Bone Abstracts

Objectives: Guidelines for treatment of vitamin D deficiency (VDD) vary. We aimed to review the range of treatment regimens for VDD used locally and variation in responses.

Methods: We conducted a retrospective review of the records of consecutive patients referred to a Children’s Bone Disease Service with a putative diagnosis of VDD over a 14-month period. Data collected includes vitamin D type used, dose and duration of treatment, and pre- and post serum 25-hydroxy vitamin D (25OHD). Cases were excluded if these data were missing. Weight was used to calculate total dose of vitamin D per kg administered. In the absence of a contemporary weight, subjects were assumed to have mean weight for age. Presence of rickets, radiographic reports, history of fracture and adverse events were collected.

Results: From 66 consecutive subjects, 29 had pre- and post-treatment 25OHD concentrations and a confirmed serum 25OHD <25 nmol/l. Demographics – 18/29 male; 12/29 South Asian, 7/29 Black African, and 4/29 White British. 13/29 had radiographs looking for signs of rickets. In 2/13 rachitic features were identified. In both cases repeat radiographs confirmed resolution with treatment. 4/29 had ever suffered fractures. Cholecalciferol treatment was variably instituted by primary or secondary care physicians. Daily doses ranged 3000–10 000 U (median 6000); duration 4–12 weeks (median 6). 2/29 subjects received two doses of 100 000 U each. Estimated total dose/kg ranged 3400–35 000 U/kg (mean 13 500, S.D. 7400). The increase in serum 25OHD correlated with estimated total dose/kg (R²=29%, P=0.003). 2/29 remained vitamin D insufficient (34 and 45 nmol/l). 4/29 subjects had an increase in 25OHD >200 nmol/l. These were all under 18 months of age and received estimated total doses 11 000–35 000 U/kg over 4–12 weeks. There were no recorded adverse effects.

Conclusion: We found that commonly used regimens for treatment of VDD were effective in raising 25OHD to >50 nmol/l with no evidence of harm. This study is limited by its retrospective character, small size, incomplete data and potential bias regarding subject selection. However, there is variability in response to vitamin D treatment and we believe that clinicians should consider the weight-related total dose, particularly in younger children.