Based on the findings, "when someone's got irregular menstruation, eating disorders should be on the radar screen," Dr. Cynthia M. Bulik of the University of North Carolina at Chapel Hill, the study's lead author, told. Missing periods raises a woman's risk of osteoporosis, Bulik noted, and may also impair fertility.

According to current diagnostic criteria, anorexia nervosa is the only eating disorder subtype associated with menstrual irregularities, Bulik said. A woman must have absence of menstrual periods for at least three months to be diagnosed with anorexia nervosa.

But in a survey of 1,705 women participating in a genetic study who met strict diagnostic criteria for eating disorders, Bulik and her team found menstrual irregularities including absence of periods, skipping periods, and very light periods among women with every subtype of eating disorder, including bulimia nervosa.

The factors most strongly associated with menstrual dysfunction included a person's body mass index (BMI), her calorie intake, and her level of exercise. Women who menstruated normally had the highest maximum and minimum lifetime BMIs, the researchers note, but even some women of normal weight reported menstrual irregularities.

The findings suggest to Bulik and her colleagues that menstrual status "might not be an informative criterion to distinguish among eating disorder subtypes."

Doctors currently only screen patients for eating disorders if they are underweight, Bulik said. But based on her findings, she added, "menstrual irregularities should be a red flag for all physicians to ask about eating disorders."

Source: International Journal of Eating Disorders