Effect of renal failure and dialysis on circulating ghrelin concentration in children

Sir,

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 3.5–4.5 h of dialysis were evaluated. Immunoreactive ghrelin concentrations were measured using a commercial radioimmunoassay (Phoenix Pharmaceuticals, Belmont, CA) [5]. Mann–Whitney 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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Table 1. Data of patient groups and control groups matched according to BMI and age

 
Results. Ghrelin was detected in all dialysate samples. Its dialysate concentration remained stable during the HD session (data not shown). The amount of cleared plasma ranged from 2.46 to 2.93 l/h. Ghrelin in serum declined significantly (P<0.03) during HD. It was significantly elevated in HD patients before HD compared with healthy subjects (P<0.05). No significant difference to healthy children was observed after HD. In APD patients (P<0.001) and CRF patients (P<0.03), we observed a significant elevation as well, compared with healthy controls. For results see Table 1.

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.

Kai-Dietrich Nüsken, Michael Gröschl, Manfred Rauh, Wolfgang Stöhr, Wolfgang Rascher and Jörg Dötsch

Department of Pediatrics University of Erlangen-Nürnberg Loschgestrasse 15 D-91054 Erlangen Germany

References

  1. Tschöp M, Smiley DL, Heiman ML. Ghrelin induces adiposity in rodents. Nature 2000; 407: 908–913[CrossRef][ISI][Medline]
  2. Haqq AM, Farooqi IS, O’Rahilly S et al. Serum ghrelin levels are inversely correlated with body mass index, age, and insulin concentrations in normal children and are markedly increased in Prader-Willi syndrome. J Clin Endocrinol Metab 2003; 88: 174–178[Abstract/Free Full Text]
  3. Bellone S, Rapa A, Vivenza D et al. Circulating ghrelin levels as function of gender, pubertal status and adiposity in childhood. J Endocrinol Invest 2002; 25: RC13–15[ISI][Medline]
  4. Yoshimoto A, Mori K, Sugawara A et al. Plasma ghrelin and desacyl ghrelin concentrations in renal failure. J Am Soc Nephrol 2002; 13: 2748–2752[Abstract/Free Full Text]
  5. Gröschl M, Wagner R, Dötsch J, Rascher W, Rauh M. Preanalytical influences on the measurement of ghrelin. Clin Chem 2002; 48: 1114–1116[Free Full Text]




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