Measurement of growth hormone, insulin-like growth factor I and their binding proteins: the clinical aspects

Background: Growth hormone (GH) secreted from the pituitary stimulates the production of insulin-like growth factor I (IGF-I) from the liver and extra hepatic tissues, which in turn regulates tissue proliferation and different iation in an endocrine or autocrine/paracrine manner. Both GH and IGF-I cir culates as complexes with specific binding proteins. The GH binding protein (GHBP) corresponds to the extracellular. ligand-binding domain of the GH r eceptors in tissues and its serum concentration may reflect the status of t he tissue receptors. Most serum IGF-I associates with IGF binding protein 3 (IGFBP-3) and another protein, the acid labile subunit (ALS). Like IGF-I, serum concentrations of IGFBP-3 and ALS are tightly regulated by GH. GH sec retion (both spontaneous and stimulated), IGF-I, IGFBP-3, and ALS have been assessed as potential biochemical markers for diagnosis of GH-related diso rders. Conclusions: In acromegaly, IGF-I is the most reliable marker. The p eak GH response to insulin tolerance test is the diagnostic test of choice, GH deficiency. GHBP has no diagnostic value in acromegaly or GH deficiency . However, it may be a potential biochemical marker for GH insensitivity sy ndrome as serum GHBP concentrations are undetectable or reduced in > 75% of these patients. Other biochemical tests may also prove to be useful in the se disorders, but require further validation. (C) 2001 Elsevier Science B.V . All rights reserved.