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 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 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.

► Trial of vitamin D supplements on biomarkers of bone turnover in pubertal children.
► Black children had higher bone turnover and lower serum 25 (OH) D than whites.
► No association between bone turnover markers and basal winter serum 25(OH)D level.
► Increasing serum 25(OH)D with vitamin D over 12 weeks did not affect bone turnover.
► Serum 25(OH)D 10–46 ng/mL range maintains normal bone turnover at peak bone growth.