A 62-year-old woman with chronic kidney disease on conservative management (creatinine 4.5 mg/dL) is found to have serum amylase of 310 U/L (normal <110). She has no abdominal pain, and lipase is 45 U/L. The MOST appropriate interpretation is:

• A Silent acute pancreatitis requiring imaging confirmation
• B Macroamylasemia due to circulating immune complexes
• C Salivary gland disease such as sialadenitis
• D Reduced renal clearance of amylase causing benign elevation ✓

Explanation

Amylase is a small enzyme cleared predominantly by the kidneys, so glomerular filtration failure produces moderate asymptomatic elevations, typically up to two to three times normal. Lipase is partly taken up and degraded by the kidney rather than solely filtered, so it is characteristically spared, which fits this patient. The normal lipase and absent symptoms argue against pancreatitis, and macroamylasemia shows a persistently high amylase with LOW urinary amylase because the macrocomplex cannot be filtered.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.