Hypogonadism in a male-to-female transsexual with super obesity

The global obesity epidemic is having a profound impact on the health of populations. From a reproductive standpoint, obesity has been associated with infertility and hypogonadism. We present the case of a 29-year-old male-to-female transsexual with super obesity (body mass index >50) who was found to have profound hypogonadism with total and free testosterone levels in the normal female reference range. There is virtually no literature on the hormonal sequelae of obesity in transsexual people. The patient was prescribed an aromatase inhibitor, letrozole 2.5mg twice daily for 2weeks, to determine the role of oestrogen in the hypogonadism. The aromatase inhibitor reduced the serum oestradiol concentration from 125 to 6.9pm. There were dramatic corresponding rises in total testosterone (2.8 to 10.7nm), luteinising hormone (4.1 to 20.5mIUml(-1)) and follicle stimulating hormone (1.8 to 15.3mIUml(-1)). This diagnostic test demonstrated the important role of oestrogen in mediating the hypogonadism. After the testing, the patient was started on oestrogen therapy after a careful discussion of the benefits versus risks of oestrogen therapy. We anticipate that similar cases of hypogonadism in male-to-female transsexuals will likely become more common in an era of increased obesity rates.