Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are found in hypogonadism, anorchia, gonadal failure, complete testicular feminization syndrome, menopause, Klinefelter syndrome, alcoholism, and castration. FSH and LH are pituitary products, useful to distinguish primary gonadal failure from secondary causes of gonadal failure, menstrual disturbances, and amenorrhea. It is useful in defining menstrual cycle phases in infertility evaluation of woman and testicular dysfunction in men. FSH is commonly used with LH. both FSH and LH are low in pituitary or hypothalamic failure and are high following menopause. Secretion of both LH and FSH are pulsatile, in response to the normal intermittent release of gonadotropin releasing hormone (GnRH). In addition, in females both FSH and LH vary over the course of the menstrual cycle, with peaks at time of ovulation. Thus, interpretation of a single determination may be difficult.