THE SHORT-TERM INCREASES OF IGF-I AND IGFBP-3 DURING GH TREATMENT PREDICT THE LONG-TERM GROWTH RESPONSE IN SHORT CHILDREN

Abstract

The treatment of short children without GH deficiency (GHD) poses a major question: whether or not short-term changes of GH-dependent parameters could predict the long-term growth response to GH treatment. For this purpose, scrum IGF-I and IGFBP-3 levels were studied in short prepubcrtal children without “classical” GHD as defined by a peak GH level above 20 mU/L in the arginine-insulin-tolerance test (5 girls, 33 boys, age 8.9±1.9 yr) receiving 0.1 IU rhGH per kg body weight daily. Height velocity (HV) was determined during a 1-yr pretreatment period and during the 1st (n=38) and 2nd (n=32) year of treatment. IGF-I and IGFBP-3 were measured by specific RIAs at start of therapy (index 0) and after 1 month (index 1m).Results: HV (mean±SD) increased from 4.97±1.04 cm/yr to 7.60±0.99 and 6.42±1.24 cm/yr during the 1st and 2nd year resp. The 1 month increase of IGF-I levels was from 131±54 μg/l 199±90 μg/l and of IGFBP-3 from 2.84±0.68 mg/l to 3.57±0.90 mg/l. The correlation coefficients and p-values between IGF-parameters (IGF-I0, ΔIGF-I= IGF-I1m - IGF-I0 %IGF-1= IGF-I1m/IGF-I0. IGFBP-3 accordingly) and the increases of HV during the 1st (ΔHV1) and 2nd year (ΔHV2) are given below (rs(p):Conclusions: 1) Low basal IGF-I and IGFBP-3 levels predict a good growth response during the 1st year, but not thereafter. 2) The predictive potential of the short-term increases of IGF-I and IGFBP-3 is belter for the 2nd year than Die 1st year. 3) IGFBP-3 is superior to IGF-I due to its negligible circadian fluctuations during GH therapy.