Characteristics of Insulin-Like Growth Factor I in Serum; Pattern of Insulin-Like Growth Factor Binding Protein(Large Complex) in Short Stature Patients with Complete Growth Hormone Deficiency

ABSTRACT

To elucidate the complex of insulin-like growth factor binding proteins (IGF-BPs) in short stature patients, we carried out a prospective study on three patients who were diagnosed as complete GH deficiency at the department of pediatrics from July 1992 to June 1993. The results were summarized as follows 1) Two circulating IGFs complexed to specific binding protein existed in normal serum. Binding activity was found to be in the 150,000 molecular weight area (the large complex) and 50~60,000 molecular weight area (the small complex). 2) Binding activity for the large complex was seen to be dependent on advancing age, level of large IGF-BP3 complex peacked at the age of 15~16 years. 3) The binding activity for large complex diminished in three GH deficient patients and increased after hGH injection to near or above normal level. 4) Increased growth rate after GH treatment in GH deficient patient was closely related with increasing level of the large IGF-BP3 complex. Therefore we suggest that the large IGF-BP3 complex is regulated by GH. Estimating its serum level is useful for screening of GH deficiency and the monitoring of response to GH therapy.