ABSTRACT
A total of 29 subjects were studied which included 18 heart failure and 11 matched control cases. The underlying heart disease in heart failure cases was mostly chronic rheumatic valvular disease. The diagnosis of heart disease and heart failure was made on the basis of clinical examination, supplemented by electrocardiography, chest skiagram and echo cardiography. The serotonin status was assessed by measuring platelet serotonin uptake, intraplatelet serotonin content and whole blood 5-hydroxytryptamine (5-HT) levels. Blood platelet count was also done. In heart failure cases, platelet count were significantly less, the platelet 5-HT uptake and blood 5-HT levels remain unaltered. These findings indicate that platelet pool of serotonin does not contribute to raised serotonin blood levels in heart failure. The high blood serotonin levels may be due to either clearance defect or enhanced secretion from the gut or both. The altered serotonin kinetics in platelets also indicate a state of platelet activation in heart failure.