title: A Pediatric Patient with a CYP24A1 Mutation: Four Years of Clinical, Biochemical, and Imaging Follow-Up.
abstract: BACKGROUND
  A female infant was admitted to hospital due to failure to thrive. She presented hypercalcemia (4.09 mmol/L, normal range: 2.2-2.65 mmol/L), high 25-hydroxyvitamin D (283 nmol/L, normal range: 75-250 nmol/L), 1,25-dihydroxyvitamin D in the upper normal range, and low parathyroid hormone. Vitamin D intoxication was suspected. The patient had received routine rickets prophylaxis.
  
  
  METHODS
  Williams-Beuren syndrome was genetically excluded. Sequencing of CYP24A1 showed 2 mutations: c.443T>C and c.1186C>T.
  
  
  RESULTS
  The patient's clinical status improved after intravenous rehydration, cessation of supplementation, and on a low-calcium diet. 25-Hydroxyvitamin D concentrations normalized within days, while 1,25-dihydroxyvitamin D remained in the upper normal range. We also investigated our patient's bone health.
  
  
  CONCLUSIONS
  The patient was hospitalized initially on suspicion of vitamin D intoxication but proved to be a case of compound heterozygosity. Data on the long-term clinical and biochemical evolution of patients with idiopathic infantile hypercalcemia are sparse. Our follow-up showed seasonal variations of vitamin D and calcium parameters, with no influence on kidney function or bone health for the investigated period.
authors: University Clinic for Pediatrics and Adolescent Medicine, Medical University of Vienna, Vienna, Austria.
authors: Diana-Alexandra
authors: DA
authors: Ertl
authors: Adalbert
authors: A
authors: Raimann
authors: Dagmar
authors: D
authors: Csaicsich
authors: Janina M
authors: JM
authors: Patsch
authors: Franco
authors: F
authors: Laccone
authors: Gabriele
authors: G
authors: Haeusler
mesh_terms: D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006934:Hypercalcemia / Q000235:genetics* / Q000628:therapy*; D007223:Infant; D017354:Point Mutation; D012279:Rickets / Q000235:genetics* / Q000628:therapy*; D065668:Vitamin D3 24-Hydroxylase / Q000235:genetics* / Q000378:metabolism
chemical_list: C585549:CYP24A1 protein, human; D065668:Vitamin D3 24-Hydroxylase