A 52-year-old asymptomatic man is found on routine testing to have serum amylase of 350 U/L, unchanged over three annual reviews. He has no abdominal pain. Serum lipase is normal, urine amylase is normal, and amylase electrophoresis shows a broad abnormal band. The most likely explanation is:
- A Chronic pancreatitis with residual acinar damage
- B Renal failure causing reduced amylase clearance
- C Macroamylasaemia, where amylase bound to immunoglobulin escapes glomerular filtration ✓
- D Sialadenitis with recurrent salivary enzyme release
Correct answer: C. Macroamylasaemia, where amylase bound to immunoglobulin escapes glomerular filtration
Explanation
Macroamylasaemia is a benign condition in which amylase complexes with immunoglobulin (usually IgA or IgG), forming a particle too large for glomerular filtration. It persists in serum, is absent from urine, and causes no symptoms. Chronic pancreatitis would elevate lipase and cause pain; renal failure elevates both amylase and lipase through reduced clearance; sialadenitis produces episodic rather than fixed elevation with a normal isoenzyme band.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.