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Anti-Cardiolipin Phospholipid Antibodies (IgG) - Immunoassay

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

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

Quick summary

["This test helps evaluate potential autoimmune or clotting-related risks."]

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

Key facts at a glance

LOINC
34716-1
Short code
COXPH1
Synonyms
C burnet Ph1 IgG Titr Ser IF
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or red-top tube without anticoagulant
Units
N/A
Ref low
100
Ref high
1
Critical range
— – 800 N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
Indirect Immunofluorescence Assay (IFA)
CPT
86638
SNOMED
395200008
Specimen volume
1-2 mL of serum (minimum 0.5 mL)
Stability
Serum stable at room temperature for 24 hours; refrigerated (2-8°C) for 7 days; frozen (-20°C or lower) for long-term storage up to several months. Avoid repeated freeze-thaw cycles.
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
48–168 hours
Order
routine

What Is This Test Measuring?

Cardiolipin is a type of fat (lipid) found in the cell membranes of certain tissues, including those in the heart and blood vessels. When the immune system mistakenly attacks these phospholipids, it produces antibodies called anti-cardiolipin antibodies. This test detects the presence of these antibodies in your blood.

Why Might Your Doctor Order This Test?

Doctors may recommend this test if you have symptoms or risk factors for autoimmune diseases (like lupus or rheumatoid arthritis) or blood clotting disorders (such as antiphospholipid syndrome). It may also be used to monitor conditions where these antibodies are suspected.

Common Conditions Linked to Positive Results

Positive results for anti-cardiolipin antibodies can be associated with autoimmune diseases, such as systemic lupus erythematosus (SLE) or antiphospholipid syndrome (APS), which increases the risk of blood clots. However, not everyone with these antibodies will develop symptoms.

What to Expect Before the Test

No special preparation is needed for this blood test. You may have a small needle inserted into your arm to draw blood, similar to other routine blood tests. If you’re on blood thinners or have a history of bleeding issues, let your doctor know before the test.

Reference range

Titer <1:100: Negative; Titer 1:100-1:200: Borderline/Past exposure; Titer 1:200-1:800: Suggestive of past or chronic exposure; Titer ≥1:800: Suggestive of chronic Q fever (especially infective endocarditis)N/A

Specimen: serum

No special patient preparation required. Acute and convalescent serum samples (drawn 2-4 weeks apart) are recommended for accurate diagnosis of acute Q fever. For chronic Q fever, a single specimen with Phase I IgG titer is typically diagnostic.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: When This Test Matters

Short name

Anti-Cardiolipin Antibodies (IgG)

Frequently asked questions

What Are My Next Steps If My Results Are Abnormal?
If your test results show elevated anti-cardiolipin antibodies, your doctor may recommend further testing or monitoring, depending on your symptoms and medical history. They could also check for other related antibodies or evaluate your risk for blood clots or autoimmune conditions.
Do I Need to Avoid Certain Foods or Supplements Before the Test?
No special diet or supplements are required before this test. However, if you’re on blood-thinning medications (like warfarin or aspirin), inform your healthcare provider before the test to ensure safety.
Could This Test Be Related to Other Conditions?
Yes, elevated anti-cardiolipin antibodies can sometimes be linked to other autoimmune diseases (like Sjogren’s syndrome) or infections. If your doctor suspects another condition, they may order additional tests to clarify the cause.
  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