Absence of menstruation related to interference with release of gonadotropin-releasing hormone (GnRH) or with pituitary release of follicle-stimulating hormone or luteinizing hormone. Hypothalamic dysfunction may be drug-induced (e.g., related to abuse of marijuana or tranquilizers); psychogenic (e.g., related to chronic anxiety); functional (e.g., related to excessive exercise, anorexia, or obesity); or related to chronic medical illness, head injuries, or cancer.