What is the gold standard test to diagnose pancreatitis?

From the Guidelines

The gold standard test to diagnose pancreatitis is serum lipase measurement. When a patient presents with symptoms suggestive of pancreatitis, such as severe abdominal pain, nausea, and vomiting, a serum lipase level greater than three times the upper limit of normal is considered diagnostic 1. Lipase is preferred over amylase because it remains elevated longer (up to 14 days) and has better sensitivity and specificity, with a sensitivity of 79% and specificity of 89% 1. This enzyme is released by the pancreas during inflammation and injury to pancreatic cells.

Some key points to consider when diagnosing pancreatitis include:

• Serum lipase levels usually rise within 4 to 8 hours, peak at 24 hours, and decrease to normal or near normal levels over the next 8 to 14 days 1
• Amylase levels usually rise within 6 to 24 hours, peak at 48 hours, and decrease to normal or near normal levels over the next 3 to 7 days 1
• Other diagnostic tests that support the diagnosis include abdominal imaging such as CT scan with contrast or MRI/MRCP, which can show pancreatic inflammation, edema, or necrosis 1
• Ultrasound is often performed first to rule out gallstones as a cause
• The diagnosis of pancreatitis typically requires at least two of three criteria: characteristic abdominal pain, elevated pancreatic enzymes (primarily lipase), and imaging findings consistent with pancreatic inflammation 1

Early diagnosis is crucial as severe pancreatitis can lead to significant morbidity and mortality if not properly managed. According to the 2019 WSES guidelines for the management of severe acute pancreatitis, serum lipase is considered a more reliable diagnostic marker of acute pancreatitis than serum amylase 1.

From the Research

Diagnosis of Pancreatitis

• The diagnosis of pancreatitis is based on a combination of clinical assessment and laboratory testing 2, 3, 4.
• There is no single biochemical test that can be considered the "gold standard" for the diagnosis and assessment of severity of acute pancreatitis 2.
• Serum amylase and lipase remain important tests in the diagnosis of acute pancreatitis, with amylase having high sensitivity but low specificity, and lipase having increased sensitivity in acute alcoholic pancreatitis and remaining elevated longer than amylase 2, 3.

Laboratory Tests

• Serum amylase is the cornerstone laboratory test used in establishing the diagnosis of acute pancreatitis, but it has limitations in sensitivity and specificity 4.
• Serum lipase level may be especially useful in patients with alcohol-induced acute pancreatitis 4.
• Other enzymes such as pancreatic isoamylase, immunoreactive trypsin, and elastase are more cumbersome and expensive, and have no clear role in the diagnosis of acute pancreatitis 2, 3.
• A new urinary test strip that uses trypsinogen-2 may have a role in establishing the diagnosis of acute pancreatitis 4.

Imaging Tests

• Computed tomography (CT) and magnetic resonance imaging (MRI) can be used to diagnose advanced chronic pancreatitis, with MRI probably superior in indicating the suitability of fluid collections for percutaneous drainage 5.
• CT is useful for estimating the presence and extent of pancreatic necrosis, and enables prompt recognition of patients at high risk for systemic and local complications 5, 3.
• Ultrasonography remains in the evaluation of the biliary tract in acute pancreatitis 3.