Lupus anticoagulant

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Lupus anticoagulant (LA) are heterogenous antibodies against phospholipids. The name is a misnomer on two counts, firstly, because not all patients with LA have lupus and, secondly, although LA is anticoagulant in vitro, clinically it is associated with thrombosis rather than bleeding. See antiphospholipid syndrome.

Can be detected incidentally when on a routine clotting screen the APPT (or other clotting test that is phospholipid dependent) is prolonged unexpectedly. If the test does not correct by the addition of pooled plasma, then an anticoagulant must be present (the differential diagnosis being a factor deficiency). If the test corrects with addition of phospholipid, then lupus anticoagulant is the most likely cause.

It is often asymptomatic and may be transient, hence re-testing several weeks after a positive result is recommended. It is not always by any means associated with increased risk of thrombosis.[1][2]

On the other hand, it may be detected after recurrent miscarriage or a thrombotic event, and is associated with antiphospholipid antibodies and the antiphospholipid syndrome. Patients presenting with idiopathic thrombocytopenic purpura or livedo reticularis have about a 40% chance of having it. Tests for associated antiphospholipid antibodies are usually done in symptomatic patients.

APTT is not a specific test for lupus anticoagulant, so other tests are usually done: the kaolin clotting time is specific but not very sensitive, whereas the dilute Russell's viper venom time (dRVVT) is both sensitive and specific. More details on the testing is set out in British and international guidance.[3][4][5][6]

References

  1. Moore GW, Rangarajan S, Savidge GF. The Activated Seven Lupus Anticoagulant Assay Detects Clinically Significant Antibodies. 2007 Sep 25.(Epub ahead of print) (Link to article – subscription may be required.)
  2. Galli M, Dlott J, Norbis F, Ruggeri L, Cler L, Triplett DA, Barbui T. Lupus anticoagulants and thrombosis: clinical association of different coagulation and immunologic tests. Thrombosis and haemostasis. 2000 Dec; 84(6):1012-6.
  3. Guidelines on testing for the lupus anticoagulant. Lupus Anticoagulant Working Party on behalf of the BCSH Haemostasis and Thrombosis Task Force. Journal of clinical pathology. 1991 Nov; 44(11):885-9.
  4. Brandt JT, Triplett DA, Alving B, Scharrer I. Criteria for the diagnosis of lupus anticoagulants: an update. On behalf of the Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibody of the Scientific and Standardisation Committee of the ISTH. Thrombosis and haemostasis. 1995 Oct; 74(4):1185-90.
  5. Sakakura M, Wada H, Watanabe R, Mamamuro M, Okugawa Y, Nakasaki T, Nakase T, Wakita Y, Minamikawa K, Mori Y, Nshikawa M, Shiku H. Coagulation tests and anti-phospholipid antibodies in patients positive for lupus anticoagulant. Clinical and applied thrombosis/hemostasis : official journal of the International Academy of Clinical and Applied Thrombosis/Hemostasis. 2000 Jul; 6(3):144-50.
  6. Pengo V, Tripodi A, Reber G, Rand JH, Ortel TL, Galli M, De Groot PG. Update of the guidelines for lupus anticoagulant detection. Subcommittee on Lupus Anticoagulant/Antiphospholipid Antibody of the Scientific and Standardisation Committee of the International Society on Thrombosis and Haemostasis. Journal of thrombosis and haemostasis : JTH. 2009 Oct; 7(10):1737-40.(Link to article – subscription may be required.)
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