A 40-year-old asymptomatic man undergoing routine screening has serum amylase persistently 320 U/L (normal <110 U/L) on three occasions over two months. He has no abdominal pain, lipase is normal, and urinary amylase excretion is normal. Serum protein electrophoresis is unremarkable. The MOST likely explanation is:
- A Chronic pancreatitis with early pancreatic insufficiency
- B Macroamylasemia ✓
- C Parotitis with salivary-type hyperamylasemia
- D Renal failure reducing amylase clearance
Correct answer: B. Macroamylasemia
Explanation
Macroamylasemia is a benign condition in which amylase complexes with immunoglobulin (usually IgG or IgA) forming a macromolecule too large for glomerular filtration. Serum amylase is persistently elevated but urinary amylase is normal or low, and there are no symptoms. Renal failure would reduce clearance but usually elevates both serum and reduces urine amylase with other uremic findings, and the absence of pain excludes pancreatitis.
Reference: Harper's Illustrated Biochemistry, 31st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.