[Overdose or hypersensitivity to vitamin D?]

Vitamin D intoxication with severe hypercalcemia is rare in the neonatal and infancy period. Through nine cases of hypercalcemia, secondary to taking 600,000 units of vitamin D (Sterogyl(®)), a review of vitamin D requirements and possible mechanisms of toxicity including hypersensitivity to this vitamin will be discussed. We report nine cases of babies admitted to our department between the ages of 25 and 105 days for treatment of severe dehydration. The pregnancies were normal, with no incidents at delivery. Clinical signs were dominated by weight loss, vomiting, and fever. Examination on admission revealed dehydration whose degree ranged from 8 to 15% with preserved diuresis and loss weight between 100 and 1100 g. Laboratory tests objectified hypercalcemia between 113 and 235mg/L, hypercalciuria (urinary calcium/creatinine mmol/mmol >0.5), and a low-level of parathyroid hormone. The vitamin D values in nine patients were toxic (344-749 nmol/L; normal >50 nmol/L; toxicity if >250 nmol/L). Abdominal ultrasound objectified renal nephrocalcinosis in seven patients. The DNA study, performed in eight patients, did not reveal a mutation of the vitamin D 24-hydroxylase gene (CYP24A1). The treatment consisted of intravenous rehydration with treatment of hypercalcemia (diuretics and corticosteroids). Serum calcium returned to the normal range within 4-50 days, with weight gain progressively over the following weeks. The follow-up (2 years for the oldest case) showed the persistence of images of nephrocalcinosis. Genetic susceptibility and metabolic differences appear to modulate the threshold of vitamin D toxicity. However, respect for recommended doses, recognized as safe in a large study population, reduces the risk of toxicity.