Clinical clues	Possible etiology
Acute illness/hospitalization*
Anemia, neurologic abnormalities (aphasia, hemiplegia, mental status changes, seizures, paresthesia, visual disturbance, renal dysfunction)	Thrombotic thrombocytopenic purpura (rare)
Blood transfusion reaction, infection, malignancy, pancreatitis, pregnancy (preeclampsia, acute postpartum hemorrhage, septic abortion)	Disseminated intravascular coagulation (rare)
Infection
Infectious diarrhea in children (Escherichia coli O157:H7), renal dysfunction	Hemolytic uremic syndrome
Upper respiratory tract infection, arthralgias, gastrointestinal symptoms (typically in children)	Henoch-Schönlein purpura
Inherited/autoimmune syndromes
Epistaxis, gingival bleeding, and menorrhagia, often with lifelong bleeding but negative laboratory test results (prothrombin time, partial thromboplastin time)	von Willebrand disease
Hypermobile joints with dislocations, hyperextensibility of skin	Ehlers-Danlos syndrome (collagen disorder), other connective tissue disease
Joint/soft tissue bleeding in men	Hemophilia A (factor VIII) or B (factor IX), other factor deficiency
Malar rash, arthralgias, family history of autoimmune disorders	Systemic lupus erythematosus
Telangiectasias (lips, tongue, nasal cavity, skin, gastrointestinal tract), epistaxis	Hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu syndrome)
Viral infection; may be asymptomatic or show signs of mucocutaneous bleeding if platelet count is low	Idiopathic thrombocytopenic purpura (immune thrombocytopenic purpura)
Malignancy
Lymphadenopathy, renal failure, splenomegaly	Hematologic malignancy
Nutrition
Alcohol use, ascites, gynecomastia, scleral icterus, spider angioma, splenomegaly	Alcoholic liver disease
Poor nutritional intake (fruits and vegetables)	Vitamin C deficiency (scurvy), vitamin K deficiency
Physiologic/external forces
Bruising on upper thighs and arms (often in women)	Purpura simplex (easy bruising)
Report of injury or atypical pattern of bruising inconsistent with history; bruising in children who are not mobile; bruises in the pattern of objects	Physical abuse
Thin skin with dark ecchymosis, often in older adults (most typically over extensor surfaces of arms)	Senile purpura
Pregnancy-related
Preeclampsia	Hemolysis, elevated liver enzyme levels, low platelet count syndrome