The hormone leptin may aid female fertility

Twice-daily injections of the hormone leptin, best known for regulating appetite and weight, may be able to jump-start an idling reproductive system.

Doctors found that the treatment restored menstruation in five of eight female athletes who were so lean they had stopped having periods. Leptin is a naturally occurring hormone produced by fat cells, so athletes, dancers and other thin people may have less of it. It is also being studied for its role in obesity.

But the researchers did not give placebo shots to the other six volunteers, so a more thorough two-year test of 80 women is poised to begin to see if the Amgen version of leptin, used in the pilot study, really works.

Christos Mantzoros of Beth Israel Deaconess Medical Center in Boston said leptin had the potential to help women with the eating disorder anorexia nervosa, physically active women who have stopped menstruating, and very thin women who don’t realize they have a problem until they can’t conceive. The study, financed in part by Amgen, appeared in last week’s New England Journal of Medicine.