Menstrual Disorders - Causes

Amenorrhea

Normal causes of skipped or irregular periods include pregnancy, breastfeeding, hormonal contraception, and perimenopause. Skipped periods are also common during adolescence, when it may take a while before ovulation occurs regularly. Consistently absent periods may be due to the following factors:

Delayed Puberty. The most common cause of primary amenorrhea is delayed puberty due to some genetic factor that delays physical development.
Weight Loss and Eating Disorders. Extreme weight loss and reduced fat stores lead to hormonal changes that include low thyroid levels (hypothyroidism) and elevated stress hormone levels (hypercortisolism). These changes effect a reduction in reproductive hormones. A syndrome known as the female athlete triad is associated with hormonal changes that occur with eating disorders in young women who excessively exercise. It comprises anorexia (severe weight loss), amenorrhea, and osteoporosis (decrease in bone density).
Polycystic Ovarian Syndrome (PCOS). PCOS is a condition in which the ovaries produce high amounts of androgens (male hormones), particularly testosterone. PCOS occurs in about 6% of women, and amenorrhea or oligomenorrhea (infrequent menses) is quite common. According to a 2002 study, nearly 30% of obese women with PCOS had amenorrhea.
Elevated Prolactin Levels (Hyperprolactinemia). Prolactin is a hormone produced in the pituitary gland that stimulates breast development and milk production in association with pregnancy. High levels of prolactin (hyperprolactinemia) in women who are not pregnant or nursing can reduce gonadotropin hormones and inhibit ovulation, thus causing amenorrhea. It is the cause of between 10% and 40% of cases of secondary amenorrhea.
Premature Ovarian Failure (POF). POF is the early depletion of follicles before age 40. In most cases it leads to premature menopause. POF is a significant cause of infertility.
Structural Problems. In some cases, structure problems or scarring in the uterus may prevent menstrual flow. Inborn genital tract abnormalities may also cause primary amenorrhea. A specific malformation called Mullerian agenesis, in which no vagina or uterus develops, is rare but still causes about 16% of primary amenorrhea cases.
Stress. Physical and emotional stress may block the release of luteinizing hormone, causing temporary amenorrhea
Other Medical Conditions. Epilepsy, thyroid problems, celiac sprue, metabolic syndrome, and Cushing''s disease are associated with amenorrhea.

If the ovaries produce too much androgen (hormones such as testosterone) a woman may develop male characteristics. This ovarian imbalance can be caused by tumors in the ovaries or adrenal glands, or polycystic ovarian disease. Virilization may include growth of excess body and facial hair, amenorrhea (loss of menstrual period) and changes in body contour.