Clearance ratios of amylase and isoamylase to creatinine in renal disease.

Amylase to creatinine clearance ratios were measured in 66 patients with a variety of moderate and severe renal diseases including 10 patients with renal transplants, and in 13 healthy controls. Only in patients with severe renal insufficiency (serum creatinine level above 660 micronmoles/1) were the amylase to creatinine ratios significantly raised. The ratios correlated neither with the type of renal disease, i.e. glomerular or tubulointerstitial, nor with the degree of proteinuria. Patients with renal transplants did not differ from other patients. Clearance ratios of pancreatic and salivary isoamylase to creatinine changed in parallel to that of total amylase. The results suggest that in severe renal failure the loss of nephrons results in decreased fractional reabsorption of amylase in the tubules.