title: Cinacalcet monotherapy in neonatal severe hyperparathyroidism: a case study and review.
abstract: BACKGROUND
  Neonatal severe hyperparathyroidism (NSHPT) is a severe form of familial hypocalciuric hypercalcemia characterized by severe hypercalcemia and skeletal demineralization. In most cases, NSHPT is due to biallelic loss-of-function mutations in the CASR gene encoding the calcium-sensing receptor (CaSR), but some patients have heterozygous mutations. Conventional treatment consists of iv saline, bisphosphonates, and parathyroidectomy.
  
  
  OBJECTIVE
  The aim of this project was to characterize the molecular basis for NSHPT in an affected newborn and to describe the response to monotherapy with cinacalcet.
  
  
  METHODS
  Clinical and biochemical features were monitored as cinacalcet therapy was initiated and maintained. Genomic DNA was obtained from the proband and parents. The CASR gene was amplified by PCR and sequenced directly.
  
  
  RESULTS
  The patient was a full-term male who developed hypotonia and respiratory failure soon after birth. He was found to have multiple fractures and diffuse bone demineralization, with a marked elevation in serum ionized calcium (1.99 mmol/L) and elevated serum levels of intact PTH (1154 pg/mL); serum 25-hydroxyvitamin D was low, and fractional excretion of calcium was reduced. The serum calcium level was not reduced by iv saline infusion. Based on an extensive family history of autosomal dominant hypercalcemia, a diagnosis of NSHPT was made, and cinacalcet therapy was initiated with a robust and durable effect. Molecular studies revealed a heterozygous R185Q missense mutation in the CASR in the patient and his father, whereas normal sequences for the CASR gene were present in the patient's mother.
  
  
  CONCLUSIONS
  We describe the first use of cinacalcet as monotherapy for severe hypercalcemia in a newborn with NSHPT. The rapid and durable response to cinacalcet suggests that a trial of calcimimetic therapy should be considered early in the course of NSHPT.
authors.affiliation: Division of Endocrinology and Diabetes (A.W.G., M.A.L.), and Department of Pharmacy Services (H.M.M.), The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104; and Department of Pediatrics (A.W.G., M.A.L.), University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104.
authors.forename: Anthony W
authors.initials: AW
authors.lastname: Gannon
authors.forename: Heather M
authors.initials: HM
authors.lastname: Monk
authors.forename: Michael A
authors.initials: MA
authors.lastname: Levine
mesh_terms: D000069449:Cinacalcet; D006801:Humans; D006961:Hyperparathyroidism / Q000151:congenital / Q000188:drug therapy* / Q000235:genetics; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000188:drug therapy*; D008297:Male; D009281:Naphthalenes / Q000627:therapeutic use*; D044169:Receptors, Calcium-Sensing / Q000235:genetics; D012720:Severity of Illness Index; D016896:Treatment Outcome
chemical_list: C095550:CASR protein, human; D009281:Naphthalenes; D044169:Receptors, Calcium-Sensing; D000069449:Cinacalcet