Acute Pancreatitis: Investigations
In addition to confirming the diagnosis, laboratory tests are helpful in defining an etiology and looking for complications.
Serum amylase and lipase levels are typically elevated in persons with acute pancreatitis. Amylase or lipase levels at least 3 times above the reference range are generally considered diagnostic of acute pancreatitis. Serum amylase is however, not specific for pancreatitis. The serum half-life of amylase is short, and elevations generally return to reference ranges within a few days. |
EtiologyPathophysiologyHistoryPhysical ExaminationInvestigationsDifferential DiagnosisManagementClinical ScenariosAnswers |
Lipase has a slightly longer half-life and abnormalities may support the diagnosis if a delay occurs between the pain episode and the time the patient seeks medical attention. Elevated lipase levels are more specific to the pancreas than elevated amylase levels. Lipase levels remain high for 12 days. In patients with chronic pancreatitis (usually caused by alcohol abuse), lipase levels may be elevated in the presence of a normal serum amylase level.
Elevated alkaline phosphatase, total bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) provide evidence of gallstone pancreatitis.
C-reactive protein (CRP) is an acute-phase reactant that is not specific for pancreatitis. A value can be obtained 24-48 hours after presentation to provide some indication of prognosis. Higher levels have been shown to correlate with a propensity toward organ failure.
Measurement of blood urea nitrogen (BUN), creatine, and electrolytes should be done as a great disturbance in the electrolyte balance is usually found, secondary to third space loss of fluids. Blood glucose level may be elevated from B-cell injury in the pancreas.
Measurement of calcium, cholesterol, and triglyceride levels should be done to search for an etiology of pancreatitis (eg, hypercalcemia or hyperlipidemia) or complications of pancreatitis (eg, hypocalcemia resulting from saponification of fats in the retroperitoneum).
Elevated alkaline phosphatase, total bilirubin, aspartate aminotransferase (AST), and alanine aminotransferase (ALT) provide evidence of gallstone pancreatitis.
C-reactive protein (CRP) is an acute-phase reactant that is not specific for pancreatitis. A value can be obtained 24-48 hours after presentation to provide some indication of prognosis. Higher levels have been shown to correlate with a propensity toward organ failure.
Measurement of blood urea nitrogen (BUN), creatine, and electrolytes should be done as a great disturbance in the electrolyte balance is usually found, secondary to third space loss of fluids. Blood glucose level may be elevated from B-cell injury in the pancreas.
Measurement of calcium, cholesterol, and triglyceride levels should be done to search for an etiology of pancreatitis (eg, hypercalcemia or hyperlipidemia) or complications of pancreatitis (eg, hypocalcemia resulting from saponification of fats in the retroperitoneum).
Ransons Criteria
At admission Age > 55 years
WBC > 16000 cells/mm3 Blood Glucose > 10 mmol/L Serum AST > 250 IU/L Serum LDH > 350 IU/L |
At 48 hoursCalcium < 2 mmol/L
Haematocrit fall >10% PO2 < 60 mm Hg BUN increase>/= 1.8 mmol/L Base deficit >4 mEq/L Fluid Sequestration >6L |
Score >/= 3 indicates severe pancreatitis
Modified Glasgow Criteria
Glasgow prognostic score: (Note PANCREAS Acronym)- PaO2 < 8kPa (60mmhg)
- Age > 55 years
- Neutrophils: WBC >15 x109/l
- Calcium < 2mmol/l
- Renal function: Urea > 16 mmol/l
- Enzymes: AST/ALT > 200 iu/L or LDH > 600 iu/L
- Albumin < 32g/l
- Sugar: Glucose >10mmol/L
Score >/= 3 indicates severe pancreatitis
APACHE II
The APACHE score has the advantage of being able to assess the patient at any point during the illness; however, it is very cumbersome for routine clinical use. Attempts have been made to make this evaluation user friendly (eg, with APACHE II, the Simplified Acute Physiology Score [SAPS], and the Imrie score), but it remains cumbersome. The sensitivity is 77%, and the specificity is 84%.
Imaging
- Abdominal X ray
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- Ultrasound Abdomen
- CT scan
Abdominal CT scans also provide prognostic information based on the following grading scale developed by Balthazar et al.
Grade A - Normal pancreas
Grade B - Focal or diffuse gland enlargement (see the image below)
Grade C - Intrinsic gland abnormality recognized by haziness on the scan
Grade D - Single ill-defined collection or phlegmon
Grade E - Two or more ill-defined collections or the presence of gas in or nearby the pancreas
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ERCP
ERCP used to evaluate the biliary and pancreatic ductal system and is indicated in a subset of patients with acute pancreatitis. It should be performed only in the following situations:
- The patient has severe acute pancreatitis that is believed, and is seen on other radiographic studies, to be secondary to choledocholithiasis
- The patient has biliary pancreatitis and is experiencing worsening jaundice and clinical deterioration despite maximal supportive therapy.
When combined with sphincterotomy and stone extraction, ERCP may reduce the length of hospital stay, the complication rate, and, possibly, mortality.
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