Thrombocytopenia.

Decreased platelet count.

Is characterized by spontaneous bleeding which is evident at platelet count below 20,000/μL, 20,000 to 50,000 may lead to post-traumatic bleeding.

a prolonged bleeding time

normal PT and PTT.

Sites of bleeding in thrombocytopenia – following are common sites but bleeding can occur from any site though.

Skin and mucous membranes

Petechie

Ecchymosis

Hemorrhagic vesicles

Gingival bleeding and epistaxis

Menorrhagia

Gastrointestinal bleeding

Intracranial bleeding

Spontaneous bleeding after trauma

Thrombocytopenia is one of the most common hematological manifestations of AIDS.

Causes of Thrombocytopenia:

Decreased production of platelets

Generalized diseases of bone marrow

Aplastic anemia: congenital and acquired

Marrow infiltration: leukemia, disseminated cancer

Selective impairment of platelet production

Drug-induced: alcohol, thiazides, cytotoxic drugs

Infections: measles, human immunodeficiency virus (HIV)

Ineffective megakaryopoiesis

Megaloblastic anemia

Myelodysplastic syndromes

Decreased platelet survival

Immunologic destruction:

Autoimmune: idiopathic thrombocytopenic purpura, systemic lupus erythematosus

Isoimmune: post-transfusion and neonatal

Drug-associated: quinidine, heparin, sulfa compounds

Infections: infectious mononucleosis, HIV infection, cytomegalovirus

Nonimmunologic destruction:

Disseminated intravascular coagulation

Thrombotic thrombocytopenic purpura

Giant hemangiomas

Microangiopathic hemolytic anemias

Sequestration: Hypersplenism

Dilutional.