Hypogonadotropic hypogonadism

Hypogonadotropic hypogonadism (HH) or secondary hypogonadism is defined as a clinical syndrome that results from gonadal failure due to abnormal pituitary gonadotropin levels. HH may result from either absent or inadequate hypothalamic gonadotropin releasing hormone (GnRH) secretion or failure of pituitary gonadotropin secretion. HH can be congenital or acquired. Congenital HH is clinically and genetically heterogeneous. Clinically, the disorder is characterized by an absence of puberty and infertility. The genetic condition is classically divided in 2 groups based on the presence or absence of olfaction dysfunction. Around 50-60% of the affected individuals exhibit anosmia or hyposmia in association with IHH, defining Kallmann syndrome. Acquired HH can be caused by drugs, infiltrative or infectious pituitary lesions, hyperprolactinemia, encephalic trauma, pituitary/brain radiation, exhausting exercise, abusive alcohol or illicit drug intake, and systemic diseases such as hemochromatosis, sarcoidosis and histiocytosis X.