Population-based pediatric reference values for serum parathyroid hormone, vitamin D, calcium, and phosphate in Danish/North-European white children and adolescents.

INTRODUCTION: Parathyroid hormone (PTH) and vitamin D are essential hormones in bone metabolism, especially during pediatric growth. Vitamin D insufficiency is often asymptomatic and is prevalent in high-latitude countries. METHODS: In a Danish population-based cohort of 2211 6-18-year-olds, sex- and age-specific pediatric reference values for fasting concentrations of intact serum PTH, vitamin D (25-hydroxycholecalciferol, 25-OH-D), total calcium, and phosphate were generated in accordance with Clinical and Laboratory Standards Institute (CLSI) EP28-A3c guidelines. The effect of season on these biomarkers of bone metabolism was evaluated. RESULTS: In boys, PTH concentrations increased with age, while the vitamin D and phosphate concentrations decreased (all p < .001). In girls, a peak in PTH concentrations and a nadir in vitamin D concentrations were observed in the 10-14-year-olds (both p < .001). Calcium and phosphate decreased with age for both sexes (girls: both p < .001; boys calcium: p < .05, boys phosphate: p < .001). Vitamin D was 20% lower in winter than summer for both sexes (both p < .001). Individuals with vitamin D sufficiency (25-OH-D > 50 nmol/L) exhibited a 5% lower level of PTH compared to the whole sample population (p < .001). CONCLUSION: The concentrations of PTH, vitamin D, calcium, and phosphate vary during childhood and adolescence, and is dependent on sex and season. These factors should be considered when screening for and treating imbalances in bone metabolism.

Genetic Susceptibility for Childhood BMI has no Impact on Weight Loss Following Lifestyle Intervention in Danish Children.

OBJECTIVE: This study aimed to investigate the effect of a genetic risk score (GRS) comprising 15 single-nucleotide polymorphisms, previously shown to associate with childhood BMI, on the baseline cardiometabolic traits and the response to a lifestyle intervention in Danish children and adolescents. METHODS: Children and adolescents with overweight or obesity (n = 920) and a population-based control sample (n = 698) were recruited. Anthropometric and biochemical measures were obtained at baseline and in a subgroup of children and adolescents with overweight or obesity again after 6 to 24 months of lifestyle intervention (n = 754). The effects of the GRS were examined by multiple linear regressions using additive genetic models. RESULTS: At baseline, the GRS associated with BMI standard deviation score (SDS) both in children and adolescents with overweight or obesity (ß = 0.033 [SE = 0.01]; P = 0.001) and in the population-based sample (ß = 0.065 [SE = 0.02]; P = 0.001). No associations were observed for cardiometabolic traits. The GRS did not influence changes in BMI SDS or cardiometabolic traits following lifestyle intervention. CONCLUSIONS: A GRS for childhood BMI was associated with BMI SDS but not with other cardiometabolic traits in Danish children and adolescents. The GRS did not influence treatment response following lifestyle intervention.