Serum IGF-1 in treated acromegaly - how normal is "normal"?

Pituitary. 2005;8(2):135-8. doi: 10.1007/s11102-005-4241-z.


We describe four acromegalic patients with persisting typical symptoms - excessive sweating, lack of suppleness of hands, joint pains - despite the achievement of normal serum IGF-1 levels after pituitary surgery. In three patients there was a clear improvement in symptoms when lower IGF-1 levels within the normal range were achieved with pegvisomant treatment. In the fourth patient IGF-1 levels have fluctuated within the normal range with persistence of abnormal sweating, particularly at night. Two of three patients who had an oral glucose tolerance test when serum IGF-1 was in the normal range failed to suppress GH levels to less than 1 ng/ml. We conclude that, in the treated acromegalic patient, IGF-1 levels within the normal range need to be looked at critically to determine what is truly normal for that individual. Relief of symptoms seems a reasonable yardstick, in addition to population norms, by which to judge whether the prevailing IGF-1 level is appropriate; in some cases the aim should be an IGF-1 level in the lower half of the normal range, or perhaps even the lowest quartile.

Publication types

  • Case Reports

MeSH terms

  • Acromegaly / blood*
  • Acromegaly / therapy
  • Adult
  • Female
  • Human Growth Hormone / analogs & derivatives
  • Human Growth Hormone / therapeutic use
  • Humans
  • Insulin-Like Growth Factor I / analysis*
  • Male
  • Middle Aged
  • Reference Values


  • Human Growth Hormone
  • Insulin-Like Growth Factor I
  • pegvisomant