[Renal excretion of amino acids in patients on a regular dialysis program]

In 10 patients with chronic renal failure and a polyfructosan S clearance (CPFS): 1.91-12.70 ml/min (mean 5.68 ml/min) with a preserved residual diuresis (more than 1000 ml/24 hours) renal excretion of 22 amino acids by residual nephrons was investigated before and 12 hours after haemodialysis. It was revealed that 12 hours after haemodialysis a significant drop of the filtered amount of all investigated amino acids occurred. Renal clearance of Ser, Pro, Glu, Gly, Ala, Tyr, Met, Leu and Cit after haemodialysis declined significantly (p < 0.05-0.001). Haemodialysis was not associated with significant changes of fractionated excretions (FE) of amino acids with the exception of Gly (p < 0.01) and Trp (p < 0.05) where an increase of FE was recorded. Hitherto assembled results are consistent with the idea that a reduction of the tubular resorption of amino acids in the residual nephrons in subjects with chronic renal failure cannot be explained by a change of their filtered amount (as "overflow" aminoaciduria) nor as the consequence of retention of some dialyzable substances which could inhibit tubular transport of amino acids. The reduced tubular transport of some of the investigated amino acids (Cys, Lys, Cit, Met, Asn+Gln, Orn, Ile) was significantly related with the drop of tubular sodium transport.