Evidence of insulin-like growth factor binding protein-3 proteolysis during growth hormone stimulation testing

J Pediatr Endocrinol Metab. 2011;24(3-4):163-7. doi: 10.1515/jpem.2011.088.

Abstract

Objectives: The ternary complex is composed of insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 and acid labile subunit (ALS). Growth hormone (GH) promotes IGFBP-3 proteolysis to release free IGF-I, ALS, and IGFBP-3 fragments. Our aim was to determine whether elevated GH levels during GH stimulation testing would trigger IGFBP-3 proteolysis.

Design: This prospective study of 10 short prepubertal children (height standard deviation score -2.37 +/- 0.31) used arginine and GH releasing hormone stimulation to study dynamic changes in the ternary complex moieties. IGFBP-3 was measured in two assays: a radioimmunoassay (RIA) that detects both cleaved and intact IGFBP-3; and an immunochemiluminescence assay (ICMA) that detects only intact IGFBP-3.

Results: IGFBP-3 measured by RIA increased by 19% (p < 0.05), while IGFBP-3 measured by ICMA did not significantly increase (6.1%).

Conclusion: The significant increase in IGFBP-3 measured by RIA, but not ICMA, provides evidence of IGFBP-3 proteolysis during acute GH stimulation.

Trial registration: ClinicalTrials.gov NCT00235599.

Publication types

  • Clinical Trial
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arginine / blood
  • Child
  • Dwarfism / drug therapy*
  • Dwarfism / metabolism
  • Female
  • Growth Hormone-Releasing Hormone / therapeutic use*
  • Human Growth Hormone / metabolism*
  • Humans
  • Insulin-Like Growth Factor Binding Protein 3 / blood*
  • Male
  • Prospective Studies
  • Puberty

Substances

  • Insulin-Like Growth Factor Binding Protein 3
  • Human Growth Hormone
  • Growth Hormone-Releasing Hormone
  • Arginine

Associated data

  • ClinicalTrials.gov/NCT00235599