What is the best initial test to evaluate suspected acute pancreatitis?

In the case of suspected acute pancreatitis, the best initial test to evaluate the condition is measuring serum amylase and lipase levels. Both amylase and lipase are pancreatic enzymes that are typically released into the bloodstream when the pancreas is inflamed.

While serum amylase can be elevated in a variety of conditions, lipase is more specific to pancreatic injury and tends to remain elevated longer than amylase, making it a crucial marker in diagnosing acute pancreatitis. Elevated levels of these enzymes can often confirm the suspicion of pancreatitis, especially when taken alongside the patient's clinical presentation, such as severe abdominal pain and history of gallstones or alcohol use.

Imaging tests like CT scans and MRIs are useful for confirming the diagnosis of pancreatitis or for assessing complications (like necrosis or abscess) but are generally not the first steps in the evaluation. These imaging modalities may be indicated later in the clinical course or if there is concern for complications. Serum bilirubin can provide information about the liver and biliary tree but is not diagnostic for pancreatitis itself.

Thus, measuring serum amylase and lipase is the most effective and practical first step in evaluating suspected acute pancreatitis.