title: Effectiveness of adding dopamine agonist therapy to long-acting somatostatin analogues in the management of acromegaly.
abstract: BACKGROUND
  The excess mortality and morbidity associated with acromegaly are secondary to prolonged elevation of GH and IGF-I. Vigorous control of these biochemical parameters results in improved morbidity and mortality. Somatostatin analogues (SAs) allow adequate control of GH and IGF-I in approximately 65% of subjects, leaving a significant cohort uncontrolled. Dopamine agonists (DAs), a cheap alternative to SAs, allow control of GH and IGF-I in less than 20% of patients with acromegaly.
  
  
  OBJECTIVE
  To assess the effectiveness of adding DA therapy to SA in the biochemical control of acromegaly.
  
  
  METHODS
  One hundred and twenty cases from the Sheffield Acromegaly Register were reviewed; 24 (20%) did not require medical treatment following pituitary surgery alone; 16 (13%) had safe GH levels following surgery and radiotherapy; and 58 (48%) required medical treatment despite having had surgery, radiotherapy or both. The remaining 22 (18%) received only medical treatment.
  
  
  METHODS
  In nine subjects a DA (three bromocriptine, six cabergoline) was added to an SA to control active disease. GH day curves and IGF-I levels were compared before and after the addition of a DA to existing SA treatment. All were on stable maximum-dose treatment with an SA, with inadequate biochemical control prior to addition of DA therapy. Mean duration of treatment on a DA before biochemical assessments were made was 10.3 months. Six subjects had previously been treated with either transsphenoidal surgery, radiotherapy or both. In three subjects SA was the primary therapy.
  
  
  RESULTS
  All subjects exhibited a fall in median GH and IGF-I levels. Introduction of a DA resulted in a 36.1% reduction in median GH levels (8.3 vs 5.3 mIU/l; P = 0.008) on a GH day curve and a 35.2% reduction in IGF-I levels (387.2 vs 251.0 microg/l; P = 0.018). Only four subjects had elevated prolactin levels prior to the addition of a DA (>368 mIU/l).
  
  
  CONCLUSIONS
  Addition of DAs to SAs is of benefit in the biochemical control of acromegaly and should be considered in those inadequately controlled. Furthermore, the beneficial effects of DAs occur even when pre-treatment prolactin levels are within the normal range.
authors.affiliation: Division of Clinical Sciences North, University of Sheffield, Northern General Hospital, UK.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Selvarajah
authors.forename: Jonathan
authors.initials: J
authors.lastname: Webster
authors.forename: Richard
authors.initials: R
authors.lastname: Ross
authors.forename: John
authors.initials: J
authors.lastname: Newell-Price
mesh_terms: D000172:Acromegaly / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001971:Bromocriptine / Q000008:administration & dosage; D000077465:Cabergoline; D018491:Dopamine Agonists / Q000008:administration & dosage*; D004873:Ergolines / Q000008:administration & dosage; D005260:Female; D019382:Human Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis; D008297:Male; D008875:Middle Aged; D011388:Prolactin / Q000097:blood; D012189:Retrospective Studies; D013004:Somatostatin / Q000031:analogs & derivatives*
chemical_list: D018491:Dopamine Agonists; D004873:Ergolines; D019382:Human Growth Hormone; D001971:Bromocriptine; D013004:Somatostatin; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D000077465:Cabergoline