Anti-Cardiolipin Antibody (IgG) - Immunoassay (Serum)
This test measures the presence of antibodies in your blood that target cardiolipin, a fatty substance found in cell membranes. These antibodies may be linked to certain autoimmune conditions.
["This test helps assess potential autoimmune or inflammatory conditions."]
Key facts at a glance
- LOINC
- 42897-9
- Short code
- COXPH1M
- Synonyms
- C burnet Ph1 IgM Ser IF-aCnc
- Category
- chemistry
- Sample
- serum
- Container
- Serum separator tube (SST), red-top tube, or tiger-top tube
- Units
- N/A
- Ref low
- 0
- Ref high
- 1
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- ≥ 0 years
- Method
- Immunofluorescence (IFA)
- CPT
- 86638
- SNOMED
- 122450004
- Specimen volume
- 1–2 mL of serum (minimum 0.5 mL)
- Stability
- Stable for 7 days at 2–8°C; for prolonged storage, freeze at -20°C or below. Avoid repeated freeze-thaw cycles.
- Hemolysis max
- 100
- Lipemia max
- 100
- Icterus max
- 50
- TAT
- 24–72 hours
- Order
- routine
What This Test Measures
The test detects IgG antibodies against cardiolipin, a phospholipid found in cell membranes. These antibodies can be part of an autoimmune response and are sometimes associated with conditions like lupus or other connective tissue disorders.
Why It’s Ordered
Your healthcare provider may order this test if you have symptoms or risk factors for autoimmune diseases, such as unexplained joint pain, rash, or other signs of inflammation. It can also be part of a broader evaluation for conditions like antiphospholipid syndrome.
What to Expect Before the Test
No special preparation is needed. You’ll have a small needle inserted into your arm to draw blood. If you’re on blood thinners, let your provider know before the test.
What to Expect During the Test
The blood sample will be collected in a tube and sent to a lab for analysis using an immunoassay method. Results are typically available within a few days.
Reference range
Negative: <1:16; Equivocal: 1:16–1:32; Positive: ≥1:64 (titers vary by laboratory). Phase 1 IgM antibodies appear in early Q fever infection and indicate acute or recent infection.N/A
No fasting required. Patient should be informed that this test detects antibodies to Coxiella burnetii, the causative agent of Q fever. Acute and convalescent samples (2–4 weeks apart) are recommended for accurate diagnosis.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated levels of anti-cardiolipin antibodies may indicate an autoimmune response or increased risk of blood clots. While not all positive results mean a definite diagnosis, they can guide further testing or monitoring for conditions like lupus, rheumatoid arthritis, or antiphospholipid syndrome. Always discuss results with your healthcare provider.
Short name
IgG Anti-Cardiolipin Antibody
Frequently asked questions
What does a positive result mean?
Can this test be used to diagnose lupus?
Do I need to fast before this test?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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