What does it mean when lipase is low and amylase is high?

Elevated Amylase with Low Lipase: Diagnostic Implications

When amylase is elevated but lipase is low, this pattern suggests non-pancreatic conditions rather than acute pancreatitis, as lipase is more specific for pancreatic injury and would typically be elevated in true pancreatic inflammation. 1

Common Causes of Isolated Amylase Elevation

• Amylase can be elevated in non-pancreatic conditions including head injuries, hepatic injuries, bowel injuries, and after hypo-perfusion of the pancreas 2
• Salivary gland disorders (mumps, salivary gland obstruction) can cause elevated amylase without affecting lipase 1
• Renal insufficiency may cause amylase retention while lipase remains normal 3
• Macroamylasemia (a condition where amylase binds to proteins and cannot be filtered by kidneys) 1
• Certain malignancies can produce amylase without affecting lipase levels 3

Diagnostic Significance

• Lipase is considered more reliable and specific for pancreatic injury than amylase 2
• In true acute pancreatitis, both enzymes are typically elevated, with lipase showing higher sensitivity (79% vs 72% for amylase) 2
• When lipase is normal but amylase is elevated, acute pancreatitis is unlikely as the diagnosis 3
• The American Gastroenterological Association recommends determining if amylase elevation is significant (>3 times upper limit of normal) for diagnosing acute pancreatitis 1

Clinical Approach to Discordant Enzyme Levels

• When amylase is elevated but lipase is normal, consider non-pancreatic sources of amylase 3
• Simultaneous determination of both enzymes is recommended for accurate evaluation of patients with abdominal pain 3
• The diagnostic window differs between these enzymes: amylase rises within 6-24 hours and normalizes in 3-7 days, while lipase rises within 4-8 hours and remains elevated for 8-14 days 2
• If clinical suspicion for pancreatic pathology remains despite normal lipase, imaging studies such as contrast-enhanced CT should be considered 2, 1

Important Considerations

• The degree of enzyme elevation does not correlate with severity of disease 1
• Lipase levels drawn on admission can exclude pancreatic injury with a negative predictive value of 99.8% 2
• When amylase and lipase are used together with ultrasonography, sensitivity of 88% and 96% negative predictive value can be achieved 2
• Persistently elevated serum amylase after 10 days from initial injury should be monitored closely due to increased risk of pseudocyst formation 2

Recommended Diagnostic Algorithm

1. Measure both amylase and lipase in patients with suspected pancreatic pathology 3
2. If lipase is normal but amylase is elevated, consider non-pancreatic causes 3
3. Perform abdominal ultrasound to detect gallstones, free peritoneal fluid, or biliary duct dilation 1
4. Consider contrast-enhanced CT scan if clinical suspicion remains high despite discordant enzyme levels 2, 1
5. Investigate other potential causes including renal disease, salivary gland disorders, or malignancies 3
6. Monitor enzyme levels serially, as decreasing levels correlate with successful management 1

This pattern of elevated amylase with normal lipase should prompt consideration of alternative diagnoses rather than acute pancreatitis, as lipase is the more specific marker for pancreatic inflammation 2, 3.