ESPE Abstracts

Background: Hypercalcaemia is caused by many different conditions. Vitamin D intoxication with severe hypercalcemia is rare in the neonatal and infancy period. Here we described a 4-month-old male with severe hypercalcemia secondary to taking oral 600 000 units of vitamin D. He was diagnosed vitamin D 24-hydroxylase gene (CYP24A1) mutation after evaluation.

Case presentatıon: He was admitted to our hospital with high serum calcium level (23 mg/dl). Serum vitamin D level was >250 ng/ml, parathyroid hormone level was 1.7 pg/ml. The treatment consisted of intravenous rehydration with treatment of hypercalcemia (diuretics and corticosteroids) at the beginning. Because serum calcium level decreased slowly, pamidronate treatment was added. Serum calcium returned to the normal range within 12 days, with weight gain progressively over the following weeks. Abdominal ultrasound objectified renal nephrocalcinosis.

Conclusion: Mutations in the CYP24A1 gene cause reduced serum 24.25(OH)₂D₃ to 25(OH)D₃ ratio (<0.02), elevated serum 1,25-dihydroxyvitamin D (1.25(OH)₂D₃), hypercalcemia, hypercalciuria and nephrolithiasis. This case might accepted vitamin D intoxication because of high vitamin D intake. But severe hypercalcemia should be remarkable for CYP24A1 gene mutation.