cessation of periods, secondary amenorrhea, secondary amenorrhoea
Cessation of menstruation, also called secondary amenorrhea, is the condition in which menstrual cycles disappear for 6 consecutive months in a girl with irregular menses or for 3 consecutive months in a girl with regular menses.
Girls with disorders of the hypothalamus are susceptible to the development of secondary amenorrhea, due to an insufficient secretion of gonadotropin-releasing hormone (GnRH) leading to low levels of basal plasma gonadotropins and estradiol. However, after stimulation with exogenous gonadotropin-releasing hormone, the secretion of gonadotropins is in the physiological range. Dysfunctional causes of hypothalamic amenorrhea include psychogenic stress, excessive physical activity and nutritional disorders.
Psychogenic stress arises from emotional or mental stressors. It seems to induce the secretion of high levels of corticotrophin-releasing hormone (CRH), which inhibits gonadotropin-releasing hormone pulses.
Excessive physical activity
Also girls performing excessive physical activity are prone to present hypothalamic amenorrhea and short luteal phases. These abnormalities are induced by the strenuous physical activity and the restricted caloric intake requested to maintain leanness. Athletes show frequently a strong disproportion among nutritional intake and real energy expenditure, especially in disciplines where low body weight for performance and aesthetics is needed. In particular, in athletes there is a risk of amenorrhea three times higher than in general population, with predominance between long-distance runners.
Among the most important eating disorders, anorexia nervosa and bulimia nervosa (binge eating followed by purging) affect up to 5% of women of reproductive age causing amenorrhea and infertility.
Causes of secondary amenorrhea can also result in primary amenorrhea, especially if present before onset of menarche. Primary amenorrhea refers to the failure of a period to start by the age of 16, in the presence of otherwise normal growth and development of secondary sexual characteristics (e.g. breast development, pubic hair) or, the failure of onset of puberty by the age of 13. The cessation of menstrual cycles at the end of a woman's reproductive period is termed menopause.
In details, anorexia nervosa has been defined as body weight less than 85% of expected weight or body mass index less than 17.5 kg/m2, caloric restriction, fear of weight gain and an impaired perception of body image. In fact, a decrease of 10-15% in normal body weight seems to be able to cause cessation of menstruation.
Actually the precise mechanisms through which excessive stress and weight loss influence negatively gonadotropin-releasing hormone secretion are still uncertain. Furthermore, the lately discovered leptin, one of the most important adipose derived hormones which play a key role in regulating energy intake and expenditure, seems to be strictly involved into the mediation of reproductive axis. Low levels of leptin have been reported in women with hypothalamic amenorrhea. However, in these girls the impaired production of gonadotropin-releasing hormone (GnRH) may have several implications on estrogen secretion.
During the menstrual cycle, estogens (estradiol) produced by the growing follicle triggers, via a positive feedback system, the hypothalamic-pituitary events that lead to the luteinizing hormone (LH) surge, inducing ovulation. Estradiol also acts as grow hormone in uterus lining whose periodic shedding and growing is the basis of menstrual periods. In leptin deficiency women, this mechanism is dimished as a result of GnRH deficiency leading to estradiol deficiency. These hormone imbalances then cause the cessation of menstruation.