title: Poor responses to a test dose of subcutaneous octreotide predict the need for adjuvant therapy to achieve 'safe' growth hormone levels.
abstract: OBJECTIVE
  Somatostatin analogues are an established treatment in acromegaly. This study was designed to evaluate whether the acute serum growth hormone (GH) response to a test dose of octreotide in acromegaly predicts longer-term response to the drug at 3 years.
  
  
  METHODS
  In 23 patients, GH responses across 8 h to a subcutaneous test dose (50 microg) of octreotide were compared with GH levels after 3 years of therapy. The majority had pituitary surgery as primary therapy and at 3 years were receiving at least 600 microg octreotide daily subcutaneously or 20 mg LAR monthly intramuscularly.
  
  
  RESULTS
  Seven had a test day GH Nadir of 5 mU/l or less of whom 4 achieved GH < 5 mU/l at 3 years. Sixteen had a test day nadir GH of 10 mU/l or less and of these 8 achieved GH < 5 mU/l at 3 years. Seven of the 23 had a GH Nadir >10 mU/l and of these 3 had achieved GH <5 mU/l at 3 years. However all of these 3 had received external pituitary irradiation within 4 years of the 3 year assessment, as compared with 3 of the <5 mU/l nadir group and 5 of the <10 mU/l nadir group.
  
  
  CONCLUSIONS
  In patients on optimal long-term doses of octreotide for acromegaly, absence of a nadir GH <10 mU/l in the 8 h after a test dose was associated with failure to achieve GH levels associated with a normal life expectancy (5 mU/l or less) unless adjunctive external pituitary irradiation was given. As well as testing tolerability a test dose of octreotide may help in determining which patients should be offered early external pituitary irradiation or therapy with a GH receptor antagonist if surgery has failed to achieve 'safe' GH levels.
authors.affiliation: Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK.
authors.forename: J R
authors.initials: JR
authors.lastname: Lindsay
authors.affiliation: Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK.
authors.forename: E M
authors.initials: EM
authors.lastname: McConnell
authors.affiliation: Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK.
authors.forename: S J
authors.initials: SJ
authors.lastname: Hunter
authors.affiliation: Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK.
authors.forename: D R
authors.initials: DR
authors.lastname: McCance
authors.affiliation: Regional Endocrine Laboratory, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK.
authors.forename: B
authors.initials: B
authors.lastname: Sheridan
authors.affiliation: Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, UK. ab.atkinson@royalhospitals.n-i.nhs.uk.|Regional Centre for Endocrinology and Diabetes, Royal Victoria Hospital, Grosvenor Rd, Belfast, BT12 6BA, UK. ab.atkinson@royalhospitals.n-i.nhs.uk.
authors.forename: A B
authors.initials: AB
authors.lastname: Atkinson
mesh_terms: D000172:Acromegaly / Q000097:blood / Q000188:drug therapy* / Q000532:radiotherapy / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D004305:Dose-Response Relationship, Drug; D005260:Female; D019382:Human Growth Hormone / Q000097:blood*; D006801:Humans; D007273:Injections, Intramuscular; D007279:Injections, Subcutaneous; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000008:administration & dosage* / Q000627:therapeutic use*; D010902:Pituitary Gland / Q000187:drug effects / Q000528:radiation effects / Q000601:surgery; D013997:Time Factors
chemical_list: D019382:Human Growth Hormone; D007334:Insulin-Like Growth Factor I; D015282:Octreotide