Bone Turnover is not Influenced by Serum 25-Hydroxyvitamin D in Pubertal Healthy Black and White Children

Abstract

Low serum 25-hydroxyvitamin D [25(OH)D] is common in healthy children particularly in blacks. However, serum 25(OH)D concentrations for optimal bone turnover in children is unknown and few data exist that describe effects of increasing serum 25(OH)D on bone turnover markers during puberty. The purpose of this study was to determine the relationships between serum 25(OH)D and changes in serum 25(OH)D and bone turnover in white and black pubertal adolescents. Bone turnover markers were measured in 318 healthy boys and girls from Georgia (34°N) and Indiana (40°N) who participated in a study of oral vitamin D3 supplementation (0 to 4000 IU/d). Serum 25(OH)D, osteocalcin, bone alkaline phosphatase, and urine N-telopeptide cross-links were measured at baseline and 12 weeks. Relationships among baseline 25(OH)D and bone biomarkers, and between changes over 12 weeks were determined and tested for effects of race, sex, latitude, and baseline 25(OH)D. Median 25(OH)D was 27.6 ng/mL (n=318, range 10.1–46.0 ng/mL) at baseline and 34.5 ng/mL (n=302, range 9.7–95.1 ng/mL) at 12 weeks. Neither baseline nor change in 25(OH)D over 12 weeks were associated with bone turnover. The lack of association was not affected by race, sex, latitude, or baseline serum 25(OH)D. Serum 25(OH)D in the range of 10-46 ng/mL appears to be sufficient for normal bone turnover in healthy black and white pubertal adolescents.