Amylase isoenzyme clearances in normal subjects and in patients with acute pancreatitis.

Renal clearances of amylase isoenzymes, expressed as percentages of creatinine clearances, were determined in 20 normal subjects and in 8 patients with acute pancreatitis. The isoenzyme assay employed thin layer isoelectric focusing, starch iodine staining, and densitometry. Normal clearance of pancreatic-like amylase (mean +/- SE: 3.00 +/- 0.40%) was greater than the clearance of salivary-like amylase (0.51 +/- 0.06%) in ea ch individual (P less than 0.001). However, the amount of pancreatic amylase in the serum was not the major determinant of amylase clearance. Normal clearance of pancreatic-like amylase was significantly (P less than 0.001) less than the clearance of total serum amylase in acute pancreatitis (6.49 +/- 1.07%). In pancreatitis the clearance of pancreatic-like amylase (7.29 +/- 1.19%) and the clearance of salivary-like amylase (4.55 +/- 1.02%) were both elevated compared to normal (P less than 0.001). These findings indicate that the increased clearance of amylase in pancreatitis results from a change in renal function rather than a change in serum amylase. Renal changes not reflected by increased serum creatinine or more than mild proteinuria may be manifestations of the systemic toxicity of acute pancreatitis.