Reduced bone mineral density and increased bone turnover in prader-willi syndrome compared with controls matched for sex and body mass index—a cross-sectional study

Abstract

Objectives To study bone mineral status, body composition, and biochemical markers of bone turnover in Prader-Willi syndrome (PWS). Study design Eight subjects with PWS (three males, five females; mean age, 24 years [range 16-41]) were included. Each subject was compared with an age-, sex- and body mass index-matched control randomly drawn from the background population. Bone mineral density (BMD), lean body mass, and fat mass were measured. Plasma PINP, PIIINP, osteocalcin, total alkaline phosphatase, bone-specific alkaline phosphatase, C-terminal telopeptide of type I collagen, and urine cross-linked N-terminal telopeptide of type I collagen were measured as biochemical markers of bone and collagen turnover. Results The PWS patients had significantly lower whole-body BMD (mean ± SD, 1.020 ± 0.041 vs 1.237 ± 0.118 g/cm 2; 2p < .01) than controls due to lower bone mineral content (BMC: 2291 ± 607 vs 2825 ± 409 g; 2p = .02). Resorptive and formative bone markers were significantly elevated in patients compared with controls. Plasma testosterone was low in male patients (3.50 ± 4.97 vs 19.2 ± 8.78 nmol/L, 2p = .05), whereas no difference in plasma estradiol was present. Conclusions The patients had a low BMD due to a high bone turnover. This high turnover was probably linked to sex steroid deficiency.