Acute Pancreatitis

Acute pancreatitis is a reversible inflammatory process of the pancreas caused by auto digestion that generally presents with epigastric abdominal pain that may radiate to the back and is worsened by the ingestion of food. Acute pancreatitis is often mild, but severe disease can have a mortality rate of up to 30%.  The most common causes are gallbladder disease, alcohol use, and hypertriglyceridemia. In addition to abdominal pain, patients may present with nausea and vomiting, which are nonspecific in most cases, so imaging and laboratory testing are important for definitive diagnosis.  Lipase is the preferred laboratory test for diagnosing acute pancreatitis, as it is the most sensitive and specific marker for pancreatic cell damage.  Additional laboratory testing, such as complete blood count (CBC) and lactate dehydrogenase (LDH) tests, are useful to obtain prognostic information.

Quick Answers for Clinicians

What should be considered in the differential diagnosis of acute pancreatitis?

Abdominal pain, nausea, and vomiting are relatively nonspecific symptoms and may occur in a variety of situations. The differential diagnosis includes but is not limited to acute cholecystitis, appendicitis, cholangitis, intestinal obstruction, gastric volvulus, mesenteric ischemia, nephrolithiasis, pancreatic cancer, perforated ulcer, diabetic ketoacidosis, acute coronary syndrome, aortic dissection, ectopic pregnancy, and tubo-ovarian abscess. Appropriate laboratory testing and imaging are essential to differentiating these conditions.

Which laboratory tests should be ordered when acute pancreatitis is suspected?

The best test for diagnosis of acute pancreatitis is lipase. If lipase is >3x the upper limit of normal, it is highly likely that the patient has acute pancreatitis. Amylase should not be ordered. Although amylase was the original preferred test for acute pancreatitis and is still widely used, it is less sensitive and specific than lipase and provides no additional clinical information.  

What role does imaging play in the diagnosis of acute pancreatitis?

Imaging can contribute to the diagnosis of acute pancreatitis and enable assessment for local complications. The most commonly used modalities are ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), and endoscopic retrograde cholangiopancreatography (ERCP). 

Indications for Testing

Laboratory testing for acute pancreatitis is appropriate to support the diagnosis in patients with suspected acute pancreatitis and to contribute to prognosis.

Criteria for Diagnosis

According to the American College of Gastroenterology clinical practice guidelines, the definitive diagnosis of acute pancreatitis requires two of the criteria in the table below :

Criteria for the Diagnosis of Acute Pancreatitis
Epigastric abdominal pain
Elevated lipase or amylasea concentration >3x upper limit of normal
Imaging findings of pancreatic inflammation

aAmylase measurement is no longer the recommended method for the diagnosis of acute pancreatitis; see the Amylase section for more information.

Source: Banks, 2006 

Laboratory Testing

Diagnosis

Lipase

The best test for acute pancreatitis is the serum lipase test. If the lipase concentration is >3x the upper limit of normal, a diagnosis of acute pancreatitis is highly likely. Serum lipase levels increase within 4-8 hours of acute pancreatitis onset and remain elevated for 8-14 days. Serial measurements are not necessary, as they do not provide prognostic information. The degree of elevation does not correlate with prognosis.  Furthermore, lipase measurement is more sensitive and specific for pancreatic disease than amylase.

Amylase

Amylase measurement is no longer recommended for the diagnosis of acute pancreatitis. Lipase offers improved sensitivity and specificity because amylase is also secreted by other organs.   Serum amylase is initially elevated but returns to normal in 48-72 hours. 

Prognosis

Several systems exist for estimating severity and assessing prognosis of acute pancreatitis, although there is no clinical agreement on which should be utilized. The most widely used systems include the Revised Atlanta Classification, Ranson Criteria Scoring, Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II scale, Glasgow Prognostic Criteria (Imrie Scoring System), and the BALI score. The following laboratory tests are included in at least one of these systems and may contribute to prognosis.   

Complete Blood Count

Leukocytosis and hemoconcentration are common in severe disease. 

Metabolic Panel

A metabolic panel should be considered to inform prognosis and guide treatment decisions. Panels should include sodium, potassium, blood urea nitrogen (BUN), creatinine, calcium, glucose, and bicarbonate to provide information about fluid status. Calcium, BUN, and glucose abnormalities may be relevant for prognosis. Complete metabolic panels that also include albumin, alkaline phosphatase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin may provide information about a possible relation to biliary tract disease.  

Lactate Dehydrogenase

Elevated concentrations of lactate dehydrogenase (LDH) are associated with a worse prognosis in certain clinical circumstances.  

C-Reactive Protein

C-reactive protein (CRP) concentrations >150 mg/dL within the first 48 hours after disease presentation suggest acute necrotizing pancreatitis. To minimize the risk of false-negative test results, CRP should be ordered 48 hours after illness onset. 

Procalcitonin

Procalcitonin measurement may help differentiate between mild and severe disease and should be obtained early in illness.  

Trypsin

Trypsin levels are indicative of pancreatic damage. Concentrations are significantly elevated in acute pancreatitis.  

Interleukin 6

Elevated concentrations of interleukin 6 are associated with a worse prognosis in certain clinical circumstances.

ARUP Laboratory Tests

Diagnosis

Recommended test to establish diagnosis of acute pancreatitis

Prognosis

Panel includes albumin; alkaline phosphatase; AST; ALT; bilirubin, total; calcium; carbon dioxide; creatinine; chloride; glucose; potassium; protein, total; sodium; and urea nitrogen

Medical Experts

Contributor
Contributor

Pearson

Lauren N. Pearson, DO, MPH
Assistant Professor of Clinical Pathology, University of Utah
Laboratory Director for ARUP at University of Utah Health and Huntsman Cancer Institute
Laboratory Director, South Jordan and Sugarhouse Health Center Clinical Laboratories

References