Amenorrhea, or absence of menstruation, occurs in as many as 25 percent of female high school athletes, compared with 2 to 5 percent in the general population, according to the study's presenter, Madhusmita Misra, MD, a pediatric endocrinologist at Harvard-affiliated Massachusetts General Hospital, Boston.
Amenorrhea in athletes is known to cause infertility and early onset of low bone density and may increase the risk of breaking bones. Evidence suggests that intense exercise associated with caloric restriction, and therefore a state of energy deficit, is most responsible for menstrual irregularities among athletes.
In females ages 12 to 18, Misra and her colleagues measured levels of various hormones, including ghrelin. Giving ghrelin to animals and humans has been shown to cause impaired secretion of hormones that regulate ovarian and menstrual function, and ghrelin levels are elevated in people with anorexia nervosa, another condition of severe energy deficit, she said. Until now, ghrelin levels have not been studied in teenage athletes in relation to ovarian hormones.