amenorrhea (āmĕn´ərē´a, əmĕn´–), cessation of menstruation. Primary amenorrhea is a delay in or a failure to start menstruation; secondary amenorrhea is an unexpected stop to the menstrual cycle. It is caused by dysfunctioning of the pituitary gland, ovaries, uterus, and hypothalamus, by surgical removal of the ovaries or uterus, by medication, or by emotional trauma. The result is an inadequate amount of body fat, calories, and protein to sustain menstruation. Female athletes have a higher than average rate of menstrual dysfunction, particularly amenorrhea, but the long-term effects of the exercise-related disorders are not known. It is also common among anorexics. The lack of estrogen, however, may contribute to the development of osteoporosis. Hormonal deficiencies over prolonged periods of time, particularly in combination with poor diets, may cause luteal phase deficiency and hypoestrogenic amenorrhea, which may last a long time. Methods of treatment include oral contraceptives or estrogen-progestin therapy.