title: Hypophosphatasia in a child with widened anterior fontanelle: lessons learned from late diagnosis and incorrect treatment.
abstract: Hypophosphatasia is characterized by deficiency of serum alkaline phosphatase with defective bone and teeth mineralization. We report on an 11-month-old boy who developed a complex clinical picture characterized by bulging anterior fontanelle, growth failure, nephrocalcinosis and impaired bone mineralization during high-dose calcium and vitamin D supplementation. This therapy had been started 5 months earlier for a presumed diagnosis of nutritional rickets established on the grounds of isolated widened anterior fontanelle. However, laboratory investigations revealed reduced alkaline phosphatase levels associated with hypercalcemia, hypercalciuria, low PTH and normal 25-hydroxy vitamin D levels. Genetic testing detected a compound heterozygote for the novel mutation (c.262G>A) and the described mutation (c.920C>T) in the ALPL gene.
  
  
  CONCLUSIONS
  High calcium and vitamin D supplementation should not be started in the presence of isolated signs of nutritional rickets without assessing calcium-phosphate metabolism. In fact, in rare bone-mineralizing disorders, this combined therapy might induce severe clinical complications.
authors.affiliation: Department of Paediatrics, University Hospital of Chieti, Chieti, Italy. amohn@unich.it
authors.forename: Angelika
authors.initials: A
authors.lastname: Mohn
authors.forename: Chiara
authors.initials: C
authors.lastname: De Leonibus
authors.forename: Tommaso
authors.initials: T
authors.lastname: de Giorgis
authors.forename: Etienne
authors.initials: E
authors.lastname: Mornet
authors.forename: Francesco
authors.initials: F
authors.lastname: Chiarelli
mesh_terms: D000469:Alkaline Phosphatase / Q000172:deficiency* / Q000235:genetics; D002118:Calcium / Q000627:therapeutic use; D055762:Cranial Fontanelles / Q000473:pathology*; D057210:Delayed Diagnosis; D003951:Diagnostic Errors; D006801:Humans; D007014:Hypophosphatasia / Q000175:diagnosis*; D007223:Infant; D008297:Male; D008508:Medication Errors; D009154:Mutation / Q000235:genetics; D012279:Rickets / Q000175:diagnosis* / Q000188:drug therapy; D014807:Vitamin D / Q000627:therapeutic use
chemical_list: D014807:Vitamin D; C548267:ALPL protein, human; D000469:Alkaline Phosphatase; D002118:Calcium