Abstract
Bone turnover markers (BTMs) are circulating or urinary byproducts of bone formation and resorption that provide a dynamic, near–real-time assessment of skeletal metabolism. In children and adolescents, BTMs are substantially higher than in adults because bone modeling and remodeling accompany rapid linear growth and pubertal maturation; concentrations may be several-fold (up to 5–20×) greater than adult levels, with distinct age-, sex-, and puberty-related trajectories. These physiological patterns complicate interpretation but also create opportunities: BTMs can act as proxies for growth velocity, pubertal timing, and early perturbations in bone health when imaging is limited by growth-related artifacts or concerns about repeated radiation exposure. This mini-review summarizes the major pediatric BTMs, including formation markers – procollagen type I N-terminal propeptide (P1NP), bone-specific alkaline phosphatase, and osteocalcin (OC) – and resorption markers – serum C-terminal telopeptide of type I collagen (β-CTX), urinary or serum N-terminal telopeptide, and tartrate-resistant acid phosphatase 5b (TRAP-5b). We discuss practical applications in pediatric endocrinology and metabolic bone disease (e.g., rickets, primary and secondary osteoporosis, and chronic inflammatory disorders), emphasizing monitoring of therapy response, adherence, and recovery of bone remodeling balance. Key limitations include high biological variability, strong diurnal/feeding effects (particularly for CTX), and assay nonharmonization, which necessitate standardized pre-analytical sampling and robust age-/sex-specific reference intervals. Recent research has strengthened pediatric reference interval datasets across populations and advanced plans to harmonize reference markers (P1NP and β-CTX) to improve comparability across studies and laboratories. Overall, BTMs are valuable adjuncts – when interpreted with developmental context and standardized sampling – to support pediatric bone health assessment and longitudinal management.