PLASMA IGFBP-3 AND ITS RELATIONSHIP WITH QUANTITATIVE GROWTH-HORMONE SECRETION IN SHORT CHILDREN

OBJECTIVE We assessed the relationship between serum IGFBP-3 levels wi th IGF-I and quantitative GH secretory status in poorly growing childr en. DESIGN We studied the relationship between 24-hour integrated conc entration of GH, peak GH to paired sequential stimulation tests, IGF-I and the IGFBP-3 serum levels. PATIENTS One hundred and two children ( 82 males, 20 females, age 11.7+/-2.7 years) with short stature (height -2.6+/-0.7 SDS) were studied. MEASUREMENTS Quantitative GH secretory status was assessed by the 24-hour integrated GH and by response to ar ginine and insulin stimulation. GH, IGFBP-3 and IGF-I were measured by radioimmunoassay. To adjust for age and gender, IGFBP-3 levels were c onverted to SD score. RESULTS IGFBP-3 SDS was strongly correlated with IGF-I SDS (r = 0.64, P < 0.0001), and weakly with peak GH (r = 0.28, P < 0.0004), but not with the integrated GH concentration (r = 0.07, P < 0.46). IGFBP-3 SDS increased with pubertal maturation (P < 0.0001). There was no difference in mean IGFBP-3 SDS in subgroupings of the pa tients based on the results of their quantitative GH tests. CONCLUSION in short children, IGFBP-3 levels increase with puberty, are strongly correlated with IGF-I levels, weakly correlated with peak response to GH stimulation tests, but not correlated with integrated GH. Conseque ntly, diagnostic classifications of patients based on quantitative mea surements of GH secretion and IGFBP-3 differ.