Endocrine Abstracts

Introduction: Prevalence of vitamin D deficiency is well recognised and public awareness is being raised to encourage intake of vitamin D supplements. Optimal serum concentration of 25OHD for bone and general health has not been established. Desirable serum concentration of 25OHD had been proposed as >75 nmol/l and levels above 500 nmol/l are deemed toxic. Guidance is available on tolerable upper limit of vitamin D intake by US Institute of Medicine.

Case report: A 4-year-old boy presented with a history of vomiting, polydipsia, polyuria, weight loss, and worsening constipation. He had been taking a number of holistic medications including vitamin D and calcium supplements to help with his autism. Corrected calcium at presentation was 4.08 mmol/l, with low PTH of 0.6 pmol/l and undetectably high 25OH vitamin D level on the standard assay. He was initially managed with hyperhydration, calcitonin, and furosemide. Calcium level dropped to 3.15 mmol/l, however, there was a rebound rise in calcium levels and he was treated with pamidronate infusions. After 12 days of treatment, calcium level came down to 2.18 mmol/l. Results obtained by diluting initial blood sample revealed a very high 25OH vitamin D level of 1890 nmol/l. Further investigations revealed a normal MRI brain and mild nephrocalcinosis on USS of kidneys.

On further exploration, we discovered that he was prescribed one drop a day of concentrated solution of colecalciferol containing 2000 IU/drop but the child was being given at least 1 ml a day for 4 months, which amounts to 40 000 IU/day.

Conclusion: Though vitamin D toxicity is a rare occurrence, it is mainly due to inadvertent use of very high doses of vitamin D. When prescribing concentrated solutions, the dosage and risks should be carefully explained.