Plasma insulin-like growth factor-I/somatomedin-C in acromegaly: correlation with the degree of growth hormone hypersecretion

J Clin Endocrinol Metab. 1988 Jul;67(1):69-73. doi: 10.1210/jcem-67-1-69.

Abstract

We measured plasma insulin-like growth factor I/somatomedin-C (IGF-I/SmC) concentrations and mean 24-h GH secretion serially before and during therapy with the long-acting somatostatin analog SMS 201-995 in 21 patients with acromegaly. When mean plasma GH was elevated above 12.0 +/- 0.6 (+/- SE) micrograms/L, plasma IGF-I/SmC concentrations were uniformly high, but a decline of mean plasma GH below this value was accompanied by a linear decrease in IGF-I/SmC concentrations (r = 0.89; P less than 0.001). Even mildly abnormal mean GH concentrations (greater than 4.6 but less than 10 micrograms/L) were accompanied by high plasma IGF-I/SmC values. The log dose-response interrelation between mean 24-h plasma GH and IGF-I/SmC concentrations was linear (r = 0.86; P less than 0.001). We conclude that 1) an excellent log dose-response correlation between mean 24-h plasma GH and IGF-I/SmC concentrations is present in patients with acromegaly; 2) normalization of plasma IGF-I/SmC occurs only in patients with mean daily GH output within the normal range; and 3) determination of plasma IGF-I/SmC is an accurate indicator of normalcy of GH secretion and should be used in the diagnosis of active acromegaly as well as in monitoring the progress of therapy.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acromegaly / blood*
  • Acromegaly / drug therapy
  • Adolescent
  • Adult
  • Aged
  • Circadian Rhythm / drug effects
  • Delayed-Action Preparations
  • Dose-Response Relationship, Drug
  • Female
  • Growth Hormone / blood
  • Growth Hormone / metabolism*
  • Humans
  • Insulin-Like Growth Factor I / blood*
  • Male
  • Middle Aged
  • Octreotide
  • Secretory Rate / drug effects
  • Somatomedins / blood*
  • Somatostatin / analogs & derivatives
  • Somatostatin / therapeutic use

Substances

  • Delayed-Action Preparations
  • Somatomedins
  • Somatostatin
  • Insulin-Like Growth Factor I
  • Growth Hormone
  • Octreotide