67 THROMBOCYTOPENIA General Discussion Thrombocytopenia is defined as a platelet count below the normal range for the population, which is between 150 000 and 450 000/μL. Healthy women may experience mild to moderate thrombocytopenia in the range of 75 000–150 000/μL during pregnancy and do not require any investigation. The diagnostic evaluation of thrombocytopenia begins by excluding artifactual or pseudothrombocytopenia as the etiology. This is caused by platelet clumping when EDTA is used as an anticoagulant in the blood sample. The presence of platelet clumps on examination of the peripheral smear and a normal repeat platelet count using citrated blood confirms pseudothrombocytopenia as the cause. After pseudothrombocytopenia has been excluded, the possibility of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) should be considered. A peripheral blood smear with schistocytes, increased serum levels of lactate dehydrogenase (LDH), and decreased serum haptoglobin suggest TTP/HUS or disseminated intravascular coagulation (DIC). Coagulation studies are usually normal in TTP/HUS but are prolonged in DIC. Once TTP/HUS and DIC have been excluded, drug-related thrombocytopenia and hypersplenism should be considered as possible causes. If heparin-induced thrombocytopenia is considered, the diagnosis may be confirmed by in vitro testing to detect heparin-dependent platelet antibodies. Idiopathic thrombocytopenic purpura (ITP) is a diagnosis of exclusion. Other causes of immune-mediated thrombocytopenia should be considered. These include connective tissue disease, lymphoproliferative disorders, and HIV infection. Medications Associated with Thrombocytopenia Abciximab Acetaminophen Aminoglutethimide Aminosalicylic acid Amiodarone Amphotericin B Ampicillin Amrinone Captopril Carbamazepine Chlorothiazide Chlorpromazine Chlorpropamide Cimetidine Cisplatin Clopidogrel Cyclosporine A Danazol Deferoxamine Diatrizoate meglumine Diazepam Diazoxide Diclofenac Diethylstilbestrol Digoxin Eptifibatide Furosemide Gold Haloperidol Heparin Hydrochlorothiazide Ibuprofen Interferon alpha Isoniazid Levamisole Lithium Meclofenamate Methicillin Methyldopa Minoxidil Mitomycin A Nalidixic acid Naphazoline Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: ARTHRITIS AND ARTHRALGIA HAIR LOSS HYPOTHYROIDISM TRANSAMINASE ELEVATION Stay updated, free articles. Join our Telegram channel Join Tags: Instant Work-ups A Clinical Guide to Medicine Aug 17, 2016 | Posted by admin in PEDIATRICS | Comments Off on THROMBOCYTOPENIA Full access? Get Clinical Tree
67 THROMBOCYTOPENIA General Discussion Thrombocytopenia is defined as a platelet count below the normal range for the population, which is between 150 000 and 450 000/μL. Healthy women may experience mild to moderate thrombocytopenia in the range of 75 000–150 000/μL during pregnancy and do not require any investigation. The diagnostic evaluation of thrombocytopenia begins by excluding artifactual or pseudothrombocytopenia as the etiology. This is caused by platelet clumping when EDTA is used as an anticoagulant in the blood sample. The presence of platelet clumps on examination of the peripheral smear and a normal repeat platelet count using citrated blood confirms pseudothrombocytopenia as the cause. After pseudothrombocytopenia has been excluded, the possibility of thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS) should be considered. A peripheral blood smear with schistocytes, increased serum levels of lactate dehydrogenase (LDH), and decreased serum haptoglobin suggest TTP/HUS or disseminated intravascular coagulation (DIC). Coagulation studies are usually normal in TTP/HUS but are prolonged in DIC. Once TTP/HUS and DIC have been excluded, drug-related thrombocytopenia and hypersplenism should be considered as possible causes. If heparin-induced thrombocytopenia is considered, the diagnosis may be confirmed by in vitro testing to detect heparin-dependent platelet antibodies. Idiopathic thrombocytopenic purpura (ITP) is a diagnosis of exclusion. Other causes of immune-mediated thrombocytopenia should be considered. These include connective tissue disease, lymphoproliferative disorders, and HIV infection. Medications Associated with Thrombocytopenia Abciximab Acetaminophen Aminoglutethimide Aminosalicylic acid Amiodarone Amphotericin B Ampicillin Amrinone Captopril Carbamazepine Chlorothiazide Chlorpromazine Chlorpropamide Cimetidine Cisplatin Clopidogrel Cyclosporine A Danazol Deferoxamine Diatrizoate meglumine Diazepam Diazoxide Diclofenac Diethylstilbestrol Digoxin Eptifibatide Furosemide Gold Haloperidol Heparin Hydrochlorothiazide Ibuprofen Interferon alpha Isoniazid Levamisole Lithium Meclofenamate Methicillin Methyldopa Minoxidil Mitomycin A Nalidixic acid Naphazoline Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: ARTHRITIS AND ARTHRALGIA HAIR LOSS HYPOTHYROIDISM TRANSAMINASE ELEVATION Stay updated, free articles. Join our Telegram channel Join Tags: Instant Work-ups A Clinical Guide to Medicine Aug 17, 2016 | Posted by admin in PEDIATRICS | Comments Off on THROMBOCYTOPENIA Full access? Get Clinical Tree
