Bone metabolism markers and ghrelin in boys at different stages of sexual maturity

Aim: To examine the relationship of the markers of bone formation (procollagen type I N-terminal propeptide [PINP]) and bone resorption (type I carboxyterminal telopeptide [ICTP]) with bone mineral content (BMC), bone mineral density (BMD), ghrelin and testosterone in boys during puberty. Methods: Sixty boys were divided in three groups (20 boys in each) based on the pubertal stage (G1, I; G2-G3, II; G4-G5, III). Fasting PINP, ICTP, ghrelin and testosterone were measured. Total body BMD, lumbar BMD, lumbar apparent volumetric BMD (BMAD) and BMC were measured by DXA. Results: PINP and ICTP values peaked at the beginning of puberty (Group II). Ghrelin was lower in Groups II and III compared to less mature boys. PINP and ICTP correlated with each other and were associated with lumbar BMAD in total group of boys. Relationships of PINP and ICTP with total BMD, total BMC and lumbar spine BMD in Group I were observed. PINP and ICTP were also correlated with testosterone in Group II and with lumbar spine BMAD in Group III. Conclusion: These data suggest that testosterone stimulates PINP and ICTP in early puberty, while ghrelin has no direct influence on bone turnover markers in boys at different stages of puberty.