ESPE Abstracts

Background: The serum 25-hydroxyvitamin D (25OHD) levels are known to be lower in obese children, probably due to sequestration of vitamin D in the adipose tissue. However, there is no consensus on the dose adjustment for vitamin D supplementation in obese children with vitamin D deficiency (VDD).

Aims: To compare the response to vitamin D replacement in normal weight vs overweight children with VDD, and to investigate the determinant for increment of 25OHD level (Δ25OHD) after vitamin D replacement.

Methods: Participants were 65 Korean children between 8 and 15 years of age diagnosed with VDD between December 2013 and February 2014. VDD was defined as serum 25OHD <20 ng/ml and vitamin D sufficiency as 25OHD ≥30 ng/ml. Overweight was defined as BMI ≥85th percentile (n=20), and normal weight as BMI 5th–84th percentile (n=45). All participants received vitamin D3 supplementation (2000 IU/day) for 8 weeks. The levels of 25OHD and biochemical parameters were measured before and after treatment. Body fat was measured by bioelectrical impedance analysis.

Results: After 8 weeks of treatment, 33.3% of overweight children and 68.9% of normal weight children attained vitamin D sufficiency (P=0.02). The Δ25OHD was higher in normal weight group than in overweight group (20.6±7.2 ng/ml vs 15.0±7.6 ng/ml, P=0.006). Calcium creatinine ratio was lower than 0.2 in all participants before and after vitamin D replacement. Body surface area (BSA) was the determinant of Δ25OHD (β=−0.644, P=0.034) in a regression model including age, gender, body fat, BSA, and being overweight (R²=0.219).

Conclusion: The response to vitamin D replacement seems to be influenced by the size of the body rather than adiposity. To achieve vitamin D sufficiency, dose adjustment for vitamin D supplementation is required according to the patient’s BSA.

Funding: This work was supported by the FNDnet research council.