Assessment of vitamin D status and parathyroid hormone during a combined intervention for the treatment of childhood obesity

Abstract

BACKGROUND: Obesity is associated with vitamin D deficiency. The aim of this work is to analyze the changes in vitamin D status and PTH levels in a group of children with obesity receiving combined intervention program in order to get BMI status reduction. METHODS: Longitudinal study in 119 children with obesity, aged 9.1-13.9 years, included in a 1-year combined dietary-behavioral-physical activity intervention. Anthropometric measurements (weight, height, BMI and fat mass index) were registered every 3 months and blood testing (calcium, phosphorous, 25(OH)D and PTH) were collected at the beginning and after 12 months of follow-up. A control group was recruited (300 healthy children, aged 8.1-13.9 years). The criteria of the US Endocrine Society were used for the definition of hypovitaminosis D. RESULTS: Vitamin D deficiency was significantly higher in obesity group (31.1 vs. 14%). There was negative correlation between 25(OH)D and fat mass index (r = -0.361, p = 0.001). Patients with BMI reduction throughout combined intervention were 52 (43.7%). There was a significant increase in the prevalence of hypovitaminosis D in patients without BMI reduction at the end of follow-up, but in those patients with BMI reduction there was no changes of vitamin D status. CONCLUSIONS: Obesity increases the prevalence of suboptimal vitamin D status, and a BMI status reduction in children with obesity may be required to at least stabilize vitamin D status.