Circadian plasma leptin levels in patients with anorexia nervosa: Relationto insulin and cortisol

In anorexia nervosa, underweight results from a loss of body mass due to a restricted energy intake, Circulating leptin levels have been shown to be l ow in the acute stage of the disorder, We studied diurnal secretion charact eristics of leptin, insulin and cortisol in a study group of anorectic pati ents prior to refeeding, a second study group of anorectic patients after i nitiation of refeeding and study groups of healthy underweight and normal-w eight controls, Spontaneous secretion of leptin, insulin and cortisol was m easured by drawing blood samples every 2 h for 24 h, The temporal relations hips between the diurnal secretion patterns of the three hormones were asse ssed by cross-correlation analysis in every study group, Plasma levels of l eptin and cortisol were secreted with a specific circadian rhythmicity and displayed an intricate temporal relationship in anorectic patients, Semista rvation in the non-refed patients was associated with (1)exceedingly low pl asma leptin levels, (2) a qualitative alteration in the circadian rhythm of leptin and cortisol levels and (3) an alteration in the temporal coupling between cortisol and leptin, In contrast, in the patients who had gained we ight, leptin levels were higher; furthermore, the diurnal pattern of leptin and the temporal relationship between leptin and cortisol were similar to controls, Increments in insulin secretion preceded those of leptin by 4-6 h in both anorectic patients and in controls, Leptin levels increased 4 h pr ior to those of cortisol in controls and in refed patients, whereas in the non-refed patients cortisol increased prior to leptin, Thus, anorexia nervo sa leads to pronounced, albeit reversible changes in the secretion dynamics of leptin and cortisol.