Gynecomastia and hypogonadism can occur during treatment with a range of antidopaminergic drugs and is most likely to a medication induced increase in serum prolactin levels. However there is little evidence for an association between antidepressants and hypogonadism.

We report the case of a 23 year old male with a 3 year history of bulimia nervosa and recurring depression who had been treated with duloxetine for a period of 6 months during which he developed pronounced bilateral gynocomastia. Since serum prolactine and serum testosterone levels were normal and duloxetin was initially not considered causative, the drug was continued and bilateral gynecomastia was performed. 4 months later the patient again experienced tension and swelling in the breast.

The endocrinologic exams revealed reduced serum testosterone levels and reduced testicular volume. Body weight was 63 kg, height 176 cm and a neurological exam, including olfactory testing and MR brain imaging was normal. Hypogonadotropic hypogonadism was diagnosed.

Increased prolactin levels under antipsychotic medications are not uncommon. Some rare instances of gynecomastia have been reported under fluoxetine and venlafaxine, always associated with increased serum prolactin levels. In the present case the close tempral relationship between initiation of duloxetine and the development of gynecomastia and the recurrence under continued medication and resolution after termination of the medication suggests a possible causal relationship. The normal prolactin levels argue against anvolvement of prolactin in the pathogenesis. We suspect a prolactine independent mechanism.