Background: High plasma ghrelin levels have been reported in Prader-Willi syndrome (PWS). However, little is known about plasma ghrelin in these children during the first years of life characterized by a failure to thrive.

Objective: To investigate total plasma ghrelin levels in children with PWS and in controls from 2 months to 17 years.

Subjects and methods: Forty children with PWS (24 boys 16 girls, median age 3.6 years, median BMI Z-score 0.3) were compared to 84 controls (57 boys 27 girls median age 4.2 years median BMI Z-score 0.1) Children were then divided into 2 groups according to age and GH treatment.

Results: Median plasma ghrelin levels were significantly higher in children with PWS compared to controls at any age (568 vs. 173, p<0.0001) and decreased with age in both groups (p<0.0001). In the whole group of PWS, we found an inverse relationship between ghrelin and BMI Z-score, insulin, HOMA-IR, leptin and lean mass. Plasma ghrelin levels were higher in children with PWS than in controls, both in the youngest children below 3 years who were not receiving GH (771 vs. 233 p<0.0001) and in the children over 3 years all of whom were treated with GH (428 vs. 159 p<0.0001).

Conclusions: Plasma ghrelin levels in children with PWS are elevated at any age, including during the first years of life, thus preceding the development of obesity.