Low leptin levels are an endocrinological hallmark of acute anorexia nervosa (AN); a subthreshold leptin secretion in adipocytes as a consequence of a reduced energy intake is presumed to be the major trigger of the adaptation of an organism to semistarvation. The aim of the current study is to define symptoms of AN that are potentially linked to low leptin levels. For this purpose, quantitative somatic and psychopathological variables were obtained in 61 inpatients with acute AN (study group 1) upon referral for inpatient treatment, and they were concomitantly blood sampled to allow determination of serum leptin levels. Correlations between these variables and logarithmic transformed (lg10) leptin levels were descriptively assessed. Apart from the well-known correlations between leptin levels and anthropometric measurements, the strongest correlation was observed between lg10 serum leptin levels and expert ratings of motor restlessness (r = -0.476; nominal P = 0.003) upon use of visual analog scales. We thus generated the hypothesis that physical activity levels in AN patients are related to serum leptin levels. This hypothesis was tested in an independent study group of 27 adolescent inpatients (study group 2) who were also assessed upon referral. Physical activity levels, which, in this study group, were assessed with the activity module of the expert rating form of the Structured Inventory for Anorexic and Bulimic Syndromes, were significantly correlated with lg10 leptin levels (r = -0.51; one-sided P = 0.006). A regression model based on the independent variables body mass index and lg10 leptin levels explained 37% of the variance of physical activity (R(2) = 0.37; P = 0.003); only the lg10 leptin levels contributed significantly to the variance (P = 0.003). Our results suggest that, similar to semistarvation-induced hyperactivity in rats, hypoleptinemia in patients with AN may be one important factor underlying the excessive physical activity.
The aim of the study was to analyze the kinetics of short-term changes in bone turnover. We studied in a randomized crossover design the effects of 6 days of bed rest on eight healthy male subjects (mean body wt: 70.1 +/- 5.7 kg; mean age: 25.5 +/- 2.9 yr). The metabolic ward period was divided into three parts: 4 ambulatory days, 6 days of either bed rest or non-bed rest periods, and 1 recovery day. The diet was identical in both bed rest and non-bed rest phases. Continuous urine collection started on the first day in the metabolic ward to analyze excretion of bone resorption markers, namely C-telopeptide (CTX) and N-telopeptide (NTX), creatinine, urea, and 3-methylhistidine. On the second ambulatory day and on the fifth day of bed rest or during the non-bed rest phase, blood was drawn to analyze bone formation markers and amino acid concentrations. Urinary calcium excretion was increased as early as the first day of bed rest (P < 0.01). CTX and NTX excretion stayed unchanged during the first 24 h of bed rest compared with the non-bed rest period. However, already on the second day, both resorption markers had increased significantly. NTX excretion increased by 28.7 +/- 14.0% (P < 0.01), whereas CTX excretion rose by 17.8 +/- 8.3% (P < 0.001). Creatinine, urea, and 3-methylhistidine excretion did not change. We conclude that 24 h of bed rest are sufficient to induce a significant rise in osteoclast activity in healthy subjects.
In patients with anorexia nervosa (AN), an assessment of changes in body composition and nutritional status is crucial for adequate nutritional management during refeeding therapies. Phase-sensitive multifrequency bioelectrical impedance analysis (BIA) is an inexpensive and noninvasive technique with which to determine nutritional status and body composition. We investigated 21 female adolescents with AN (initial BMI 15.5 +/- 1.1 kg/m(2)) 4 times between wk 3 and 15 of inpatient refeeding and 19 normal-weight, age-matched female controls. From wk 3 to 15, BMI, fat mass, body cell mass (BCM), total body water (TBW), intracellular water (ICW) but not extracellular mass (ECM), and extracellular water (ECW) increased significantly. Reactance (Xc), phase angle (PhA), and the ECM/BCM index as parameters of nutritional status improved significantly in patients and no longer differed from controls in wk 15, although the BMI of patients was significantly lower than those of controls. Changes in the ECM/BCM index were due to accretion of BCM, which was associated with an increase of ICW. Multifrequency phase-sensitive BIA seems to be a promising tool for the assessment of changes in nutritional status and body composition in patients with AN. An individually determined and controlled hyperenergetic diet as part of a multidimensional, interdisciplinary treatment program for eating disorders seems to quickly improve the nutritional status of AN patients.
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