Comparison of the Efficacy of Oral and Intramuscular Vitamin D Therapy in Obese Children with Vitamin D Deficiency

Abstract Introduction: The efficacy of oral versus intramuscular (IM) vitamin D administration in obese children is debatable. The purpose of this study was to compare the efficacy of oral versus IM administration of a single dose of cholecalciferol (300,000 IU) in obese children with vitamin D deficiency. Methods In an open-label, randomized, and cross-sectional clinical study, 96 obese patients with vitamin D deficiency and body mass index (BMI) > + 2 standard deviation scores (SDS) for their age and gender were recruited. Sixty-one children received a single IM dose of cholecalciferol (300,000 IU), while 35 children received an oral single dose of cholecalciferol (300,000 IU). At the initial clinic visit, baseline serum calcium (Ca), phosphorus (PO4), alkaline phosphatase (ALP), parathyroid hormone (PTH), and 25-hydroxyvitamin D (25OHD) concentrations were measured. After 12 weeks, serum biochemical and hormone levels were determined. The study’s primary endpoint was a change in serum 25OHD hormone levels. Results There was no statistically significant difference between the IM and oral groups and baseline in the median 25OHD levels (8 (4) vs. 10.3 (1.8) ng/mL) and PTH levels (70 (28) vs. 68 (22) pg/ml). Compared to the oral group, the IM group showed a statistically significant increase in the 25OHD levels (IM Δ25OHD: 31 (10) vs. oral Δ25OHD: 20 (6.7) ng/ml, p < 0.01), while the PTH levels were significantly reduced from their baseline levels (IM ΔPTH: 53.2 (31.5) vs. oral ΔPTH: 37.4 (27.2) pg/ml, p < 0.01). Conclusion In obese children, a single IM dose of vitamin D (300,000 IU) had a greater bioavailability than a similar dose given orally. Supplementation of vitamin D (300,000 IU), either IM or orally, was found to normalize 25OHD levels in vitamin D deficient obese children.