A simple

sensitive

accurate and reproducible protein binding assay of cAMP in platelet was established. The level of cAMP in platelet were determined in 30 normal subjects and in 26 patients with idiopathic thrombocytopenic purpura（ITP）. The results showed that the level of cAMP in ITP was significantly higher than those of normal group

and the concentration of cAMP in platelet was not correlated with plasma concentration. Finally

the methodology of cAMP in platelet and the causes of abnormality of cAMP in platelet during ITP were also- discussed.