Predictors of outcome of long-term GnRH therapy in men with idiopathic hypogonadotropic hypogonadism

This retrospective study from Massachusetts General Hospital evaluated the predictors of success of prolonged pulsatile GnRH therapy in 76 men with idiopathic hypogonadotropic hypogonadism (IHH), treated for 12 to 24 months. IHH is a condition characterized by deficient production of gonadotropins (LH and FSH), resulting in hypogonadism and infertility.

The results demonstrated that the main predictor of therapeutic response was the presence of prior partial pubertal development (absent cryptorchidism, history of some virilization). Patients with evidence of prior gonadotropin exposure achieved:

• Normal testicular volume in 92% of cases
• Complete spermatogenesis in 100% of patients with prior pubertal development
• Normal testosterone levels in a sustained manner

In contrast, patients with complete absence of pubertal development (more severe form of IHH) showed more variable responses, although most still achieved significant virilization. The presence of uncorrected bilateral cryptorchidism was associated with worse spermatogenesis outcomes.

The study demonstrated that pulsatile GnRH therapy, by mimicking the physiological pattern of hypothalamic secretion, is superior in preserving gonadotropin pulsatility and inducing spermatogenesis compared to exogenous testosterone replacement therapy. The authors concluded that careful clinical assessment of the degree of prior pubertal development allows reasonably accurate prediction of GnRH therapy outcomes.