The Diagnostic Utility of Insulin-like Growth Factor Binding Protein-3(IGFBP-3) in Growth Hormone Deficiency and Comparison with Insulin-like Growth Factor-I(IGF-I)

Kim, Ki Joong; Shin, Jeh Hoon

Abstract

PURPOSE: For the diagnosis of growth hormone(GH) deficiency in short stature, peak growth hormone levels after pharmacologic stimulation are usually used. In this study, we measured serum IGFBP-3, which is a major binding protein in serum and is considered to be GH-IGF-I axis dependent, levels by radioimmuno assay(RIA) in sera from normal short stature(NSS) children, and patients with GH deficiency children to clarify the utility of IGFBP-3 level as a diagnostic marker for GH deficiency, and compare with IGF-I.
METHODS
At the department of Pediatrics, Hanyang university hospital from November, 1992 to July, 1995, we selected 31 GH deficiency-suspected children on the base of their growth data and bone age. After GH stimulation with clonidine (100-150microg/m2) and L-dopa(200-250mg/m2), we measured their peak GH levels by the immunoradiometric assay(IRMA) kit(Immunodiagnostic system, UK), IGF-I level by Nichols RIA kit after separated from other plasma constituents with YMC-pack Diol 120 column using high-performance liquid chromatography, and IGFBP-3 level by radioimmuno assay(RIA) kit(Diagnostic system labortories, USA).
RESULTS
1)The mean IGF-I and IGFBP-3 level of eight normal short stature(NSS) in Tanner stage I is 124.3+/-7.3ng/mL, 2,400+/-,500ng/mL respectively. 2)The mean IGF-I and IGFBP-3 level of five partial GH deficient(PGHD) children in Tanner stage I is 163.4+/-8.8ng/mL, 1,800+/-,100ng/mL respectively. 3)The mean IGF-I and IGFBP-3 level of six complete GH deficient(CGHD) children in Tanner stage I is 24.5+/-0.0, 700+/-00ng/mL respectively. There is no significant difference of mean IGF-I and IGFBP-3 levels between NSS and PGHD in Tanner stage I, but the mean IGF-I and IGFBP-3 level is significant difference between NSS and CGHD in Tanner stage I(P<0.05). 4)The sensitivity of IGF-I and IGFBP-3 less than 9 years old for CGHD are 100%. The sensitivity of IGF-I and IGFBP-3 for all age in CGHD is 78, 89% respectively. The sensitivity of IGF-I and IGFBP-3 for GH deficiency in less than 9 years is 60, 80% respectively, and in all age is 55, 65% respectively. The specificity of IGF-I and IGFBP-3 for NSS is 55, 64% respectively.
CONCLUSION
Both IGF-I and IGFBP-3 can be useful for screening GH deficiency in Tanner stage I. These two factors are changed according to sexual maturation and nutritional status, but IGFBP-3 has little exogenous effects than IGF-I. Therefore IGFBP-3 may be more sensitive test for diagnosing GH deficiency.