"Is It Normal for a Woman to Experience No Menstrual Cycle for Several Months?"

After the female reproductive system matures, menstruation occurs every month, typically lasting for three to seven days. The absence of menstruation for over two months constitutes amenorrhea. The cessation of menstruation for several months is an abnormal phenomenon, and it is advisable to seek medical attention. If pregnancy is ruled out, it is likely that menstrual irregularity is caused by gynecological disorders. Amenorrhea is defined as the absence of menstruation for more than two months. In teenage girls, the absence of menstruation by the age of 18, or in unmarried young women who have had normal menstruation but have stopped menstruating for over three months, is also considered amenorrhea.

1. Causes of Functional Amenorrhea

This type of amenorrhea is caused by various stress factors inhibiting the secretion of GnRH in the hypothalamus, which can be reversed with timely treatment.

1. Stress-induced Amenorrhea: Mental stress and changes in environment can lead to increased levels of endogenous opioids, dopamine, and adrenocorticotropic hormone (ACTH), thereby inhibiting GnRH secretion in the hypothalamus.
2. Athletic Amenorrhea: Athletes may experience amenorrhea after sustained intense exercise. This is related to psychological factors, stress response, and decreased body fat. Amenorrhea occurs when weight loss is 10% to 15%, or body fat loss is 30%.
3. Amenorrhea Due to Neurogenic Anorexia: Excessive dieting leads to a sharp decline in body weight, which ultimately reduces the secretion of various neuroendocrine hormones in the hypothalamus, causing decreased secretion of multiple pituitary hormones including LH, FSH, and ACTH. Clinical manifestations include anorexia, extreme emaciation, low Gn amenorrhea, dry skin, hypothermia, hypotension, low blood cell counts, and low plasma protein levels, which can be life-threatening in severe cases.
4. Nutrition-related Amenorrhea: Chronic consumptive diseases, intestinal diseases, and malnutrition can cause excessive weight loss and emaciation, leading to amenorrhea.

2. Genetic Defects or Organic Amenorrhea

1. Genetic Amenorrhea: Caused by congenital GnRH secretion defects due to genetic defects. This includes Kallmann syndrome with olfactory disturbances and idiopathic low Gn amenorrhea without olfactory disturbances. Kallmann syndrome is caused by KAL-1 gene defects on chromosome Xp22.3, while idiopathic low Gn amenorrhea is caused by mutations in the GnRH receptor 1 gene.
2. Organic Amenorrhea: Includes hypothalamic tumors, with craniopharyngioma being the most common, as well as inflammation, trauma, and chemotherapy.

3. Drug-induced Amenorrhea

Long-term use of drugs that suppress the central nervous system or the hypothalamus, such as antipsychotics, antidepressants, contraceptives, and metoclopramide, can inhibit GnRH secretion and cause amenorrhea. However, menstruation typically resumes after discontinuing these medications.