title: The sensitivity of growth hormone secretion to medical treatment in acromegalic patients: influence of age and sex.
abstract: OBJECTIVE
  We investigated the relationship between age, sex, pituitary tumour volume, serum GH, PRL and IGF-I levels with the responsiveness of GH to TRH, bromocriptine and octreotide in patients with acromegaly.
  
  
  METHODS
  We performed a retrospective study. Correlations were determined between all variables using univariate regression analysis.
  
  
  METHODS
  One hundred previously untreated acromegalic patients were studied (60 males (age 23-76; mean 49 years) and 40 females (age 25-83; mean 51 years)).
  
  
  METHODS
  We studied tumour volume, fasting morning circulating levels of GH, PRL and IGF-I, mean 24-hour circulating GH levels and the acute GH responses to TRH, bromocriptine and octreotide.
  
  
  RESULTS
  Tumour size was related to serum and mean 24-hour GH levels, but not to IGF-I. Circulating IGF-I and GH levels were related only for the group of patients whose fasting and unsuppressed GH level was 80 mU/l (40 micrograms/l) or less. Older patients tended to have lower circulating GH and IGF-I levels. There was a close similarity in the responsiveness of tumorous GH secretion to TRH, bromocriptine and octreotide. An elevated serum PRL level predicted a stronger inhibitory response of bromocriptine on GH. The sensitivity of GH release to octreotide was highest in elderly (especially male) acromegalics, as well as in patients with lower IGF-I levels.
  
  
  CONCLUSIONS
  Hormone secretion by GH secreting pituitary tumours, as well as circulating IGF-I levels, tend to be lower in elderly patients. These tumours are more sensitive to octreotide, especially in elderly male patients. This suggests that octreotide might be used especially successfully as a primary medical therapy in elderly, male acromegalics.
authors.affiliation: Department of Medicine, Erasmus University, Rotterdam, The Netherlands.
authors.forename: A J
authors.initials: AJ
authors.lastname: van der Lely
authors.forename: A G
authors.initials: AG
authors.lastname: Harris
authors.forename: S W
authors.initials: SW
authors.lastname: Lamberts
mesh_terms: D000172:Acromegaly / Q000188:drug therapy* / Q000378:metabolism; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001971:Bromocriptine / Q000627:therapeutic use; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*; D010911:Pituitary Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D011388:Prolactin / Q000097:blood; D012737:Sex Factors; D013973:Thyrotropin-Releasing Hormone
chemical_list: D001971:Bromocriptine; D013973:Thyrotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D013006:Growth Hormone; D015282:Octreotide