[How I treat … vitamin D intoxication in a child with cystic fibrosis]

At least 80 % of persons with cystic fibrosis are pancreatic insufficient and benefit from daily supplementation with fat-soluble vitamins (ADEK). Magistral formulations offer ideal flexibility for prescriptions tailored to vitamin A, D and E blood levels. However, they expose to human errors, mainly leading to vitamin D intoxication whose clinical features are related to hypercalcaemia. Symptoms are mostly digestive (vomiting, constipation, abdominal pain …) and, less frequently, renal (nycturia …) complaints. When symptoms and/or serum calcium levels ≥ 14 mg/100 ml are present, prompt management is required. Besides interruption of supplementation, rapid intravenous hyperhydration (saline) is essential. Once hydration has been restored, and still under close biological supervision, a loop diuretic (furosemide) may be used but the drug of choice to achieve rapid normalization of blood calcium levels will often be intravenous pamidronate. Normalization of serum vitamin 25(OH)-D levels may take several months but the prognosis is very good. In Belgium, the very late reimbursement of a fixed combination of fat-soluble vitamins (Dekas®) meeting the standards of the pharmaceutical industry is expected to reduce the incidence of these intoxications, at the price, however, of less flexible prescription.