminescent immunoassay)
CPT
86638
SNOMED
313323005
Specimen volume
1 mL serum (minimum 0.5 mL)
Stability
Stable at room temperature for 24 hours; refrigerated at 2-8°C for 7 days; frozen at -20°C or below for up to 4 weeks; avoid repeated freeze-thaw cycles
Hemolysis max
100
Lipemia max
100
Icterus max
50
TAT
24–72 hours
Order
routine

What This Test Measures

This test detects IgG antibodies that target cardiolipin, a component of cell membranes. Cardiolipin is often associated with autoimmune disorders, including lupus and other connective tissue diseases. The test helps identify whether your immune system is producing antibodies against this substance, which may indicate an underlying inflammatory or autoimmune process.

Why It Might Be Ordered

Your healthcare provider may order this test if you have symptoms suggestive of autoimmune diseases, such as joint pain, unexplained fatigue, or other signs of inflammation. It may also be used in conjunction with other tests to evaluate conditions like antiphospholipid syndrome or lupus.

Sample Collection and Preparation

A blood sample is drawn from a vein in your arm. The blood is processed to separate serum, which is then tested for the presence of cardiolipin antibodies. This test requires no special preparation, but fasting may be recommended by your provider depending on other tests ordered.

What to Expect During the Test

The procedure is quick and typically painless. You may feel a slight pinch when the needle is inserted, but most people tolerate it well. Afterward, you can resume normal activities immediately.

Reference range

Negative: <1:200; Equivocal: 1:200; Positive: >1:200 (titers may vary by laboratory methodology). Phase I IgG titer >1:800 is suggestive of chronic Q fever infection.N/A

Specimen: serum

No fasting required. No special patient preparation is needed. Acute and convalescent serum samples (drawn 3-6 weeks apart) are recommended to demonstrate seroconversion or rising titers for diagnosis of acute Q fever.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Elevated levels of anti-cardiolipin antibodies can be associated with autoimmune diseases, such as systemic lupus erythematosus (SLE) or antiphospholipid syndrome (APS). These conditions may increase the risk of blood clots, miscarriages, or other complications. While the presence of these antibodies does not definitively diagnose an autoimmune disorder, they can guide further evaluation and treatment planning.

Short name

Anti-Cardiolipin Antibody (IgG)

Frequently asked questions

What does a positive result mean?
A positive result indicates the presence of IgG antibodies against cardiolipin, which may suggest an autoimmune or inflammatory process. However, this alone does not diagnose a specific condition. Your healthcare provider will consider the result alongside other clinical findings and tests to determine the next steps.
Can this test be used to diagnose lupus or other autoimmune diseases?
This test is often used as part of a broader evaluation for autoimmune conditions, including lupus or antiphospholipid syndrome. While it can provide important clues, no single test confirms a diagnosis. Other tests and clinical assessments are typically needed for a definitive diagnosis.
How often should I get this test?
The frequency of testing depends on your medical history, symptoms, and ongoing treatment. Your healthcare provider will determine the best schedule based on your individual needs and may recommend retesting if symptoms change or if further evaluation is required.
  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 15, 2026. · Read our editorial policy