HYPOLEPTINEMIA IN WOMEN ATHLETES - ABSENCE OF A DIURNAL RHYTHM WITH AMENORRHEA

The possibility that chronic nutritional deficiency alters leptin regu lation and its link to reproductive function was investigated by deter mining serum leptin levels during a 24-h period with controlled nutrie nt intake in highly trained athletes with and without menstrual cyclic ity and in BMI-matched cycling sedentary controls (n = 8 per group). O ur data show that 24h leptin levels were reduced equally (3-fold, P < 0.001) in both cyclic and amenorrheic athletes as compared to controls . Low leptin levels in the athletic groups were consistent with their reduction in body fat (r = 0.91, P < 0.0001) relative to BMI, but were also influenced by the presence of low insulin (r = 0.70, P < 0.001) and elevated cortisol (r = -0.65, P < 0.001) levels. A diurnal pattern of 24h leptin levels, with an approximate 50% rise (P < 0.001) from n adir (0900h) to peak (0100h), was present in normally cycling athletes and controls and was strikingly absent in amenorrheic athletes. The a bsolute increase in leptin levels from nadir to peak was directly rela ted to insulin excursions in response to meals (r = 0.60, P = .002) an d inversely related to the amplitude of the 24h cortisol rhythm (r = - 0.70, P = .0002). These findings are consistent with a link between th e functionality of adipocytes, nutritional status, and integrity of th e reproductive axis in humans.