A patient with acute pancreatitis has serum amylase 800 U/L (normal <100 U/L). Which isoform of amylase is elevated, and which organ typically contributes MORE to total serum amylase in healthy individuals?

• A S-type isoamylase elevated; pancreas contributes more in health
• B P-type isoamylase elevated; pancreas contributes more in health
• C Both P- and S-type equally elevated; liver contributes more in health
• D P-type isoamylase elevated; salivary gland contributes more in health ✓

Explanation

In acute pancreatitis the pancreatic (P-type) isoamylase is selectively elevated. Importantly, in healthy individuals the salivary gland (S-type) isoamylase actually contributes approximately 60% of total serum amylase, with the pancreas contributing ~40%. Therefore, macro-amylasemia or salivary gland pathology can also raise total amylase without pancreatitis; isoamylase fractionation helps differentiate. Lipase is more specific for pancreatitis.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.