Factors affecting the response to plasma therapy in thrombotic thrombocytopenic purpura.

Factors affecting the response to plasma therapy (plasma exchange and plasma infusion) were studied in four cases of thrombotic thrombocytopenic purpura (TTP) treated in our hospital. Plasma therapy led to recovery from advanced TTP, but three of the patients exhibited chronic relapse. The longer the period from onset, the more marked was the progression of TTP, from the first stage (thrombocytopenia alone) to the second stage in which thrombocytopenia was accompanied by microangiopathic hemolytic anemia (MHA), and the third stage in which neurological abnormalities appeared. Platelet thrombi, which are thought to be the primary pathogenetic feature, probably enlarge leading to stenosis of the vessels during the progression of TTP. Although the severity of TTP in the early stages could be judged from two markers, LDH and the platelet count, it was impossible to determine the severity of advanced TTP by these two markers. However, the severity of advanced TTP could be judged by including the grade and period of neurological abnormalities. The dose of plasma needed to induce recovery was small in the early stage, but as the period from onset lengthened, the dose had to be increased. Though the early platelet thrombi might be easily eliminated by plasma infusion, larger and well-established platelet thrombi might not be lysed even by massive doses of plasma.(ABSTRACT TRUNCATED AT 250 WORDS)