Plasma levels of insulin-like binding protein-2 in prepubertal short children and its diagnostic value in the evaluation of growth hormone deficiency

Aim: This study was designed to investigate whether determination of plasma insulin-like growth factor (IGF)binding protein-2 (IGFBP-2) levels could b e of benefit in the evaluation of childhood growth hormone (GH) deficiency (GHD). Method. A retrospective analysis was performed on 91 prepubertal chi ldren referred for investigation of short stature. Maximal GH levels in pla sma after provocative stimuli were between 1.0 and 93.0 mU/I, 6 subjects ex hibiting peak values of <5 mU/I. Initially a GH peak of 20 mU/I was used as a cutoff limit to define GHD and idiopathic short stature (ISS) patients. The results of GH provocative tests were compared to age- and gender-based standard deviation scores (SIDS) of plasma IGFBP-2, IGF-I, IGFBP-3 and the molar ratios of the latter two to IGFBP-2. The respective normative range v alues for these parameters were determined in plasma samples from 353 healt hy children (i.e. 171 girls, 182 boys). Results: Circulating IGFBP-2 levels did not correlate with height SIDS, height velocity SIDS or the peak GH le vels after provocative stimuli. A weak negative relationship was found betw een IGFBP-2 and IGF-I. Plasma levels of IGFBP-2 in GHD patients were higher than those of ISS children, who had normal levels. Although at the optimal cutoff point of -0.71 SDS 91.5% of the GHD patients were identified correc tly, a substantial proportion (71.9%) of the ISS subjects also had IGFBP-2 levels above this limit. The use of various combinations of IGFBP-2, IGF-I, IGFBP-3 and the derived ratios only slightly improved the diagnostic effic iency as compared to the results of the individual tests. Neither IGFBP-2 n or the IGFBP-3/IGFBP-2 and IGF-I/IGFBP-2 ratios were found to be related to the short- (1 year) or long-term (3 years) growth response to GH therapy. Conclusion: It is concluded that none of the tests investigated, either alo ne or in various combinations, are reliable in either predicting the peak G H level after provocative stimuli in prepubertal short children or in predi cting their growth response to GH. Copyright (C) 2001 S. Karger AG, Basel.