The effect of dialyzer membrane and etiology of kidney disease on the preservation of residual renal function in chronic hemodialysis patients.

It is commonly believed that renal function rapidly decreases in the vast majority of chronic hemodialysis patients. Three hundred thirty-four patients starting chronic hemodialysis between 1/1/88 and 12/31/92 at six hemodialysis units were prospectively studied. Renal function was determined every 3 months by 68 hr urine collection expressed as weekly fraction urea clearance (L/L total body water/wk). glomerular filtration rate was calculated from the mean of the urea and creatinine clearance. After 3 years, glomerular filtration rate exceeded 4 ml/min in 14% of patients. For a thrice weekly dialysis schedule, it was assumed that a weekly fractional urea clearance of 3 L/L/wk is equal to a dialysis KT/V of 1 and patients need a minimum KT/V of 1.2 per treatment. After 3 years of chronic hemodialysis therapy, residual renal function was found to provide 15% of the dialysis requirement in 19% of patients and 30% of the dialysis requirements in 9% of patients. The occasional patient maintains sufficient residual renal function to provide over 40% of the dialysis requirement for over 4 years. In a retrospective analysis, patients treated only with Cupraphan membrane had a more rapid loss of renal function compared to those never treated with Cupraphan (Besnberg Corp., Germany). The majority of patients with polycystic kidney disease maintained a glomerular filtration rate greater than 2 ml/min for 4 years or longer.