Endocrine Abstracts

Idiopathic hypogonadotropic hypogonadism (IHH) is caused by an isolated defect in GnRH release or action and classified as the Kallmann syndrome with associated anosmia or normosmic IHH in the presence of a normal sense of smell. Patients with IHH have absent or incomplete sexual maturation and infertility. Usually long term GnRH or gonadotropin therapy in these patients can induce spermatogenesis and puberty and is followed by testosterone therapy to maintain normal virilization. But in some patients with IHH brief discontinuation of testosterone replacement therapy probably results in reversal of IHH.

Material and methods: We observed prospectively 16 men with delayed of puberty and IHH (two had anosmia). At initial evaluation, all men had absent puberty and all had abnormal secretion of GnRH-induced LH and FSH levels and mean testosterone levels 0.81±0.14 ng/ml (2.75±0.61 nmol/l). All men had received testosterone replacement therapy to induce virilization and after 9–12 months the treatment was followed by 8 weeks of treatment discontinuation with next evaluation. Reversal IHH was defined as testosterone levels above 2.5 ng/ml.

Results: In two men serum levels of endogenous testosterone increased from 0.82±0.19 ng/ml (2.78±0.64 nmol/l) to 3.69±0.81 ng/dl (12.5±2.75 nmol/l, P<0.001), LH and FSH levels also increased (2.3±1.8 to 7.9±2.9 IU/l (P<0.001) and 2.7±1.9 to 8.9±9.6 IU/l (P<0.01) respectively). The mean testicular volume increased from 7±4 to 15±4 ml (P<0.001) and spermatogenesis was initiated. In 14 men we did not observed statistical significant changes of LH and FSH levels after discontinuatopn of testosterone replacement therapy.

Conclusions: We documented reversal IHH in men with delay of puberty after relative short-time testosterone replacement therapy.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.