Interpretation of serum amylase levels in the critically ill patient.

To understand better the incidence and meaning of hyperamylasemia in the intensive care setting, cellulose acetate membrane electrophoresis was used to measure the isoenzymes of serum amylase in 192 patients with a variety of critical illnesses. Seventy of these patients had elevated serum amylase levels, but none had clinical or biochemical evidence of acute pancreatitis or renal failure. Of the 70 patients who had hyperamylasemia, in only 18 (26%) was it due solely to an elevation of the pancreatic isoamylase fraction. The remaining 52 patients were hyperamylasemic due to elevations in the nonpancreatic isoamylase fraction or elevations in both pancreatic and nonpancreatic isoamylase fractions. These data indicate that hyperamylasemia in the absence of clinical pancreatic disease is common in the ICU and is frequently caused by nonpancreatic production of serum amylase. Caution is, therefore, advised in interpreting elevated serum amylase levels in critically ill patients.