SAN FRANCISCO — Athletic teenage girls who are amenorrheic have higher ghrelin and lower leptin levels than do athletic girls who are eumenorrheic or girls who are nonathletic, according to a small study.
The findings could help tease out which girls are more likely to stop menstruating, said study investigator Dr. Madhusmita Misra of Harvard Medical School.
Dr. Misra, a pediatric endocrinologist at Massachusetts General Hospital for Children, Boston, presented the study results at the annual meeting of the Endocrine Society. She and her colleagues aimed to determine whether ghrelin, which stimulates appetite, and leptin, which suppresses appetite, might be related to amenorrhea in young women, especially those with intense energy expenditures and a heightened need for caloric intake. Ghrelin levels have been shown to be increased in people with anorexia nervosa, and higher levels also have been linked to impaired secretion of hormones that regulate menstrual and ovarian function.
“The hormonal factors that link energy deficit and the stopping of periods in athletes are not well characterized,” said Dr. Misra, who spoke with reporters during the meeting.
The study was funded by the National Institutes of Health.
It is especially important to tease out the relationships, given that evidence suggests that amenorrhea causes infertility and early onset of low bone density, she said. Some 25% of female high school athletes experience an absence of menstruation.
Dr. Misra and colleagues enrolled 21 girls who were amenorrheic athletes, 19 eumenorrheic athletes, and 18 nonathletic controls. All were aged 12–18 years. Fasting blood was drawn to measure ghrelin, leptin, estradiol, testosterone, and follicle-stimulating hormone levels.
The two athletic groups had similar activity levels, which were higher than that for the control group of nonathletes. The athletes were 85% of ideal body weight for their age.
But the amenorrheic girls weighed less and had lower body mass index scores than did eumenorrheic girls. They also had slightly disordered eating behaviors—which included dieting—but no use of laxatives or medications to lose weight, said Dr. Misra.
As predicted, the amenorrheic girls had lower leptin levels—half those of the other two groups—and their ghrelin levels were twice those of the other two arms. The girls with the highest ghrelin levels and lowest leptin levels also had the lowest levels of estrogen and of follicle-stimulating hormone, she said.
In an interview, Dr. Misra said that it was not clear whether these hormone disturbances existed before the onset of amenorrhea, but that she was leaning toward a hypothesis that the hormone disturbances are an adaptive response in some girls.
Moreover, these girls might have an intrinsic abnormality that causes that response in the face of energy demands.
Dr. Misra has applied to the NIH for funding of a prospective study more closely examining energy availability and its affect on hormones.
She stated that she had no conflicts of interest related to this study.