amenorrhea /ā′menərē″ə/ [Gk, a, men, not month, rhoia, to flow] , the absence of menstruation. Amenorrhea is normal before sexual maturity, during pregnancy, after menopause, and during the intermenstrual phase of the monthly hormonal cycle; it is otherwise caused by dysfunction of the hypothalamus, pituitary gland, ovary, or uterus; by the congenital absence or surgical removal of both ovaries or the uterus; or by medication. It may also occur in women who are underweight or who exercise extensively. Primary amenorrhea is the failure of menstrual cycles to begin. Secondary amenorrhea is the cessation of menstrual cycles once established. Also spelled amenorrhoea. See also dietary amenorrhea, hypothalamic amenorrhea, postpill amenorrhea. −amenorrheic, adj.
