The relationship between vitamin D and adolescents' parathyroid hormone and bone mineral density

Introduction: To detect the relationship between 25-hydroxy vitamin D (25(OH)D) and adolescents' parathyroid hormone (PTH) and bone mineral density (BMD). Material and methods: Two hundred adolescent girls were recruited for this cross-sectional comparative study. After detailed evaluation, a pelvic sonography was performed for the studied adolescents to rule out any pelvic pathology. Adolescents' blood samples were collected to measure the thyroid stimulating hormone, prolactin, glycosylated haemoglobin (HbA(1C)), PTH, and 25(OH)D. The studied adolescents' BMD and the T-score were evaluated at 2 anatomical sites. The studied adolescents were classified according to their serum 25(OH)D into 2 groups: a 25(OH)D-deficient group (study group; 25(OH)D < 20 ng/ml) and normal controls (25(OH)D > 30 ng/ml). Student's t -test was used for analysis of the studied adolescents' variables, and correlation analysis (Pearson`s correlation) was used to detect the relationship between 25(OH)D and adolescents' PTH and BMD. Results: The parathyroid hormone was statistically higher in the 25(OH)D-deficient group than in the normal controls (41.3 +/- 3.4 pg/ml vs. 21.1 +/- 2.8) (p = 0.02), and the BMD was statistically lower in the 25(OH)D-deficient group than in the normal controls (-1.25 +/- 0.5 vs. 0.3 +/- 0.4) (p = 0.01). The 25(OH)D had a significant negative correlation with the adolescents' PTH (r = -0.9175; p < 0.00001) and a significant positive correlation with the adolescents' BMD (r = 0.756; p < 0.00001). The parathyroid hormone had a significant negative correlation with the adolescents' BMD (r = -0.7006; p < 0.00001). Conclusions: The parathyroid hormone in this study had significant negative correlations with both 25(OH)D and BMD. The 25(OH)D had a significant positive correlation with the studied adolescents' BMD.