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

OBJECTIVE We assessed the relationship between serum IGFBP-3 levels with IGF-I DESIGN We studied the relationship between 24-hour integrated concentration 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 arginine and insulin stimulation. GH, IGFBP-3 and IGF-I were measured by radioimmunoassay. To adjust for age and gender, IGFBP-3 levels were converted 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 patients 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. Consequently, diagnostic classifications of patients based on quantitative measurements of GH secretion and IGFBP-3 differ.