- Blood Investigations - Full blood count, Renal function tests, Liver Function, serum calcium, serum amylase and lipase, Arterial blood gas
- Imaging - Chest Xray (for exclusion of perforated viscus), Abdominal Xrays (for detection of "sentinel loop" dilated duodenum sign, and gallstones which are radioopaque in 10%) and CT abdomen
Amylase and lipase
- Elevated serum amylase and lipase levels, in combination with severe abdominal pain, often trigger the initial diagnosis of acute pancreatitis.
- Serum lipase rises 4 to 8 hours from the onset of symptoms and normalizes within 7 to 14 days after treatment.
- Serum amylase may be normal (in 10% of cases) for cases of acute or chronic pancreatitis (depleted acinar cell mass) and hypertriglyceridemia.
- Reasons for false positive elevated serum amylase include salivary gland disease (elevated salivary amylase) and macroamylasemia.
- If the lipase level is about 2.5 to 3 times that of Amylase, it is an indication of pancreatitis due to Alcohol .
Regarding selection on these tests, two practice guidelines state:
- "It is usually not necessary to measure both serum amylase and lipase. Serum lipase may be preferable because it remains normal in some nonpancreatic conditions that increase serum amylase including macroamylasemia, parotitis, and some carcinomas. In general, serum lipase is thought to be more sensitive and specific than serum amylase in the diagnosis of acute pancreatitis"
- "Although amylase is widely available and provides acceptable accuracy of diagnosis, where lipase is available it is preferred for the diagnosis of acute pancreatitis (recommendation grade A)"
Most (PMID 15943725, PMID 11552931, PMID 2580467, PMID 2466075, PMID 9436862), but not all (PMID 11156345, PMID 8945483) individual studies support the superiority of the lipase. In one large study, there were no patients with pancreatitis who had an elevated amylase with a normal lipase . Another study found that the amylase could add diagnostic value to the lipase, but only if the results of the two tests were combined with a discriminant function equation .
Computed tomography
Regarding the need for computed tomography, practice guidelines state:
- 2006: "Many patients with acute pancreatitis do not require a CT scan at admission or at any time during the hospitalization. For example, a CT scan is usually not essential in patients with recurrent mild pancreatitis caused by alcohol. A reasonable indication for a CT scan at admission (but not necessarily a CT with IV contrast) is to distinguish acute pancreatitis from another serious intra-abdominal condition, such as a perforated ulcer." magnetic resonance imaging (MRI) has become increasingly valuable as a tool for the visualization of the pancreas, particularly of pancreatic fluid collections and necrotized debris. Additional utility of MRI includes its indication for imaging of patients with an allergy to CT's contrast material, and an overall greater sensitivity to hemorrhage, vascular complications, pseudoaneurysms, and venous thrombosis.
Another advantage of MRI is its utilization of magnetic resonance cholangiopancreatography (MRCP) sequences. MRCP provides useful information regarding the etiology of acute pancreatitis, ie, the presence of tiny biliary stones (choledocholithiasis or cholelithiasis) and duct anomalies.
Further Reading
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