What is the difference between amylase and lipase in the context of pancreatic disease?

From the Guidelines

Lipase is the preferred diagnostic test for acute pancreatitis due to its higher specificity and sensitivity compared to amylase. The key differences between amylase and lipase in the context of pancreatic disease are their specificity, sensitivity, and the duration for which they remain elevated.

• Lipase is more specific to pancreatic inflammation and remains elevated for a longer period, typically 7-14 days, making it a more reliable marker for acute pancreatitis 1.
• Amylase, on the other hand, rises quickly but returns to normal within 3-5 days and can be elevated in non-pancreatic conditions, leading to false positives 1.
• The sensitivity and specificity of serum lipase are 79% and 89%, respectively, compared to 72% and 93% for serum amylase, as shown in a Cochrane revision 1.
• In clinical practice, lipase is often the only test needed for diagnosing acute pancreatitis, with levels typically rising to three times the upper limit of normal 1. Some important points to consider when evaluating patients with suspected pancreatic disorders include:
• The magnitude of enzyme elevation does not reliably indicate disease severity, and monitoring these levels is not recommended for tracking recovery 1.
• Other laboratory findings, such as BUN, hematocrit, lactate dehydrogenase, and procalcitonin, can be used to characterize an episode of severe acute pancreatitis and predict infected necrosis 1.
• Resistin, a newly identified peptide hormone, has been shown to be a promising marker for predicting the severity of acute pancreatitis and the development of necrosis 1.

From the Research

Difference between Amylase and Lipase

• Amylase and lipase are two enzymes produced by the pancreas that play crucial roles in digestion [ 2 ].
• Amylase breaks down carbohydrates into simple sugars, while lipase breaks down fats into fatty acids and glycerol [ 2 ].

Diagnostic Accuracy in Acute Pancreatitis

• Serum lipase offers a higher sensitivity than serum amylase in diagnosing acute pancreatitis [ 2 ].
• Lipase also offers a larger diagnostic window than amylase, as it remains elevated for a longer period [ 2 ].
• A study comparing lipase and amylase in the diagnosis of acute pancreatitis found that lipase was elevated in 100% of patients, while amylase was elevated in 95% [ 3 ].
• The receiver-operating characteristics (ROC) curves showed similar curves for both enzymes, with lipase being slightly superior to amylase [ 3 ].

Clinical Utility of Amylase and Lipase

• A comparative study of serum amylase and lipase in acute pancreatitis patients found that all 50 patients had raised serum lipase, while 42 patients had both amylase and lipase raised [ 4 ].
• The study suggested that estimation of serum lipase may be a better choice over serum amylase in the diagnosis of acute pancreatitis, especially in smaller hospitals with limited lab facilities [ 4 ].
• The diagnosis of acute pancreatitis requires two of the following: upper abdominal pain, amylase/lipase ≥ 3 × upper limit of normal, and/or cross-sectional imaging findings [ 5 ].

Specificity and Sensitivity of Amylase and Lipase

• A study found that the simultaneous determination of serum lipase and amylase marginally improved the diagnosis of acute pancreatitis, but the sensitivity of the assay remained low, especially in samples collected 4-5 days after the onset of the disease [ 3 ].
• The combination of both parameters mainly improved the specificity of the assay, but only when twofold elevated amylase was combined with lipase [ 3 ].