The causes of functional uterine bleeding in adolescence.

Dysfunctional uterine bleeding may be anovulatory or ovulatory , but anovulatory is more common , long-term anovulation or chronic anovulation . The reproductive cycle of a normal woman is a constantly moving system , which has long fluctuation cycles measured in months and short fluctuation cycles measured in minutes and seconds . Any factor that interferes with these regular dynamic rhythms can affect ovarian function . The main parts affected are any link in the central nervous system and the hypothalamus - pituitary - ovarian axis , which leads to menstrual disorders .

Puberty is an orderly maturation process involving the central nervous system, hypothalamus, pituitary gland, gonads, and sex hormone target organs . Each link responds differently to nerve or hormonal stimulation in terms of structure according to their sensitivity or changes in their endocrine environment . During puberty, the hypothalamus - pituitary - ovarian axis gradually decreases in sensitivity to negative feedback of sex hormones , which increases the synthesis and release of LRF ( luteinizing hormone-releasing factor ) , thereby increasing the secretion of gonadotropins , including the increase in LH secretion during sleep , and finally the maturation of the positive feedback mechanism to estrogen , which can cause the LH ( luteinizing hormone ) peak in the middle of the menstrual cycle , followed by ovulation .

The blood E1 and E2 levels of adolescent patients with functional uterine bleeding are within the normal range . The negative feedback mechanism of estrogen and gonadotropin is also normal during the same period . The reason why these patients do not ovulate is that the pituitary gland has a positive feedback defect on estrogen and cannot release enough LH. Under the continuous action of estrogen , different degrees of hyperplastic endometrium may appear . Excessive hyperplasia of adenocystic endometrium is not common , and secretory endometrium may occasionally occur .