Serum amylase is elevated 5-fold above normal in a patient with abdominal pain. Which additional finding would most specifically confirm acute pancreatitis rather than other causes of hyperamylasemia?
- A Urinary amylase-to-creatinine clearance ratio >5%
- B Salivary isoamylase fractionation showing pancreatic isoform >60%
- C Serum lipase elevation >3-fold upper limit of normal ✓
- D Serum amylase >1000 IU/L
Explanation
Serum lipase elevation greater than 3 times the upper limit of normal is the most specific indicator of acute pancreatitis, as lipase is produced almost exclusively by pancreatic acinar cells. Amylase can rise in salivary gland disease, macroamylasemia, intestinal ischemia and renal failure, making it less specific. The amylase-to-creatinine clearance ratio was historically used but has poor specificity. Absolute amylase values do not determine etiology. Isoamylase fractionation identifying pancreatic P-isoform increases specificity of amylase testing but lipase remains superior.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.