Mixed Hypogonadism: A New Type of Hypogonadism

Abstract Purpose Kallmann syndrome is a rare disease characterized by delayed puberty, infertility and anosmia. We report the clinical and genetic characteristics of four patients with Kallmann syndrome who presented with Klinefelter syndrome or primary testicular disease and defined a new type of hypogonadism as mixed hypogonadism. Methods Clinical data and examinations were obtained, including laboratory examination and magnetic resonance imagination (MRI) of the olfactory structures. Idiopathic hypogonadotropic hypogonadism (IHH) related genes were screened by next generation sequencing (NGS). Results Four patients with Kallmann syndrome were included. Patient 1–3 had co-existence with Klinefelter syndrome and showed hypogonadotropic hypogonadism. Patient 1 was complicated with germinoma. Patient 4 had a history of hypogonadotropic hypogonadism and cryptorchidism, and then gradually converted to hypergonadotropic hypogonadism during follow-up. Conclusion Mixed hypogonadism was defined as hypogonadotropic hypogonadism in Klinefelter syndrome or primary testicular disease. Clinicians should be alert to mixed hypogonadism when spermatogenesis induction failed in patients with IHH or gonadotropin levels decrease in patients with Klinefelter syndrome.