EFFECTS OF IGF-I ON RENAL-FUNCTION IN PATIENTS WITH CHRONIC-RENAL-FAILURE

Insulin-like growth factor I (IGF-I) has been shown to increase glomer ular filtration rate and renal plasma flow in rats and humans with nor mal renal function. However, rats with reduced renal function are resi stant to these effects. To determine whether IGF-I affects glomerular filtration rate and renal plasma flow in humans with reduced renal fun ction, we administered recombinant human IGF-I (rhIGF-I) to patients w ith moderate chronic renal failure. Four patients whose baseline inuli n clearances were 21.9, 23.2, 34.9, and 55.1 ml.min-1.1.73 m-2 were pl aced on a 1 g.kg-1.day-1 protein diet and studied over a 10-day period (0-10). On days 4-7, 100 mug/kg of rhIGF-I was subcutaneously adminis tered twice daily to the patients. The effects of rhIGF-I on levels of circulating IGF-I, inulin clearance, p-aminohippurate (PAH) clearance , kidney volume, plasma glucose, plasma and urine calcium and phosphat e, and urine sodium and protein were determined. Administration of rhI GF-I increased levels of circulating IGF-I, inulin clearances, PAH cle arances, and kidney size in each of the four patients receiving the gr owth factor. IGF-I did not cause weight gain, natriuresis, proteinuria , or hypoglycemia. Plasma calcium and phosphate were not affected by r hIGF-I. However, the percent tubular reabsorption of filtered phosphat e was increased. We conclude that administration of rhIGF-I can enhanc e glomerular filtration rate and renal plasma flow at least in some hu mans with moderately reduced renal function. The enhancement is associ ated with an increase in kidney volume.