Yes, Amylase is a Blood Test
Yes, serum amylase is a blood test, and in this 55-year-old woman presenting with nausea, vomiting, urticaria, and pale dough-like stools after COVID-19, it should be measured along with lipase to assess for pancreatic involvement.
Why Measure Serum Amylase in This Context
The pale dough-like stools suggest possible pancreatic insufficiency or biliary obstruction, making pancreatic assessment critical. While COVID-19 primarily affects the respiratory system, pancreatic involvement has been documented 1.
Key Clinical Considerations:
Serum amylase is measured from blood, typically rising within 6-24 hours of pancreatic injury, peaking at 48 hours, and normalizing over 3-7 days 2. However, lipase is the preferred test as it has higher sensitivity (79% vs 72%) and remains elevated longer (8-14 days vs 3-7 days) 2.
COVID-19 and Pancreatic Enzyme Elevation
Critical finding: Elevated pancreatic enzymes occur in approximately 25.4% of COVID-19 patients when defined as above upper limit of normal, with 6.1% showing levels >3× upper limit of normal 3. However, elevated amylase does not necessarily indicate acute pancreatitis 4, 5.
Important Distinctions:
- Hyperamylasemia in COVID-19 is more commonly associated with disease severity rather than true pancreatitis 5
- Only a small minority develop actual acute pancreatitis (4 out of 1858 patients in one study) 5
- Elevated amylase correlates with ICU admission risk but not necessarily mortality 5
- Pancreatic density changes on CT may occur without corresponding enzyme elevations 6
Recommended Diagnostic Approach
For this patient, order both serum amylase AND lipase 2, 7:
If either enzyme >3× upper limit of normal: Consider acute pancreatitis per Atlanta criteria and obtain abdominal CT 2, 7
If enzymes mildly elevated (<3× ULN): This likely reflects COVID-19 severity rather than pancreatitis 5, 3
Check additional tests:
Critical Pitfall to Avoid
Do not assume elevated amylase equals pancreatitis in COVID-19 patients 4, 5. The pale stools in this case are more suggestive of biliary obstruction or pancreatic exocrine insufficiency requiring different evaluation (abdominal ultrasound, fecal elastase) rather than acute pancreatitis workup.
Prognostic Value:
Patients with elevated pancreatic enzymes (either type) have worse outcomes including increased ICU admission, mechanical ventilation needs, and mortality (34.6% mortality with any elevation, 39.2% with >3× ULN) 3. This makes measurement clinically valuable for risk stratification even when true pancreatitis is absent.