Ghrelin levels in young children with Prader-Willi syndrome

Objective

To explore the hypothesis that high ghrelin levels contribute to obesity in Prader-Willi syndrome (PWS), we assessed whether the increased levels observed in older persons with PWS exist in very young children, before the onset of hyperphagia.

Study design

We measured ghrelin levels in nine children with PWS (17-60 months of age) and eight healthy control subjects of equivalent body mass index (BMI), age, and sex.

Results

PWS and control groups had equivalent BMI (16.8 ± 1.4 vs 16.1 ± 0.9 kg/m², respectively; P = .24), age (37.8 ± 15.4 vs 50.3 ± 17.7 months; P = .14), and sex. PWS and control groups also had equivalent fasting levels of total ghrelin (787 ± 242 vs 716 ± 135 pg/mL, respectively; P = .24), bioactive ghrelin (102 ± 35 vs 91 ± 23 pg/mL; P = .45), insulin, and glucose. Ghrelin correlated negatively with BMI among controls (r = −0.760, P = .029) but not PWS (r = 0.015, P = .97).

Conclusions

Children <5 years of age with PWS, who had not yet developed hyperphagia or excessive obesity, had normal ghrelin levels, in contrast with the hyperghrelinemia of older, hyperphagic people with PWS. It is possible that ghrelin levels increase suddenly before hyperphagia develops.

Abbreviations:  BMI, Body mass index , FISH, Fluorescence in situ hybridization , GH, Growth hormone , HOMA, Homeostasis Model Assessment , PWS, Prader-Willi syndrome , RIA, Radioimmunoassay , UPD, Uniparental disomy