Gastroenteritis
Appendicitis
Colitis
Intussusception
IBD
Perforation
SLE
Poststreptococcal glomerulonephritis<unk> 
Henoch-Schonlein purpura
IgA nephropathy
Lupus nephritis
Alport syndrome
Goodpasture syndrome
Paraneoplastic
Disseminated Intravascular Coagulation (DIC)
Thrombotic Thrombocytopenic Purpura (TTP)<unk>  <unk> 
HELLP syndrome
Heparin-Induced Thrombocytopenia (HIT)
Hereditary spherocytosis
Paroxysmal nocturnal hemoglobinuria (PNH)
Malignant hypertension
Scleroderma
Antiphospholipid Syndrome (APS)
Other medical causes: malignancy, renal allograft rejection, vasculitides like polyarteritis nodosa and Wegener's granulomatosis
Drugs: chemotherapy; Clopidogrel (Plavix) associated with TTP
Nonvascular causes: prosthetic valve (more common with mechanical, more common at aortic valve), LVAD, TIPS, coil embolization, patched AV shunt, AVM
Marrow infiltration (tumor or infection)
Viral infections (rubella, HIV)
Marrow suppression (commonly chemotherapy or radiation)
Congenital thrombocytopenia
Fanconi anemia
Alport syndrome
Bernand Soulier
Vitamin B12 and/or folate deficiency
Fanconi anemia
Alport syndrome
Bernand Soulier
Idiopathic thrombocytopenic purpura
Thrombotic Thrombocytopenic Purpura (TTP)<unk>  <unk> 
Disseminated Intravascular Coagulation (DIC)
Viral infections (HIV, mumps, varicella, EBV)
Drugs (heparin, protamine)
Postransfusion or Posttransplantation
Autoimmune destruction (SLE or Sarcoidosis)
Mechanical destruction
Artificial valves
ECMO
HELLP syndrome
Excessive hemorrhage
Hemodialysis, extracorporeal circulation
Splenic Sequestration
Occurs in Sickle cell disease and Cirrhosis
Artificial valves
ECMO
Occurs in Sickle cell disease and Cirrhosis
sulfa antibiotics, ETOH, ASA, thiazide diuretics/furosemide
Hemolytic uremic syndrome
Gastroenteritis
Sickle cell crisis
Appendicitis
Hepatorenal syndrome
Colitis
Uremic bleeding syndrome
Intussusception