The Renal Clearance of Amylase in Renal Insufficiency, Acute Pancreatitis, and Macroamylasemia

Abstract

The renal handling of amylase was studied in patients with renal insufficiency, acute pancreatitis, and macroamylasemia by measuring the rate of amylase clearance (CAm) relative to the rate of creatinine clearance (CCr). In renal insufficiency CAm was decreased in proportion to CCr. In acute pancreatitis, the kidney cleared amylase at a markedly increased rate. The ratio of the amylase clearance rate to the creatinine clearance rate averaged three times normal early in the course of acute pancreatitis, and this elevation could persist after the serum amylase had returned to normal. This increased clearance of amylase makes the urinary amylase a more sensitive indicator of pancreatitis than is the serum measurement. In contrast to pancreatitis, the high serum amylase levels found in patients with macroamylasemia are associated with an extremely low CAm/CCr ratio. These studies suggest that the diagnostic value of amylase measurements may be enhanced if amylase excretion is related to creatinine excretion.