Octreotide, but not bromocriptine, increases circulating insulin-like growth factor binding protein 1 levels in acromegaly.
Twenty-three patients with active acromegaly underwent serum sampling for growth hormone (GH), insulin and insulin-like growth factor binding protein 1 (IGFBP-1) after placebo or single doses of octreotide or bromocriptine. Integrated 24-h serum GH levels decreased by 90% after octreotide and 49% after bromocriptine. A statistically significant correlation between the course of GH levels after octreotide and bromocriptine was observed (p < 0.001). Octreotide, but not bromocriptine, induced a significant increase in integrated 24-h serum IGFBP-1 levels to 37.4 times the baseline values. Bromocriptine caused a non-significant increase in integrated 24-h serum IGFBP-1 levels, which argues against a direct regulatory effect of GH on IGFBP-1 production in acromegaly. In conclusion, octreotide induces in acromegaly the production of IGFBP-1, which occurs independently of the number of somatostatin receptors on the GH-secreting pituitary adenoma. The supposed inhibitory effect of IGFBP-1 on the biological effect of IGF-1 might result in an additional clinical benefit in acromegalic patients as compared to treatment directed at the pituitary level.
de Herder
W W
WW
Department of Internal Medicine III, Erasmus University, Rotterdam, The Netherlands.
Uitterlinden
P
P
van der Lely
A J
AJ
Hofland
L J
LJ
Lamberts
S W
SW
D000172:Acromegaly / Q000097:blood* / Q000188:drug therapy*; D000328:Adult; D000368:Aged; D001971:Bromocriptine / Q000627:therapeutic use*; D002352:Carrier Proteins / Q000097:blood*; D005260:Female; D006801:Humans; D018970:Insulin-Like Growth Factor Binding Protein 1; D008297:Male; D008875:Middle Aged; D015282:Octreotide / Q000627:therapeutic use*; D013002:Somatomedins / Q000378:metabolism
D002352:Carrier Proteins; D018970:Insulin-Like Growth Factor Binding Protein 1; D013002:Somatomedins; D001971:Bromocriptine; D015282:Octreotide