title: Severe hypernatraemia associated with growth hormone replacement therapy in a patient with septo-optic dysplasia.
abstract: BACKGROUND
  The anti-natriuretic properties of growth hormone (GH) are well established. Growth hormone deficiency (GHD) results in salt and water depletion and studies confirm that replacement leads to sodium and vasopressin-mediated water retention in patients with intact posterior pituitary function.
  
  
  METHODS
  We report the case of a 20-year-old male patient with septo-optic dysplasia, fixed cranial diabetes insipidus (DI) and an abnormal thirst threshold. With careful parental support, his sodium levels remained stable for many years on a fixed dose of DDAVP and a supervised fluid intake of 2.5 l/day. Several years after the original diagnosis, he was found to be ACTH deficient and following commencement of hydrocortisone replacement therapy became hypernatraemic. A new sodium homoeostasis was established with a higher dose of DDAVP. Subsequently, he developed symptoms typical of GHD and, after biochemical confirmation, GH replacement was commenced.
  
  
  RESULTS
  There was an immediate clinical improvement (increased alertness, improved concentration) but severe hypernatraemia developed (peak 169 mmol/l) necessitating revision of his desmopressin and fluid intake regimen.
  
  
  CONCLUSIONS
  Most GHD patients have intact posterior pituitary function. This case report highlights the powerful anti-natriuretic properties of GH. Endocrine physicians should be alert to this in patients with fixed DI and an abnormal thirst threshold.
authors.affiliation: Department of Endocrinology, St Bartholomew's Hospital, London, UK. shivanimisra@gmail.com
authors.forename: Shivani
authors.initials: S
authors.lastname: Misra
authors.forename: Linda Brown
authors.initials: LB
authors.lastname: Johnston
authors.forename: William Martyn
authors.initials: WM
authors.lastname: Drake
mesh_terms: D013006:Growth Hormone / Q000009:adverse effects* / Q000627:therapeutic use; D020249:Hormone Replacement Therapy / Q000009:adverse effects*; D006801:Humans; D006955:Hypernatremia / Q000139:chemically induced*; D008297:Male; D025962:Septo-Optic Dysplasia / Q000188:drug therapy*; D055815:Young Adult
chemical_list: D013006:Growth Hormone