Ghrelin promotes the release of growth hormone, elevates food intake and induces obesity [1]. In healthy children, ghrelin concentrations are inversely correlated with body mass index and age [2]. Circulating ghrelin levels of humans do not show gender-related differences [3]. In adult patients with end-stage renal disease (ESRD), a three-fold rise in plasma ghrelin levels has been reported. Bilateral nephrectomy in mice causes a marked increase of plasma ghrelin levels. Ghrelin concentrations decline significantly during haemodialysis (HD) [4]. It was the objective of the present study to investigate whether ghrelin is elevated in serum of paediatric patients with renal failure and whether it is eliminated by HD, because there have been no data in children so far.
Subjects and methods. Ghrelin concentrations were measured in serum of eight chronic HD patients, six automated peritoneal dialysis (APD) patients and 14 patients with chronic renal failure (CRF) not yet on dialysis. Each patient group was compared with a control group of healthy children matched according to BMI and age. Patient data are shown in Table 1. Serum ghrelin before and after HD was compared. Furthermore, ghrelin concentrations in dialysate samples collected 5 min after the beginning and after 1, 2, 3 and 3.54.5 h of dialysis were evaluated. Immunoreactive ghrelin concentrations were measured using a commercial radioimmunoassay (Phoenix Pharmaceuticals, Belmont, CA) [5]. MannWhitney test was performed to compare patient groups with control groups. Paired values were compared using Wilcoxon matched pairs test. A P value of <0.05 was considered significant.
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Discussion. Our results show that ghrelin is significantly elevated in serum of children with CRF or ESRD treated by HD or APD. Ghrelin is cleared by HD. This is consistent with data in adults [4]. The high clearance of ghrelin either suggests a powerful counter-regulation of serum ghrelin by increased secretion or high tissue concentrations. In case of a long-lasting normalization, ghrelin may provide an additional mechanism negatively influencing energy intake and growth hormone secretion in HD patients.
Conflict of interest statement. None declared.
Department of Pediatrics University of Erlangen-Nürnberg Loschgestrasse 15 D-91054 Erlangen Germany
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