Decreased platelet production

Bone marrow failure (e.g., aplastic anemia, paroxysmal nocturnal hemoglobinuria, Shwachman-Diamond syndrome)

Bone marrow suppression (e.g., from medication, chemotherapy, or irradiation)

Chronic alcohol abuse*

Congenital macrothrombocytopenias (e.g., Alport syndrome, Bernard-Soulier syndrome, Fanconi anemia, platelet-type or pseudo–von Willebrand disease, Wiskott-Aldrich syndrome)

Infection† (e.g., cytomegalovirus, Epstein-Barr virus, hepatitis C virus, HIV, mumps, parvovirus B19, rickettsia, rubella, varicella-zoster virus)

Myelodysplastic syndrome

Neoplastic marrow infiltration

Nutritional deficiencies (vitamin B12 and folate)

Increased platelet consumption

Alloimmune destruction (e.g., posttransfusion, neonatal, posttransplantation)

Autoimmune syndromes (e.g., antiphospholipid syndrome, systemic lupus erythematosus, sarcoidosis)

Disseminated intravascular coagulation*/severe sepsis*

Drug-induced thrombocytopenia

Heparin-induced thrombocytopenia

Immune thrombocytopenic purpura*

Infection † (e.g., cytomegalovirus, Epstein-Barr virus, hepatitis C virus, HIV, mumps, parvovirus B19, rickettsia, rubella, varicella-zoster virus)

Mechanical destruction (e.g., aortic valve, mechanical valve, extracorporeal bypass)

Preeclampsia/HELLP syndrome

Thrombotic thrombocytopenic purpura/hemolytic uremic syndrome

Sequestration/other

Chronic alcohol abuse*

Dilutional thrombocytopenia (e.g., hemorrhage, excessive crystalloid infusion)

Gestational thrombocytopenia

Hypersplenism (e.g., distributional thrombocytopenia)

Liver disease (e.g., cirrhosis, fibrosis, portal hypertension)

Pseudothrombocytopenia

Pulmonary emboli

Pulmonary hypertension