Cardiolipin Antibodies (IgA, IgG, IgM) Biomarker Testing
It measures anticardiolipin antibodies linked to abnormal clotting and pregnancy loss, with convenient ordering and clear results through Vitals Vault/Quest.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
Cardiolipin antibodies (also called anticardiolipin antibodies) are immune proteins that can attach to phospholipids and related proteins in your body. When they are persistently elevated, they can be associated with a higher risk of abnormal blood clots and certain pregnancy complications.
This test measures three antibody types—IgA, IgG, and IgM—because different people express different patterns. Your result is not a diagnosis by itself, but it can be an important piece of an antiphospholipid syndrome (APS) evaluation when combined with your history and other labs.
If you are reviewing a positive result, the most practical next questions are usually: “Is it high enough to matter?”, “Could it be temporary?”, and “What should I test alongside it or repeat later?” This page walks you through those points in plain language.
Do I need a Cardiolipin Antibodies IgA IgG IgM test?
You are more likely to need cardiolipin antibody testing if you have had an unexplained blood clot (such as a deep vein thrombosis, pulmonary embolism, or stroke at a younger age), especially if it happened without a clear trigger. Testing may also be considered if you have a history of recurrent pregnancy loss, stillbirth, severe preeclampsia, or placental complications.
This test can also be useful if you have an autoimmune condition (including lupus) and your clinician is assessing clotting risk, or if you have a low platelet count or livedo reticularis (a lacy, purplish skin pattern) with other concerning features.
If you are acutely ill or recently had an infection, a one-time positive result can be temporary. In many cases, the most meaningful information comes from repeat testing after time has passed.
This lab supports clinician-directed care and risk assessment; it does not confirm or rule out APS on its own.
This is a blood test performed in a CLIA-certified laboratory; results should be interpreted with your symptoms, clotting history, and companion antiphospholipid tests rather than used as a standalone diagnosis.
Lab testing
Order Cardiolipin Antibodies (IgA, IgG, IgM) through Vitals Vault and complete your draw at Quest.
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this test with Vitals Vault
With Vitals Vault, you can order cardiolipin antibodies (IgA, IgG, IgM) directly and complete your blood draw through the Quest network. This is helpful when you are trying to clarify a past result, document persistence over time, or bring a complete set of labs to a clinician visit.
After your results post, you can use PocketMD to get plain-language context for what “negative,” “borderline,” or “positive” typically means, and what follow-up questions to ask based on your personal history. If your clinician recommends confirmation testing, you can also reorder the same test later to check whether the antibodies persist.
If you are building a broader clotting or autoimmune workup, Vitals Vault makes it easy to add companion labs so you are not interpreting a single marker in isolation.
- Order online and draw at Quest locations
- Clear, shareable results for your clinician
- PocketMD guidance for next-step questions and retest timing
Key benefits of Cardiolipin Antibodies (IgA, IgG, IgM) testing
- Helps evaluate whether antiphospholipid antibodies may be contributing to unexplained blood clots.
- Adds useful detail to pregnancy-loss and placental-complication evaluations when clinically appropriate.
- Separates IgG, IgM, and IgA patterns, which can matter for risk interpretation and follow-up planning.
- Supports confirmation of persistence by enabling repeat testing after the recommended interval.
- Provides context for autoimmune-related clotting risk when combined with your history and other APS labs.
- Helps your clinician decide whether additional tests (like lupus anticoagulant or anti-β2 glycoprotein I) are needed.
- Creates a baseline you can track over time, with PocketMD support to interpret results in plain language.
What is Cardiolipin Antibodies IgA IgG IgM?
Cardiolipin antibodies are autoantibodies—immune proteins that mistakenly target parts of your own cells. In this case, they react to cardiolipin, a phospholipid found in cell membranes, and often to phospholipid-binding proteins (most notably β2-glycoprotein I). When these antibodies are present at significant levels and persist over time, they can be part of the laboratory picture of antiphospholipid syndrome (APS).
The test reports three immunoglobulin classes: IgG, IgM, and IgA. IgG is the most commonly used isotype in APS classification criteria, while IgM can be relevant in some people. IgA is not part of the classic APS criteria in many guidelines, but it may still be ordered when suspicion remains high or when other markers are negative.
A key point is that a positive result can be transient. Infections, inflammation, and some medications can lead to temporary elevations, which is why repeat testing is often recommended before labeling a result as clinically meaningful.
How these antibodies relate to clotting
Antiphospholipid antibodies can interfere with normal anticoagulant pathways, activate endothelial cells and platelets, and promote inflammation. The end result can be a tendency toward clot formation in veins or arteries in susceptible people. Your individual risk depends on the antibody type, the level (titer), whether it persists, and whether other APS antibodies are also present.
Why three antibody types are reported
IgG, IgM, and IgA are different antibody classes with different clinical associations. Some people have only one isotype elevated, while others have multiple. In general, higher titers and multiple positive antiphospholipid tests tend to be more concerning than a single low-level, one-time positive.
What do my Cardiolipin Antibodies IgA IgG IgM results mean?
Low or negative cardiolipin antibodies
A low or negative result usually means these specific antibodies were not detected or are below the lab’s cutoff. This lowers the likelihood that anticardiolipin antibodies are a major contributor to clotting or pregnancy complications, but it does not rule out APS by itself. Some people with APS have other positive markers (such as lupus anticoagulant or anti-β2 glycoprotein I) even when cardiolipin antibodies are negative. If your clinical suspicion is high, your clinician may still recommend a full antiphospholipid antibody workup.
In-range results (no significant elevation)
An in-range result is typically interpreted similarly to negative, especially if all three isotypes are within the lab’s reference interval. If you are testing because of a prior positive, an in-range result can suggest the earlier finding was transient or has resolved. Your clinician may consider whether timing mattered—for example, whether the earlier test was done during an infection or shortly after a clot. When APS is a concern, persistence and pattern across multiple tests are often more important than a single snapshot.
High or positive cardiolipin antibodies
A high result means your immune system is producing measurable anticardiolipin antibodies. The clinical significance depends on the isotype (IgG, IgM, and/or IgA), the level (many labs report low/medium/high positive categories), and whether the elevation persists on repeat testing at least 12 weeks apart. A single low-positive result can occur temporarily, while a persistent moderate-to-high positive—especially alongside other positive antiphospholipid tests—can be more consistent with APS. If you have had a clot or pregnancy complications, a positive result is a strong reason to review next steps with your clinician.
Factors that influence cardiolipin antibody results
Recent infections and inflammatory states can cause temporary elevations, so timing matters. Testing soon after a clot, surgery, or hospitalization can also complicate interpretation because your immune system may be activated. Different laboratories and assay platforms can use different units and cutoffs, so it is best to compare results from the same lab when trending. Finally, the overall APS risk picture changes when other tests are positive (lupus anticoagulant and anti-β2 glycoprotein I), so your clinician may interpret your result as part of a panel rather than in isolation.
What’s included
- Cardiolipin Ab (Iga)
- Cardiolipin Ab (Igg)
- Cardiolipin Ab (Igm)
Frequently Asked Questions
Do I need to fast for a cardiolipin antibodies blood test?
Fasting is usually not required for cardiolipin antibody testing. If you are combining it with other labs (like lipids or glucose), follow the fasting instructions for the full set of tests you ordered.
What is the difference between cardiolipin antibodies and lupus anticoagulant?
They are different antiphospholipid tests. Cardiolipin antibodies are measured as IgG/IgM/IgA antibody levels, while lupus anticoagulant is a functional clotting assay that looks at how your blood behaves in the lab. Many clinicians order both because APS evaluation typically considers multiple markers.
If my cardiolipin antibodies are positive, does that mean I have antiphospholipid syndrome (APS)?
Not necessarily. APS is diagnosed using a combination of clinical criteria (such as thrombosis or specific pregnancy complications) and persistent laboratory positivity. A one-time positive result—especially if low—can be transient, which is why repeat testing after at least 12 weeks is commonly recommended.
When should cardiolipin antibodies be retested?
If the goal is to confirm persistence for APS evaluation, retesting is often done at least 12 weeks after the first positive. Your clinician may adjust timing based on recent infection, pregnancy status, or whether you are in the middle of an acute event.
Can infections cause a false positive cardiolipin antibody result?
Yes, temporary elevations can occur with infections and other inflammatory conditions. That does not mean the result is “wrong,” but it may not reflect a persistent autoimmune pattern. Repeat testing after recovery helps clarify whether the antibodies persist.
Which cardiolipin antibody is most important: IgG, IgM, or IgA?
IgG is most commonly emphasized in many APS criteria and risk discussions, but IgM can also be relevant, and IgA may add context in selected situations. The most useful interpretation usually considers the isotype, the titer (how high it is), whether it persists, and whether other antiphospholipid tests are also positive.
What other tests are commonly ordered with cardiolipin antibodies?
Common companion tests include lupus anticoagulant testing and anti-β2 glycoprotein I antibodies (IgG/IgM, and sometimes IgA). Depending on your situation, your clinician may also evaluate platelet count, kidney function, and other clotting or autoimmune markers.