The blood counts and lactate dehydrogenase levels in thrombotic thrombocytopenic purpura (TTP).

The blood counts and lactic dehydrogenase values of eight patients with thrombotic thrombocytopenic purpura (TTP) were reviewed in relation to the clinical course. Three of the eight patients died. In these patients, the hemoglobin was significantly lower and the LDH higher at the time of presentation than that of the patients responding to treatment. The height of the absolute reticulocyte count and platelet count did not correlate as well with outcome as did the degree of anemia and LDH elevation. Microangiopathic changes were noted in all eight patients. A differential count showed that the total microangiopathic changes varied from 0.8 to 54%. The more severe microangiopathic changes occurred in the fatal cases. The observations indicate that the degree of anemia, elevation of LDH, and severity of microangiopathic changes at the time of presentation correlate with the outcome in TTP and provide useful parameters in the assessment of response to therapy.