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.