label: Gonadotropin-releasing hormone deficiency
label_lc: gonadotropin-releasing hormone deficiency
description: Gonadotropin-releasing hormone (GnRH) deficiency (IGD) is characterized by inappropriately low serum concentrations of the gonadotropins LH (luteinizing hormone) and FSH (follicle-stimulating hormone) in the presence of low circulating concentrations of sex steroids (primarily testosterone or estradiol). GnRH is not typically assayed directly because it is released in pulses from the hypothalamus, and its concentration can fluctuate rapidly and in a complex pattern that makes single blood measurements less informative than the pituitary's response.