C. M. Gordon1, K. DePeter*2, E. Grace*2, S. J. Emans*2. 1Endocrinology & Adolescent Med., Children’s Hospital, Boston, MA, USA, 2Adolescent Medicine, Children’s Hospital, Boston, MA, USA.

Vitamin D is essential for optimal bone accretion during adolescence. In a clinic sample of healthy adolescent girls and boys, we sought to determine the prevalence of hypovitaminosis D. We also examined whether the prevalence differed by gender, season or ethnicity, and examined anthropometric and lifestyle predictors of serum levels of 25-hydroxyvitamin D (25D). 282 adolescents (185 girls and 97 boys) who presented to an outpatient adolescent medicine practice in Boston, MA were evaluated at the time of a routine physical examination. Serum levels of 25D, parathyroid hormone (PTH), calcium, phosphorus and magnesium were obtained, and activity and nutritional questionnaires completed. The prevalence of hypovitaminosis D (<15 ng/ml) was 20% for the cohort. The problem was more prevalent in girls (22%) than boys (15%), and more prevalent in African – American (30%) than Asian (17%), Hispanic (18%), or White (2%) teenagers. There was a seasonal variation noted, with a prevalence of 9% during summer (July – Sept.) and 36% during winter (Jan.- March). The mean winter 25D level was significantly lower than that during summer (10.7 +/- 2.4 vs. 27.7 +/- 10.1 ng/ml, p<0.001), and PTH levels were higher (54.6 +/- 26.7 vs. 43.7 +/-19.9 pg/ml, p=0.006). There was a significant negative correlation between serum 25D and PTH (r= -0.27, p<0.001). There was a modest, but significant positive correlation between 25D levels and reported consumption of vitamins(r= 0.15, p=0.012) and calcium supplements (r= 0.15, p=0.013), and a negative correlation between 25D and both weight (r= -0.18, p=0.003) and body mass index (r= -0.17, p=0.004). There were no significant differences among boys and girls with respect to use of multivitamins or calcium supplements, but daily milk consumption was higher in the boys than girls (2.8 +/- 2.2 vs. 1.6 +/- 1.1 cups, p<0.001). Both the boys and girls with hypovitaminosis D reported significantly lower milk consumption than those who were replete (1.4 +/- 1.1 vs. 2.2 +/- 2.0 cups, p=0.039). Hypovitaminosis D occurred in 20% of otherwise healthy teenagers in a clinic sample from Boston, a city of northern latitude. The problem was more prevalent in girls than boys, and most prevalent among adolescents of African-American descent. These findings suggest that hypovitaminosis D is a significant problem among teenagers. Adolescent providers should take note of these findings, both of the high prevalence of this health problem and suboptimal nutritional practices, especially among girls and adolescents of certain ethnicities.