During the transition from menarche to a normal ovulatory cycle, a number of influences and noxae may cause abnormalities. The hypothalamicpituitary- ovarian axis is complex, unstable and vulnerable. This lability, particularly in puberty and adolescence, is responsible for the frequent occurrence of menstrual cycle disturbances. Physical, psychological and social stresses can influence pulsatile GnRH secretion and consequently the secretion of gonadotropins. In adolescence this can cause primary menstrual irregularities as well as secondary abnormalities. Other reasons for disturbances are chronic illness and systemic diseases, liver disease, renal failure and medications.

Endocrine conditions include adrenal disorders, hyperandrogenemia, hyperprolactinemia and abnormal thyroid function.

Prostaglandins play an important role in menstrual bleeding, and an imbalance may be a factor in the pathophysiology of irregular uterine bleeding.

Progesterone from the corpus luteum, a key factor for normal menstruation, activates prostaglandin production in endometrial cells. Normally, bleeding is stopped by constriction of endometrial arterioles and vascular stasis by platelet and thrombin plugs and fibrin deposition. Hematologic conditions such as coagulation disorders and defects are relatively common.

Organic causes such as genital tract diseases and uterine pathology or neoplasms are rare in adolescence, but have to be kept in mind and ruled out.
Pregnancy-related problems must be excluded.