Leptin secretion is related to chronicity and severity of the illness in bulimia nervosa

A reduction in circulating leptin has been reported in some patients with BN, but not in others. The reasons for such diversity have not been explained. Therefore, we measured plasma levels of leptin and other hormones in a large sample of patients with eating disorders and in healthy controls and explored differences between bulimics with low plasma leptin levels and those with normal concentrations of the hormone.

One hundred and twenty-seven women participated in the study. They were 33 patients with AN, 56 women with BN, and 38 healthy volunteers. All were drug free for at least 6 weeks. Blood samples were collected in the morning for determination of hormone levels. Eating-related psychopathology and depressive symptoms were rated by using specific psychopathological scales.

As compared with healthy women, both underweight AN and normal-weight BN patients exhibited decreased plasma levels of leptin, prolactin, and 17beta-estradiol. Plasma levels of cortisol were increased in AN but not in BN women. In bulimics, circulating leptin was inversely correlated with the duration of the illness and the frequency of bingeing/vomiting. Moreover, 29 bulimics had anorexic-like plasma leptin concentrations; the remaining 27 had circulating leptin similar to normal controls. The former had a significantly longer duration of the illness and a higher frequency of bingeing/vomiting compared with the latter. Moreover, a higher number of patients with concomitant borderline personality disorder were found in bulimics with low leptin concentrations. No significant differences between the two groups emerged in BW, BMI, mean plasma levels of cortisol, PRL, 17beta-estradiol and other clinical parameters.

Present data show that leptin production is decreased in the subgroup of bulimic patients with a more chronic disease and with a greater severity of the bingeing/vomiting behavior. These findings support the idea that factors other than body weight changes (especially chronic malnutrition and bingeing behavior) may impair profoundly and persistently leptin secretion in patients with BN.