Amylase to creatine clearance ratio in renal diseases.

In order to assess to what extent glomerular or tubular function is involved in the renal handling of amylase and the lysozyme to creatine clearance ratios (CAm/CCr and CLys/CCr) were evaluated in 22 healthy volunteers and in 71 patients with different renal diseases. In normal controls, the mean CAm/CCr was 2.55 +/-1.54 SD, with an upper normal limit of 5.56. A normal ratio was found in patients with glomerulonephritis, with or without a nephrotic syndrome, and in patients with pyelonephritis. A significantly elevated ratio (P less than 0.001) was instead found in patients with uremia and in patients with uremia and in patients with either chronic or acute tubular damage. The CLus/CCr ratio was elevated in all the groups, except in patients with glomerulonephritis and minimal proteinuria. These results show that in humans, as in animals, the amylase filtered load undergoes partial tubular reabsorption. In renal diseases, an increase of the CAm/CCr is caused by either a marked reduction of functioning nephrons or a severe tubular damage, while the glomerular permeability does not seem to be involved. Some other mechanism is probably involved in the elevation of the CAm/CCr during acute pancreatitis.