Bone turnover is not influenced by serum 25-hydroxyvitamin D in pubertal healthy black and white children

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 D(3) 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 was 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.