Serum PTHrP level as a biomarker in assessing skeletal maturation during circumpubertal development

IntroductionMany investigators have studied the cellular organization and the local and systemic factors regulating endochondral bone growth in the growth plate and condylar cartilage. Parathyroid hormone-related protein (PTHrP) and Indian hedgehog protein have been reported to regulate multiple steps during such skeletal morphogenesis. The aims of this study were to quantify serum PTHrP levels at 6 cervical vertebral stages and to correlate serum PTHrP levels to the 6 skeletal maturation stages for use as a biologic indicator of skeletal maturation.MethodsMean serum PTHrP levels were measured in 90 subjects categorized into 6 cervical vertebral stages.ResultsMean serum PTHrP levels were significantly higher in the late pubertal stages than in the early pubertal stages. Pearson correlation showed that serum PTHrP levels had a positive correlation with cervical vertebral maturation stages from the prepubertal to the late pubertal stages, and a negative correlation from the late pubertal to the postpubertal stages.ConclusionsPeak serum PTHrP levels do not correlate with early pubertal stages characterized by maximum growth increments. Hence, the validity of using serum PTHrP levels to predict peak growth velocity is questionable.