Platelet serotonin-binding (Bmax), using tritiated-seroionin as the ligand, was determined in 75 patients suffering from major depression with melancholia and in 26 patients diagnosed from dysthymic disorder. Twenty-five normal subjects were used as a control group. The melancholic group had significantly lower Bmax values (mean: 6.7 ± 6.1 pmol/108 platelets) than either dysthymic (9.3 ± 3.9 pmol/108 platelets) or control (9.2 ± 4.8 pmol/108 platelets) groups, while there were no significant differences between the two latter groups. There was also a significant difference on postdexamethasone Cortisol between melancholic (6.3 ± 7.1 μg/dL) and dysthymic (1.4 ± 1.4 μg/dL) groups, with a higher rate of nonsuppressors in melancholic groups. Although both tests were abnormal in the melancholic group, no relationship was found between platelet serotonin-binding and the dexaniethasone suppression test.
