IGF-I levels rise and GH responses to GHRH decrease during long-term prednisone treatment in man.

Area of Science:

• Endocrinology
• Pharmacology
• Metabolism

Background:

• Glucocorticoid excess is linked to altered growth hormone (GH) secretion.
• Insulin-like growth factor-I (IGF-I) levels in hypercortisolism are variable, with conflicting reports.
• The longitudinal effects of corticotherapy on GH, IGF-I, and related proteins require further investigation.

Purpose of the Study:

• To longitudinally assess time-dependent changes in GH response to GHRH, IGF-I, IGF-Binding Protein-3 (IGFBP-3), and albumin during prednisone treatment.
• To compare these parameters between patients undergoing corticotherapy and healthy controls.

Main Methods:

• Six patients received GHRH tests before, after one week, and after one month of oral prednisone (20-60 mg/d).
• IGF-I, IGFBP-3, and albumin levels were measured at each time point.
• Ten normal controls were evaluated for comparison.

Main Results:

• Prednisone administration significantly decreased peak GH response to GHRH after one week and one month.
• Circulating IGF-I levels significantly increased after one week and one month of prednisone.
• Albumin levels rose significantly during prednisone treatment, while IGFBP-3 showed no significant change.

Conclusions:

• Corticotherapy with prednisone markedly reduces GH responsiveness to GHRH.
• Prednisone administration is associated with increased circulating IGF-I and albumin levels.
• The exact physiological mechanisms, potentially involving increased hepatic synthesis, require further elucidation.