TTP is an uncommon but severe consumptive platelet disorder. Its cause is unknown, but there are several possible precipitating factors including infection, carcinoma, and pregnancy.
More women than men are affected by TTP. If left untreated, the mortality rate is more than 90% due to multiorgan failure.
HUS is also a platelet consumptive disorder. HUS is thought by some to be the same condition as TTP because both disorders have the same underlying pathology. However, HUS is more often associated with renal failure and TTP with neurological manifestations including visual impairment, weakness, headache, dizziness, disorientation, seizures, or coma. Microangiopathic hemolytic anemia, thrombocytopenia, and fever are associated with both TTP and HUS. The patient's condition can deteriorate rapidly while these symptoms are becoming evident.
HUS is usually seen in children; it is the most common cause of acute renal failure in children. Patients may have bloody diarrhea and symptoms resembling colitis. Diarrhea-related HUS is usually associated with ingestion of undercooked beef contaminated with E. coli O157:H7; it is the Shiga-like toxin from this serotype that causes the illness. Some patients may have long-term kidney dysfunction as a result of this virulent infection. Patients who experience renal failure may require dialysis.