Serotonergic function in panic disorder: endocrine responses to D-fenfluramine.

1. Prolactin and cortisol responses to d-fenfluramine were measured in 16 patients with DSM-III-R panic disorder and 14 normal controls. 2. Patients showed a greater mean prolactin response than controls but the difference between groups was not statistically significant (P > 0.05, MANOVA). 3. No consistent differences were observed between patients and controls with respect to cortisol responses (P > 0.05, MANOVA). 4. The results do not support the hypothesis of hypersensitive post-synaptic serotonin receptors in patients with panic disorder. 5. Studies in larger groups are necessary to confirm the trend and to explore receptor subtype sensitivity.