The End of the Apposition Period in Peak Bone Mass and Bone Remodeling Markers

ZENI SN, CASCO C, MASTAGLIA SR, SOMOZA J, DEFERRARI JM, SEIJO M, OLIVERI B

Philadelphia, Pennsylvania, USA

Congreso; Twneti- Eighth Annual Meeting of the American Society for Bone and Mineral Research; 2006

The American Society for Bone and Mineral Research

Different cross-sectional studies suggest that peak bone mass is reached between 17 and 35 years of age. Adequate bone apposition is essential for optimal skeleton growth and may be evaluated by biochemical bone turnover markers in different periods: bone collagen synthesis, its maturation and matrix mineralization, and by bone resorption markers. Therefore adequate reference values for each age are critical. Our objectives were 1) to establish reference values in healthy subjects of both sexes, divided into decades between 20 and 49 years of age 2) to determine the end of bone apposition through biochemical bone markers. A total of 126 subjects (61 men and 65 premenopausal women without interventions affecting bone and mineral metabolism and with serum calcium, phosphorus, and creatinine in the normal range were finally included. Fasting serum (8-10:30 am) was evaluated for C-terminal cross-linking telopeptide of type I collagen (B-CTX), collagen type I propeptide (P1NP) and osteocalcin (BGP) by Elecsys Roche (intra and inter-assay CV were 1.6 and 6.1%, and CV 6.9 and 2.9%, respectively) and bone alkaline phosphate (BAL) by precipitation (intra and inter-assay CV were 1.3 and 8.0 %, respectively). The biochemical parameters of the 126 subjects were analyzed by comparing by decades(20-29; 30-39; 40-49). We observed that BGP(ng/ml), PINP(ng/L), and CTX(ng/L) levels were greater in the decade 20-29 (27.8 ±9.8, 71.5 ± 24.1, 488±180 respectively) than in the decade 30-39 (20.4± 7.5, 50.7± 20.8, 318± 139),(p<0.001) and in the decade 40-49 (21.9±8.7, 50.5±20.2,329±165),(p<0.01 to p<0.001) respectively. No differences were observed in BAL among the tree decades (67.8±8.9, 66.7±13.4 and 68.0±13.6). In comparison to women men showed higher values of CTX in the 20-29 decade (p<0.03) and higher values of CTX, FAO, P1NP and BGP in decade 40-49 (p<0.02). We found a positive correlation between the levels of CTX and BGP (r= 0.6, p<0.001), BGP and BAL (r= 0.35, p<0.001), CTX and FAO (r=-0.3, p<0.02), P1NP and BGP(r=0.7, p<0.001), P1NP and BAL (r=0.3, p<0.006) and P1NP and CTX (r=0.6, p<0.001). We conclude that the speed of bone remodeling decreases after the third decade, suggesting the end of the apposition period of peak bone mass. No significant differences were observed between markers of bone collagen synthesis and maturation. BAL showed no differences over the decades.