What are the diagnostic tests for pancreatitis (inflammation of the pancreas)?

From the Guidelines

Diagnosing pancreatitis typically involves blood tests, such as serum amylase and lipase, which are digestive enzymes released by the damaged pancreas, with lipase being more specific and remaining elevated longer than amylase, and levels typically rising to three times the normal limit in acute pancreatitis, as stated in the 2019 guidelines 1. The diagnosis of acute pancreatitis should be established within 48 hours of admission, based on compatible clinical features and elevations in amylase or lipase levels, with elevations greater than 3 times the upper limit of normal being most consistent with acute pancreatitis 1. Some key points to consider when diagnosing pancreatitis include:

• Serum lipase is considered a more reliable diagnostic marker of acute pancreatitis than serum amylase, with higher sensitivity and a larger diagnostic window 1.
• In the absence of gallstones or significant history of alcohol use, serum triglyceride should be measured and considered to be the etiology if the value is > 11.3 mmol/l (> 1000 mg/dl) 1.
• Imaging tests, such as abdominal ultrasound, CT scan, MRI, and endoscopic ultrasound, can help determine the presence and severity of pancreatitis, as well as its underlying cause 1.
• Other laboratory findings, such as C-reactive protein, hematocrit, and procalcitonin, can be used to characterize an episode of severe acute pancreatitis and predict the risk of complications 1. The most recent and highest quality study, the 2019 WSES guidelines for the management of severe acute pancreatitis 1, provides the most up-to-date recommendations for diagnosing pancreatitis. Some of the key laboratory tests used to diagnose pancreatitis include:
• Serum amylase and lipase, which are digestive enzymes released by the damaged pancreas
• Complete blood count, metabolic panel, and triglyceride levels
• C-reactive protein, hematocrit, and procalcitonin, which can be used to characterize an episode of severe acute pancreatitis and predict the risk of complications
• Imaging tests, such as abdominal ultrasound, CT scan, MRI, and endoscopic ultrasound, which can help determine the presence and severity of pancreatitis, as well as its underlying cause.

From the Research

Tests for Pancreatitis

• The diagnosis of acute pancreatitis requires the presence of at least two of the three diagnostic criteria - characteristic abdominal pain, elevated serum amylase or lipase, and radiological evidence of pancreatitis 2.
• Serum concentrations of amylase and lipase rise within hours of the pancreatic injury, with a threshold concentration 2-4 times the upper limit of normal recommended for diagnosis 2.
• Serum lipase is now the preferred test due to its improved sensitivity, particularly in alcohol-induced pancreatitis, and its prolonged elevation creates a wider diagnostic window than amylase 2, 3.

Comparison of Serum Amylase and Lipase

• Serum lipase displayed a sensitivity of 91% for acute pancreatitis, against 62% for amylase, with specificity of 92% for lipase and 93% for amylase 3.
• Dual testing with lipase and amylase had a sensitivity of 93% 3.
• Serum amylase and lipase concentrations are not able to establish either the etiology or predict the severity of acute pancreatitis as assessed by imaging techniques 4.

Other Biomarkers

• New biomarkers including trypsinogen and elastase have no significant advantage over amylase or lipase 2.
• Urinary trypsinogen-2 appears to have similar sensitivities and specificities to serum amylase and serum lipase for the diagnosis of acute pancreatitis 5.
• Other biomarkers such as pancreatic elastase, serum trypsin, and phospholipase A2 have been studied, but their practical implications in clinical practice and healthcare are still being researched 6.

Clinical Implications

• About a quarter of people with acute pancreatitis fail to be diagnosed as having acute pancreatitis with the evaluated tests, and about 1 in 10 patients without acute pancreatitis may be wrongly diagnosed as having acute pancreatitis with these tests 5.
• There is a need to increase stress on radiological evidence as well as increase cut-off levels of enzyme elevation for a more accurate diagnosis of acute pancreatitis 6.