Cases and Updates
December 2010
Specialized Hemostasis & Thrombosis Laboratory
and Coagulation Consultation Update
Antiphospholipid Syndrome
Kristopher Kersch, MD, Pathology Resident, PGY4
Oxana Tcherniantchouk, MD, Director Coagulation Consultation Service
Antiphospholipid (APL) antibodies are a heterogeneous group of antibodies directed against proteins bound to phospholipids. The antiphospholipid syndrome which occurs in up to 60% individuals with APL antibodies is the most common cause of acquired thrombophilia, and has been implicated in 30% of strokes under the age of 50 and 20% of myocardial infarctions under the age of 45. Even over time, not all patients with measurable antiphospholipid antibody develop the syndrome which is defined by the presence of 1) at least one type of antiphospholipid antibody such as a lupus anticoagulant (LA) or high titer anti-cardiolipin or an anti-beta 2-GPI; and 2) one of several possible clinical manifestations, the most common of which are venous and/or arterial thromboses or recurrent fetal loss. Diagnosis of the antiphospholipid syndrome alerts the physicians and patients to the possibility of developing additional potentially significant clinical manifestations, and may indicate a need for long-term anticoagulation.
As mentioned above, there exists an approximately 60% concordance between having a positive antiphospholipid antibody assay and the presence of the antiphospholipid syndrome. Cedars-Sinai offers the Antiphospholipid Antibody Profile (APHO) for the detection of antiphospholipid antibodies when the APL syndrome is suspected. This APHO panel consists of:
• PT and aPTT
• detection of both IGM and IgG antibody directed towards beta-2 GPI
• anti-cardiolipin, both IgM and IgG
• clot-based lupus-anticoagulant (LA) assays, which include a hexagonal phospholipid assay and a dilute Russell viper venom test.
An interpretive coagulation consultation is intrinsic to our report. Patients without an antiphospholipid syndrome can produce transient APL antibodies, particularly in the setting of infection, cancer, or pregnancy. For this reason, positive tests without concomitant clinical sequelae should be repeated in 12 weeks. When the syndrome itself produces a consistently elevated aPTT, we recommend that an anti-Factor Xa assay (also available from the Cedars-Sinai laboratory) be performed to appropriately dose heparin-based anticoagulation.
It It is important to recognize that antiphospholipid antibodies can interact with certain other laboratory tests. Of particular note is the fact that cardiolipin is the target antigen used in the RPR and VDRL syphilis screening tests. False-positive syphilis test results can occur in patients with anti-cardiolipin antibodies, and vise versa. Additionally it is important to consider that warfarin, heparin, and direct thrombin inhibitors (DTIs) such as argatroban, lepirudin, and bivalirudin, can affect clot-based antiphospholipid antibody assays such as PT, aPTT, Russell viper venom time, and the LA by hexagonal phospholipid assay. All these interactions are considered in our consultation. For patients with a clinical history of recurrent fetal loss, if the antiphospholipid panel is negative we recommend consideration of an additional assay for anti-Annexin antibodies which are rarer antiphospholipid antibodies that have been implicated in placental thrombosis.
Inpatient orders are placed in CS-Link as:
Coag Consult: Antiphospholipid Panel
Heparin, Unfractionated (Xa Inhibition)
For outpatient orders use CSMC requisition form:
Antiphospholipid Antibody Profile (APHO)
Unfractionated Heparin
For any additional information contact
Oxana Tcherniantchouk, M.D.
(310) 423 -5471
Oxana.Tcherniantchouk@cshs.org
Kristopher Kersch, MD Oxana Tcherniantchouk, MD
