Diagnose pancreatitis, more specific for pancreatitis than is serum amylase; diagnose peritonitis, strangulated or infarcted bowel, pancreatic cyst.
Serum lipase is usually normal in patients with elevated serum amylase, without pancreatitis, who have peptic ulcer, salivary adenitis, inflammatory bowel disease, intestinal obstruction, and macroamylasemia. Coexistence of increased serum amylase with normal lipase may be a helpful clue to the presence of macroamylasemia.1 Lipase is elevated with amylase in acute pancreatitis, but the elevation of lipase is more prolonged.
In work-up of pancreatitis, in addition to serum lipase and amylase, the 2-hour urine amylase is of value. Electrolytes, serum calcium, glucose, and acetone are also often needed. Immunoreactive trypsin is technically more difficult than lipase and probably no better.2 The serum lipase:amylase ratio may help distinguish alcoholic from nonalcoholic pancreatitis. Ratios >2 (expressed as multiples of the upper limits of normal) suggest an alcoholic etiology.3 Lipase isoform or isoenzymes have been studied.4