URINARY-EXCRETION OF EPIDERMAL GROWTH-FACTOR IN LIVING HUMAN KIDNEY DONORS AND THEIR RECIPIENTS

Epidermal growth factor (EGF) is a growth-promoting peptide that is sy nthesized in the distal tubules of the kidney and excreted in urine. E GF has been suggested to play a role in the repair after renal tissue damage, as well as in compensatory growth of the remaining kidney afte r uninephrectomy. The present study examined the urinary EGF excretion after uninephrectomy and transplantation among relatives. The urinary EGF excretion rate and the glomerular filtration rate (GFR) were foll owed for 26-54 days in 16 healthy kidney donors and nine recipients. A fter uninephrectomy the median urinary EGF excretion rate in the donor s was not 50% of the pre-operative value, but around 65% (95% confiden ce limits of the median on the fifth post-operative day: 59-72%). This suggests that there is a compensatory increase in the EGF excretion r ate from the remaining kidney of around 30% after uninephrectomy. A si milar compensatory increase was demonstrated for GFR, indicating that the compensatory changes in EGF excretion rate and GFR might be correl ated. In the transplanted kidneys, GFR was consistently around 15% low er and EGF excretion rate around 40% lower than in the corresponding k idneys remaining in the donors. This might reflect ischaemic and drug- induced damage of the transplanted kidneys. The present study demonstr ated a compensatory increase of around 30% in urinary EGF excretion fr om the remaining kidney after uninephrectomy in healthy humans. Whethe r EGF plays a role in the adaptive processes in the remaining kidney o r whether changes in EGF excretion are merely of a secondary nature is still uncertain.