Classification of Thrombocytopenia

Diminished or absent megakaryocytes in bone marrow

Aplastic anemia

Leukemia

Paroxysmal nocturnal hemoglobinuria (some patients)

Diminished platelet production despite the presence of megakaryocytes in bone marrow

Alcohol-induced thrombocytopenia

HIV-associated thrombocytopenia

Myelodysplastic syndromes (some)

Vitamin B12 deficiency or

Platelet sequestration in enlarged spleen

Cirrhosis with congestive splenomegaly

Gaucher disease

Primary myelofibrosis

Sarcoidosis

Immunologic destruction

Antiphospholipid syndrome

Systemic rheumatic diseases

Drug-induced thrombocytopenia

Hepatitis B-associated thrombocytopenia (uncommon)

Hepatitis C-associated thrombocytopenia

HIV-associated thrombocytopenia

Immune thrombocytopenia

Lymphoproliferative disorders (eg, chronic lymphocytic leukemia)

Neonatal alloimmune thrombocytopenia

Posttransfusion purpura

Sarcoidosis

Nonimmunologic destruction

Certain systemic infections (eg, hepatitis [any], infectious mononucleosis, cytomegalovirus infection, or dengue)

Disseminated intravascular coagulation

Hemolytic-uremic syndrome

Sepsis

Thrombocytopenia in acute respiratory distress syndrome

Thrombotic thrombocytopenic purpura

Dilution

Massive red blood cell replacement or exchange transfusion (most RBC transfusions use stored RBCs that do not contain many viable platelets)

Unknown cause

Pregnancy (eg, gestational thrombocytopenia, HELLP syndrome [hemolysis, elevated liver enzymes, and low platelets])* †