Abstract
BackgroundThe influence of serum leptin levels on nutritional status and survival in chronic hemodialysis patients remained to be elucidated. We conducted a prospective longitudinal study of leptin levels and nutritional parameters to determine whether changes of serum leptin levels modify nutritional status and survival in a cohort of prevalent hemodialysis patients.MethodsLeptin, dietary energy and protein intake, biochemical markers of nutrition and body composition (anthropometry and bioimpedance analysis) were measured at baseline and at 6, 12, 18 and 24 months following enrollment, in 101 prevalent hemodialysis patients (37% women) with a mean age of 64.6 ± 11.5 years. Observation of this cohort was continued over 2 additional years. Changes in repeated measures were evaluated, with adjustment for baseline differences in demographic and clinical parameters.ResultsSignificant reduction of leptin levels with time were observed (linear estimate: -2.5010 ± 0.57 ng/ml/2y; p < 0.001) with a more rapid decline in leptin levels in the highest leptin tertile in both unadjusted (p = 0.007) and fully adjusted (p = 0.047) models. A significant reduction in body composition parameters over time was observed, but was not influenced by leptin (leptin-by-time interactions were not significant). No significant associations were noted between leptin levels and changes in dietary protein or energy intake, or laboratory nutritional markers. Finally, cumulative incidences of survival were unaffected by the baseline serum leptin levels.ConclusionsThus leptin levels reflect fat mass depots, rather than independently contributing to uremic anorexia or modifying nutritional status and/or survival in chronic hemodialysis patients. The importance of such information is high if leptin is contemplated as a potential therapeutic target in hemodialysis patients.
Highlights
The influence of serum leptin levels on nutritional status and survival in chronic hemodialysis patients remained to be elucidated
Cross-sectional associations The 101 prevalent HD patients participating in this study included 36.6% women; over half of the participants (51.5%) had diabetes mellitus (DM) and nearly the same proportion had a history of cardiovascular disease (46.9%), including myocardial infarction, coronary artery procedures such as angioplasty or surgery, previous cerebral-vascular accident, or peripheral vascular disease
No significant differences in any of the biochemical markers of nutrition, normalized protein nitrogen appearance, or actual energy or protein intake normalized to adjusted body weight were found between the HD patient groups according to leptin tertiles
Summary
The influence of serum leptin levels on nutritional status and survival in chronic hemodialysis patients remained to be elucidated. In some observational studies, increased serum leptin concentrations were observed in ESRD patients in parallel with loss of lean body mass [18,19] or with hypoalbuminemia and low protein intake [20], some others failed to find any correlation between hyperleptinemia and weight change [9] or lean mass [21] in this population. Several clinical studies suggested that leptin is a negative acute phase protein [22] and can serve as a marker of adequate nutritional status, rather than an appetite-reducing uremic toxin in hemodialysis patients [23,24,25]. In one small prospective cohort of hemodialysis patients, lower baseline serum leptin levels predicted mortality [26], but neither changes in leptin over time were measured, nor were leptin levels normalized to body fat mass in this study
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