From the Guidelines
The diagnostic test of choice for pancreatitis is serum lipase measurement, as it is more sensitive and specific than amylase for diagnosing pancreatitis, with levels typically rising within 4-8 hours of symptom onset and remaining elevated for 8-14 days. Lipase is considered a more reliable diagnostic marker of acute pancreatitis than serum amylase due to its higher sensitivity and larger diagnostic window 1. A lipase level greater than three times the upper limit of normal, combined with characteristic clinical symptoms (severe epigastric pain, often radiating to the back, nausea, and vomiting), strongly supports the diagnosis of acute pancreatitis. Some key points to consider in the diagnosis of pancreatitis include:
- Serum lipase is preferred over total and p-amylase for the diagnosis of acute pancreatitis due to its higher sensitivity and specificity 1
- Amylase can also be measured but is less specific as it may be elevated in other conditions, such as renal disease, appendicitis, acute cholecystitis, chronic pancreatitis, bowel obstruction, etc. 1
- After initial laboratory testing, contrast-enhanced CT scan is recommended for patients with uncertain diagnosis, severe symptoms, or lack of improvement after 48-72 hours to assess for complications such as necrosis or pseudocysts 1
- Ultrasound is useful primarily to evaluate for gallstones as a potential cause of pancreatitis but has limited value in directly visualizing the pancreas 1
- MRCP (Magnetic Resonance Cholangiopancreatography) may be used when biliary etiology is suspected but is not the first-line diagnostic test 1
From the Research
Diagnostic Tests for Pancreatitis
- The diagnosis of acute pancreatitis can be established using a combination of clinical assessment and laboratory testing 2.
- Serum amylase is the most widely used test to diagnose acute pancreatitis, but its popularity does not appear to be justified due to its poor sensitivity and specificity 3.
- Serum lipase is considered a better test to diagnose acute pancreatitis, with studies showing it to be more sensitive and specific than amylase 3, 4, 5.
- The sensitivity of lipase for acute pancreatitis is around 91%, compared to 62% for amylase 4.
- Specificity of lipase is around 92%, compared to 93% for amylase 4.
Imaging Techniques
- Computerized tomography (CT) scanning is the best method to delineate the pancreas, but ultrasound is more cost-effective in clinical practice 3.
- Contrast-enhanced computed tomography (CECT) is useful for estimating the presence and extent of pancreatic necrosis, and can help identify patients at high risk for systemic and local complications 5.
Other Biomarkers
- Other enzymes such as P-isoamylase, immunoreactive trypsin, chymotrypsin, or elastase are more cumbersome, expensive, and not better than lipase, and should be reserved for cases of doubtful diagnoses 5.
- Newer biomarkers such as pancreatic elastase, serum trypsin, urinary trypsinogen-activated peptide, phospholipase A2, carboxypeptidase B, and circulating cell-free DNA are being validated for the diagnosis of acute pancreatitis 6.
- C-reactive protein is a reasonably reliable indicator of severity and should be used more frequently 3.