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| '''For patient information click [[Autoimmune hemolytic anemia (patient information)|here]]'''
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| {{Infobox_Disease | | | {{Infobox_Disease | |
| Name = Autoimmune hemolytic anemia | | | Name = Autoimmune hemolytic anemia | |
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| MeshID = D000744 | | | MeshID = D000744 | |
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| {{SI}} | | {{Autoimmune hemolytic anemia}} |
| {{CMG}}
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| ==Overview==
| | '''For patient information click [[Autoimmune hemolytic anemia (patient information)|here]]''' |
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| '''Autoimmune hemolytic anemia''' (AIHA) is a type of [[hemolytic anemia]] where the body's immune system attacks its own [[red blood cells]] (RBCs), leading to their destruction ([[hemolysis]]). [[Antibodies]] and associated [[complement system]] components become fixed onto the [[Red blood cell|RBC]] surface. These [[antibodies]] can be detected with the [[Coombs test#Direct Coombs test|direct antiglobulin test]], also known as the direct [[Coombs test]]. AIHA can also be induced by several drugs including methyl-dopa and fluarabine. | | {{CMG}} '''Assosciate Editor(s)-In-Chief:''' [[User: Prashanthsaddala|Prashanth Saddala M.B.B.S]]; {{shyam}}, [[User:Irfan Dotani|Irfan Dotani]] [3] |
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| [[Autoimmunity]] must not be confused with [[alloimmunity]].
| | {{SK}} AIHA; hemolytic anemia with autoimmune cause. |
| ==Historical perspective== | | ==[[Autoimmune hemolytic anemia overview|Overview]]== |
| "Blood-induced icterus" produced by the release of massive amounts of a coloring material from blood cells followed by the formation of bile was recognized and described by Vanlair and Masius' in 1871. About 20 years later, Hayem distinguished between congenital hemolytic anemia and an acquired type of infectious icterus associated with chronic splenomegaly. In 1904, Donath and Landsteiner suggested a serum factor was responsible for hemolysis in paroxysmal cold hemoglobinuria. French investigators led by Chauffard stressed the importance of red-cell [[autoagglutination]] in patients with acquired hemolytic anemia. In 1930, Lederer and Brill described cases of acute [[hemolysis]] with rapid onset of anemia and rapid recovery after transfusion therapy. These hemolytic episodes were thought to be due to infectious agents. A clear distinction between congenital and acquired hemolytic anemia was not drawn, however, until Dameshek and Schwartz in 1938, and in 1940, they demonstrated the presence of abnormal hemolysins in the sera of patients with acquired [[hemolytic anemia]] and postulated an [[immunology|immune mechanism]].<br />
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| During the past three decades, studies defining red-cell blood groups and serum antibodies have produced diagnostic methods that have laid the basis for immunologic concepts relevant to many of the acquired hemolytic states. Of these developments, the antiglobulin test described by Coombs, Mourant, and Race in 1945 has proved to be one of the more important, useful tools now available for the detection of immune hemolytic states. This technique demonstrated that a rabbit antibody against human globulin would induce agglutination of human red cells "coated with an incomplete variety of rhesus antibody". C. Moreschlit had used the same method in 1908 in a goat antirabbit-red-cell system. The test was historically premature and was forgotten. In 1946, Boorman, Dodd, and Loutit applied the direct antiglobulin test to a variety of hemolytic anemias, and laid the foundation for the clear distinction of autoimmune from congenital hemolytic anemia.<br />
| | ==[[Autoimmune hemolytic anemia historical perspective|Historical Perspective]]== |
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| ==Classification== | | ==[[Autoimmune hemolytic anemia classification|Classification]]== |
| Haemolysis can be intravascular or extravascular.
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| '''Intravascular haemolysis'''<br>
| | ==[[Autoimmune hemolytic anemia pathophysiology|Pathophysiology]]== |
| Red blood cell lysis occurs in the circulation as a result of activation of the [[complement system]] cascade.
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| '''Extravascular haemolysis'''<br>
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| Red Blood Cells that are coated with antibodies are specifically recognised in the [[reticuloendothelial system]] and destroyed by [[macrophages]].
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| ===Subtypes=== | | ==[[Autoimmune hemolytic anemia causes|Causes]]== |
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| *'''[[Warm antibody autoimmune hemolytic anemia]]'''
| | ==[[Autoimmune hemolytic anemia differential diagnosis|Differentiating Autoimmune hemolytic anemia from other Diseases]]== |
| :*Idiopathic
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| :*[[Systemic lupus erythematosus]]
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| :*[[Evans' syndrome]] (antiplatelet antibodies and haemolytic antibodies)
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| :*[[Chronic lymphocytic leukemia]]
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| :*Drugs ([[methyldopa]])
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| *'''Cold antibody autoimmune hemolytic anemia'''
| | ==[[Autoimmune hemolytic anemia epidemiology and demographics|Epidemiology and Demographics]]== |
| :*[[Idiopathic cold hemagglutinin syndrome]]
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| :*[[Infectious mononucleosis]]
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| :*[[Paroxysmal cold hemoglobinuria]] (rare)
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| :*[[Lymphoma]]
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| *'''Mixed-type autoimmune hemolytic anemia'''
| | ==[[Autoimmune hemolytic anemia risk factors|Risk Factors]]== |
| ==Causes==
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| The causes of AIHA are poorly understood. The disease may be primary, or secondary to another underlying illness. The primary illness is [[idiopathic]] (the two terms being used synonymously). Idiopathic AIHA accounts for approximately 50% of cases.<ref>{{cite journal |author=Gupta S, Szerszen A, Nakhl F, ''et al.'' |title=Severe refractory autoimmune hemolytic anemia with both warm and cold autoantibodies that responded completely to a single cycle of rituximab: a case report |journal=J Med Case Reports |volume=5 |pages=156 |year=2011 |pmid=21504611 |pmc=3096571 |doi=10.1186/1752-1947-5-156 |url=http://www.jmedicalcasereports.com/content/5//156}}</ref> Secondary AIHA can result from many other illnesses. Warm and cold type AIHA each have their own more common secondary causes. The most common causes of secondary warm-type AIHA include lymphoproliferative disorders (e.g. [[chronic lymphocytic leukemia]], [[lymphoma]]) and other autoimmune disorders (e.g. [[systemic lupus erythematosis]], [[rheumatoid arthritis]], [[scleroderma]], [[ulcerative colitis]]). Less common causes of warm-type AIHA include neoplasms other than lymphoid, and infection. Secondary cold type AIHA is also primarily caused by lymphoproliferative disorders, but is also commonly caused by infection, especially by mycoplasma, viral pneumonia, infectious mononucleosis and other respiratory infections. Less commonly, it can be caused by concomitant autoimmune disorders.<ref name=Sokol81/>
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| Drug-induced AIHA, though rare, can be caused by a number of drugs, including [[methyldopa|α-methyldopa]] and [[penicillin]]. This is a [[type II hypersensitivity|type II immune response]] in which the drug binds to [[macromolecule|macromolecules]] on the surface of the RBCs and acts as an antigen. Antibodies are produced against the RBCs, which leads to complement activation. Complement fragments, such as C3a, C4a and C5a, activate granular leukocytes (e.g. neutrophils), while other components of the system (C6, C7, C8, C9) can either form the membrane attack complex (MAC) or can bind the antibody, aiding phagocytosis by [[macrophage|macrophages]] (C3b). This is one type of "penicillin allergy".
| | ==[[Autoimmune hemolytic anemia screening|Screening]]== |
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| | ==[[Autoimmune hemolytic anemia natural history, complications and prognosis|Natural History, Complications and Prognosis]]== |
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| | ==Diagnosis== |
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| | [[Autoimmune hemolytic anemia diagnostic study of choice|Diagnostic Study of Choice]] | [[Autoimmune hemolytic anemia history and symptoms|History and Symptoms ]] | [[Autoimmune hemolytic anemia physical examination|Physical Examination]] | [[Autoimmune hemolytic anemia laboratory findings|Laboratory Findings]] | [[Autoimmune hemolytic anemia electrocardiogram|Electrocardiogram]] | [[Autoimmune hemolytic anemia chest x-ray|X-ray]] | [[Autoimmune hemolytic anemia echocardiography and ultrasound|Echocardiography and Ultrasound]] | [[Autoimmune hemolytic anemia CT|CT]] | [[Autoimmune hemolytic anemia MRI|MRI]] | [[Autoimmune hemolytic anemia other imaging findings|Other Imaging Findings]] | [[Autoimmune hemolytic anemia other diagnostic studies|Other Diagnostic Studies]] |
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| ==Laboratory findings==
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| *Positive direct [[Coombs test]]
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| *[[Anaemia]]
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| ==Treatment== | | ==Treatment== |
| Much literature exists regarding the treatment of AIHA. Efficacy of treatment depends on the correct diagnosis of either warm or cold type AIHA.
| | [[Autoimmune hemolytic anemia medical therapy|Medical Therapy]] | [[Autoimmune hemolytic anemia surgery |Surgery]] | [[Autoimmune hemolytic anemia primary prevention|Primary Prevention]] | [[Autoimmune hemolytic anemia secondary prevention|Secondary Prevention]] | [[Autoimmune hemolytic anemia cost-effectiveness of therapy|Cost-Effectiveness of Therapy]] | [[Autoimmune hemolytic anemia future or investigational therapies|Future or Investigational Therapies]] |
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| Warm type AIHA is usually a more insidious disease, not treatable by simply removing the underlying cause. First line therapy for this is usually with [[corticosteroid|corticosteroids]], such as [[prednisolone]]. Following this, other immunosuppressants are considered, such as [[rituximab]], [[danazol]], [[cyclophosphamide]], [[azathioprine]] or [[cyclosporine]].
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| Cold agglutinin disease is treated by avoiding the cold or sometimes with rituximab. Removal of the underlying cause is also important.
| | ==Case Studies== |
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| Paroxysmal cold hematuria is treated by removing the underlying cause, such as infection.
| | [[Autoimmune hemolytic anemia case study one|Case #1]] |
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| ==Related chapters== | | ==Related Chapters== |
| *[[Haematology]] | | *[[Haematology]] |
| *[[Haemolytic anaemia]] | | *[[Haemolytic anaemia]] |
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| | {{WH}} |
| | {{WS}} |
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| {{Hematology}} | | {{Hematology}} |
| {{SIB}}
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| [[de:Autoimmunhämolytische Anämie]] | | [[de:Autoimmunhämolytische Anämie]] |
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| {{WikiDoc Sources}} | | {{WikiDoc Sources}} |
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| [[Category:Mature chapter]]
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| [[Category:Disease]] | | [[Category:Disease]] |
| [[Category:Autoimmune diseases]]
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| [[Category:Coagulation system]]
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| [[Category:Blood disorders]]
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| [[Category:Hematology]] | | [[Category:Hematology]] |