Suggestion: amenorrhea can be divided into primary amenorrhea and secondary amenorrhea. Primary amenorrhea refers to those over 16 years old who have developed female secondary sexual characteristics and still have menstruation, or 14 years old who have not developed female secondary sexual characteristics. Secondary amenorrhea refers to those who stop for 6 months after the establishment of normal menstruation, or stop for more than 3 cycles according to their original menstrual cycle. Primary amenorrhea is rare and secondary amenorrhea is common. Common causes: Hypothalamic amenorrhea is the most common type of amenorrhea-mental stimulation, weight loss and anorexia nervosa, exercise amenorrhea, drug amenorrhea and craniopharyngioma. Pituitary amenorrhea-pituitary infarction, pituitary adenoma, empty sella syndrome. Ovarian amenorrhea-premature ovarian failure, ovarian functional tumor, polycystic ovary syndrome. Amenorrhea-Asherman syndrome is the most common cause of amenorrhea, and other endocrine functions are abnormal after endometritis, hysterectomy or intrauterine treatment.