PERITONEAL LOSS OF INSULIN-LIKE GROWTH-FACTOR-I AND BINDING-PROTEINS IN END-STAGE RENAL-DISEASE

The kinetics of peritoneal transport of insulinlike growth factor (IGF ) system-related proteins during dialysis is not well characterized. W e studied temporal changes in dialysate and serum concentrations of IC E-I and IGF-II as well as IGF binding protein (BP)-1, -2, and -3 in te n children with end-stage renal disease (ESRD) undergoing continuous c ycling peritoneal dialysis (CCPD) during a 4-h peritoneal equilibratio n test (PET). Dialysate concentrations of IGF-I, IGF-II, and all three IGFBPs demonstrated a time-dependent increase during PET. Despite the ir transport, the serum concentrations of these proteins did not chang e significantly during the PET. Dialysate/serum ratios for IGF-I, IGF- II, and IGFBP-1, -2, and -3 were significantly increased at 2 h and in creased further at 4 h, at which time values averaged 1.3+/-0.2%, 3.1/-0.5%, 6.2+/-1.0%, 2.4+/-0.2%, and 1.3+/-0.2% of serum levels, respec tively. The transperitoneal clearance (mu l/min per 1.73 m(2)) of the three IGFBPs was inversely related to both their molecular weight and plasma concentration. However, peritoneal clearance of IGF-I and -II w as similar to that of the larger and more-abundant IGFBP-3. Mass trans fer rates (mu g/h per 1.73 m2) for the IGFs and their binding proteins were directly proportional to their prevailing plasma concentration. Based on estimates of mass transfer, only a small molar excess of IGFB Ps was removed from the circulation relative to the combined molar con centration of IGF-I and ICE-II. Hence, it seems unlikely that any bene ficial effect of CCPD on growth in children with ESRD is mediated via a preferential loss of IGFBPs into the dialysate fluid.