Antiphospholipid Syndrome (APS)
Antiphospholipid syndrome (APS) is an autoimmune condition associated with an increased risk of abnormal blood clot formation and certain pregnancy-related complications. It occurs when the immune system produces antibodies that interfere with normal blood clotting regulation.
APS can occur on its own (primary APS) or alongside another autoimmune disease, most commonly SLE (secondary APS).
At National Path Lab (NPL), laboratory testing detects specific antiphospholipid antibodies to support the evaluation of suspected APS, helping guide your doctor's assessment of clotting risk and pregnancy management.
About Antiphospholipid Syndrome (APS)
Causes & Risk Factors
APS results from the immune system producing antibodies against proteins that bind to phospholipids, which are involved in normal blood clotting regulation.
• Association with SLE or other autoimmune diseases — APS frequently occurs secondary to SLE, though it can also occur independently.
• Genetic factors — family history of autoimmune disease may increase susceptibility.
• Sex — like many autoimmune conditions, APS is more common in women, particularly of reproductive age.
• Possible triggers — certain infections have been proposed as potential triggers in susceptible individuals, though the exact mechanism is not fully understood.
Symptoms & When to Test
APS often comes to clinical attention due to an unexplained clotting event or pregnancy complication, rather than a gradual symptom pattern.
• Unexplained blood clots (deep vein thrombosis, pulmonary embolism, or stroke, particularly at a young age)
• Recurrent pregnancy loss, especially after the first trimester
• Pregnancy complications such as pre-eclampsia or placental insufficiency
• Thrombosis occurring at an unusually young age without other clear risk factors
• Livedo reticularis — a mottled, lace-like skin discoloration, in some patients
When Should You Consider Testing?
Your doctor may consider APS testing in appropriate clinical situations such as unexplained blood clots, recurrent pregnancy loss, certain pregnancy complications, thrombosis at an unusually young age, or other clinical features suggestive of APS.
Why Tests Are Combined
No single antiphospholipid antibody test is sufficient on its own — international diagnostic criteria for APS require both clinical criteria (a clotting event or pregnancy complication) and laboratory criteria (positive antibody testing, often confirmed on repeat testing).
Lupus anticoagulant, anticardiolipin antibodies, and anti-β2 glycoprotein I antibodies each detect a different aspect of antiphospholipid antibody activity; a patient may be positive for one, two, or all three, which affects both diagnosis and assessment of clotting risk.
Because antibody levels can fluctuate, and because false-positive results can occur (for example, transiently after certain infections), confirmatory repeat testing at least 12 weeks apart is often part of a complete APS evaluation, as advised by your doctor.
Tests Available at NPL
Test Code | Test | Clinical Relevance |
P0024
| LUPUS ANTICOAGULANT PANEL; LAC PANEL | One of the major laboratory investigations used in APS evaluation, assessing the clotting-related functional activity of antiphospholipid antibodies. |
I0019 I0020 | ANTI CARDIOLIPIN ANTIBODY IGG | May be tested for IgG and/or IgM antibodies depending on the clinical situation and laboratory protocol. |
I0124 I0125 | ANTI BETA 2 GLYCOPROTEIN 1; B2GP1, IGG | Another important antiphospholipid antibody used in APS evaluation, often tested alongside anticardiolipin antibodies. |
Most autoimmune antibody tests and inflammatory markers do not require fasting. However, if your doctor has ordered other tests at the same time — such as glucose or lipid testing — fasting may be required for those investigations. Please follow the preparation instructions provided by your doctor or NPL.
Medical Disclaimer Laboratory tests are supportive tools and should not be used alone to diagnose or exclude antiphospholipid syndrome. Results should be interpreted by a qualified healthcare professional together with clinical history and, where relevant, confirmatory repeat testing. |