title: The nadir growth hormone after an octreotide test dose predicts the long-term efficacy of somatostatin analogue therapy in acromegaly.
abstract: OBJECTIVE
  In the treatment of acromegaly, a 'test dose' of octreotide is recommended prior to the use of depot somatostatin analogue (SSA) therapy. However, there remains no consensus regarding the criteria that predict a response to treatment. The ability to select patients who may benefit most from medical therapy is potentially of great value in clinical practice. The aim of the study was to determine the predictive value of both the nadir GH and the mean GH following an octreotide test dose in identifying patients who subsequently achieved disease remission with depot SSA therapy. Remission was defined as a mean GH < 5 mU/l (< 2 microg/l).
  
  
  METHODS
  Retrospective case-control study.
  
  
  METHODS
  A group of 41 patients with acromegaly underwent an octreotide test dose where GH was measured hourly for a total of 6 h following an injection of octreotide 50 microg subcutaneously. Nadir GH and mean GH following the octreotide test dose were determined. Thirty-three patients were subsequently treated with depot SSA therapy and mean GH and IGF-I levels were determined at follow-up.
  
  
  RESULTS
  The nadir GH demonstrated superior predictive power to that of mean GH across a range of GH cut-off values. A nadir GH < 5 mU/l demonstrated 80% sensitivity and 83% specificity in predicting remission with depot SSA therapy. A nadir GH < 10 mU/l demonstrated 100% sensitivity and 56% specificity.
  
  
  CONCLUSIONS
  The nadir GH following an octreotide test dose is a useful predictive marker of achieving disease remission with depot SSA therapy used as either a primary or an adjuvant agent.
authors.affiliation: Department of Endocrinology, King's College Hospital, London, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Gilbert
authors.forename: J P
authors.initials: JP
authors.lastname: Miell
authors.forename: S M
authors.initials: SM
authors.lastname: Chambers
authors.forename: A M
authors.initials: AM
authors.lastname: McGregor
authors.forename: S J B
authors.initials: SJ
authors.lastname: Aylwin
mesh_terms: D000172:Acromegaly / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D000328:Adult; D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use; D016022:Case-Control Studies; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
chemical_list: D018931:Antineoplastic Agents, Hormonal; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D015282:Octreotide