0521779407-10 CUNY1086/Karliner 0 521 77940 7 June 7, 2007 18:40
812 Immune Hemolytic Anemia■accounts for approximately 8% of all autoimmune hemolytic ane-
mias
■idiopathic or associated with connective tissue and lymphoprolifer-
ative disorders
■DIHA
■exposure to drugs (e.g., penicillins, cephalosporins, quinidine,
phenacetin, chlorpropamide, sulfonylureas, alpha-methyldopa, and
procainamide)
■can result from one of three different mechanisms:
■hapten: drug binds to red blood cell membrane forming neoanti-
gen to which antibodies develop; direct antiglobulin (Coombs) test
(DAT) positive for IgG; extravascular hemolysis; penicillins and
cephalosporins
■immune complex: drug binds to plasma proteins eliciting antibodies
that form circulating immune complexes and activate complement;
DAT positive for complement; intravascular or extravascular
hemolysis; sulfonamides, phenothiazines, quinidine, isoniazid
■autoantibody: drug directly stimulates production of autoantibody
to antigens on red cell membrane; DAT positive for IgG; extravascular
hemolysis; alpha-methyldopa, levodopa, procainamide, mefenamic
acid
➣Drugs inducing T-cell dysregulation and increasing the likeli-
hood of disease-mediated AIHA: fludarabine in CLL, cladribine,
etc.Signs & Symptoms
■General
■fatigue, fever, tachycardia, dyspnea, angina, pallor, jaundice, CHF
(pulmonary edema, jugular venous distention, peripheral edema),
splenomegaly
■intravascular hemolysis may additionally present with hemo-
globinemia, hemoglobinuria, DIC (petechiae, purpura, bleeding,
thrombosis) and acute renal failure
■WAHA
■severity of extravascular hemolyis ranges from indolent to life threat-
ening
■mildest form: DAT is positive; no hemolysis
■symptomatic form: anemia (Hgb <8 g/dl), jaundice, splenomegaly
■severest form: fulminant hemolysis, progressive anemia, congestive
heart failure, respiratory distress, and neurologic abnormalities
■Evan’s syndrome: accompanied by immune thrombocytopenia