Mr. R did exhibit four of the five signs, but did not have any neurologic deficits. TTP is often seen in conjunction with hemolytic uremic syndrome (HUS). The incidence of suspected TTP-HUS is 11 cases/million/year. There is a greater propensity for the disease in women and blacks.
In cases that are not idiopathic, etiology may be related to use of quinine, chemotherapeutic agents, immunosuppressive agents (e.g., cyclosporine,) and antiplatelet agents (e.g., clopidogrel and ticlopidine).2-4 Infectious causes are also noted to yield TTP-HUS. Shiga toxin released from E. coli can lead to HUS, especially in children.5 Thrombotic microangiopathy has been seen in HIV infection, and pneumococcal infection can also cause HUS in rare instances.6 TTP-HUS can be related to pregnancy or can be induced by oral contraceptives,7 and incidence has been linked to pancreatitis8 and to surgery.9
Left untreated, TTP-HUS can progress to renal failure, neurologic deterioration, cardiac ischemia and death. With the advent of plasma exchange, the mortality rate for this disorder has decreased from 90% to 20% in modern times. Mr. R received immediate plasmapheresis, which dramatically increased his platelet count. In patients with idiopathic TTP, as here, treatment with immunosuppressive agents such as prednisone is also recommended.1
After resolution of the acute TTP event, patients should be monitored with CBCs and LDH levels. In a study involving 63 subjects, the estimated 10-year relapse rate was 36%.10
Michele D. Tinge, MPAS, PA-C, is a physician assistant at Alton Internal Medicine in Alton, Ill.
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