Bone density in the adolescent athlete.

Adolescence is a critical time for bone mass accrual, and increases in bone mass through puberty are dependent on rising levels of gonadal steroids, growth hormone and insulin like growth factor-1. Many high school girls are involved in athletic activities, and as many as 23.5% of adolescent athletes have been reported to develop amenorrhea. This review focuses on (1) factors that determine which athletes are likely to develop amenorrhea, such as a negative energy balance state, low levels of leptin and high levels of ghrelin, and (2) the impact of hypogonadism in athletes on bone metabolism. Beneficial effects of increased mechanical loading from athletic activity do not appear to protect against the deleterious effects of hypogonadism in adolescent athletes.