This MedLibrary.org supplementary page on Lupus anticoagulant is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
| Lupus anticoagulant Classification and external resources |
|
| ICD-9 | 289.81 |
|---|---|
| DiseasesDB | 775 |
| MeSH | D016682 |
Lupus anticoagulant (also known as lupus antibody, LA, or lupus inhibitors) is a medical phenomenon where autoantibodies bind to phospholipids and proteins associated with the cell membrane. Since interactions between the cell membrane and clotting factors are necessary for proper functioning of the coagulation cascade, the lupus anticoagulant can interfere with blood clotting as well as in-vitro tests of clotting function. Paradoxically, lupus anticoagulants are also risk factors for thrombosis.
The name "lupus anticoagulant" is a misnomer. Most patients with a lupus anticoagulant do not actually have lupus erythematosus, and only a small proportion will proceed to develop this disease (which causes joint pains, skin problems and renal failure, amongst other complications). Patients with lupus erythematosus are more likely to develop a lupus anticoagulant than the general population.
Conceptually, lupus anticoagulants overlap with the antiphospholipid antibody syndrome. Lupus anticoagulants can be understood as the tendency of antiphospholipid antibodies to prolong the clotting times, especially in phospholipid rich clotting testing such as the dilute Russell's viper venom time.
Often, the lupus anticoagulant is diagnosed on asymptomatic patients by a routine blood testing prior to surgery. Patients with a lupus anticoagulant are prone to thrombosis, excess bleeding, and habitual abortion (repeated miscarriages).
Contents |
Workup
The presence of prolonged clotting times on a routine plasma test often triggers functional testing of the blood clotting function, as well as serological testing to identify common autoantibodies such as antiphospholipid antibodies. These antibodies tend to delay in-vitro coagulation in phospholipid-dependent laboratory tests such as the partial thromboplastin time.
The initial workup of a prolonged PTT is a mixing test whereby the patient's plasma is mixed with normal pooled plasma and the clotting is re-assessed. If a clotting inhibitor such as a lupus anticoagulant is present, the inhibitor will interact with the normal pooled plasma and the clotting time will remain abnormal. However, if the clotting time of the mixed plasma corrects towards normal, the diagnosis of an inhibitor such as the lupus anticoagulant is excluded; the diagnosis is a deficient clotting factor that is replenished by the normal plasma.
If the mixing test indicates an inhibitor, diagnosis of a lupus anticoagulant is then confirmed with phospholipid-sensitive functional clotting testing, such as the dilute Russell's viper venom time, or the Kaolin clotting time. Excess phospholipid will eventually correct the prolongation of these prolonged clotting tests (conceptually known as "phospholipid neutralization" in the clinical coagulation laboratory), confirming the diagnosis of a lupus anticoagulant.
Treatment
Treatment for a lupus anticoagulant is usually undertaken in the context of documented thrombosis, such as extremity phlebitis or dural sinus vein thrombosis. Patients with a well-documented (i.e., present at least twice) lupus anticoagulant and a history of thrombosis should be considered candidates for indefinite treatment with anticoagulants. Patients with no history of thrombosis and a lupus anticoagulant should probably be observed. Current evidence suggests that the risk of recurrent thrombosis in patients with an antiphospholipid antibody is enhanced whether that antibody is measured on serological testing or functional testing. The Sapporo criteria specify that both serological and functional tests must be positive to diagnose the antiphospholipid antibody syndrome.[1].
Miscarriages may be more prevalent in patients with a lupus anticoagulant. These can be prevented with the administration of low molecular weight heparins (LMWHs), and thrombosis is treated with anticoagulants (LMWHs and warfarin).[2]
References
- ^ Viard JP, Amoura Z, Bach JF (1991). "[Anti-beta 2 glycoprotein I antibodies in systemic lupus erythematosus: a marker of thrombosis associated with a circulating anticoagulant]" (in French). C. R. Acad. Sci. III, Sci. Vie 313 (13): 607–12. PMID 1782567.
- ^ Dolitzky M, Inbal A, Segal Y, Weiss A, Brenner B, Carp H (2006). "A randomized study of thromboprophylaxis in women with unexplained consecutive recurrent miscarriages". Fertil Steril 86 (2): 362–6. doi:. PMID 16769056.
External links
- Information on lupus anticoagulant from the American Association for Clinical Chemistry
- MeSH Lupus+anticoagulant
|
||||||||
Wikipedia content modification information:
- This page was last modified on 22 September 2008, at 11:27.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Lupus anticoagulant".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.