Menstrual Irregularities: Amenorrhea
In order to understand menstrual irregularities, one must be comfortable in understanding the menstrual cycle. The first half of the menstrual cycle from day 0–14 is termed the follicular phase. It begins with menses, which is the uterine withdrawal bleed that occurs from day 0 until day 5–7. Ovulation occurs midway through the cycle usually between days 10–14. If fertilization does not occur, the egg involutes into a corpus luteum, which produces progesterone. This occurs in the second half of the menstrual cycle and is termed the luteal phase. Normal menses occur every 21–35 days. Below is outlined the variations in follicle-stimulating hormone (FSH) and luteinizing hormone (LH) levels, and the corresponding changes in estrogen and progestin throughout the cycle (Fig. 1).
KeywordsMenstrual Cycle Anorexia Nervosa Eating Disorder Congenital Adrenal Hyperplasia Turner Syndrome
References and Additional Readings
- Emans S. J. Amenorrhea in the Adolescent. In: Emans SJ, Laufer MR, Goldstein DP, Eds. Pediatric and Adolescent Gynecology. 5th edn. Philadelphia, PA: Lippincort Williams & Wilkins, 2005, pp. 214–70.Google Scholar
- Gamboa S. Clinical inquiries: What’s the best way to manage athletes with amenorrhea? J Fam Prac 2008;57:749–50.Google Scholar
- Gordon C. Amenorrhea. In: Neinstein LS, Ed. Adolescent Health Care. Philadelphia, PA: Lippincott Williams & Wilkins, 2002, pp. 973–95.Google Scholar