Which of the following is the most specific first-line investigation for acute pancreatitis?

Serum lipase levels are considered the most specific first-line investigation for diagnosing acute pancreatitis. While both lipase and amylase levels can be elevated during an episode of acute pancreatitis, lipase tends to have greater specificity for the condition. Lipase is produced by the pancreas, and its levels remain elevated for a longer duration compared to amylase, making it particularly useful in confirming recent or acute episodes of pancreatitis. In cases of pancreatic inflammation, lipase levels typically rise significantly, which directly correlates with the condition.

Abdominal ultrasound and CT scans are often used to assess complications or underlying causes of pancreatitis, such as gallstones or pancreatic necrosis, but they are not definitive for diagnosing the initial event. Abdominal ultrasound can miss mild cases of pancreatitis and may not effectively capture the enzyme activity. Meanwhile, a CT scan, while informative, is usually reserved for cases where complications are suspected or when the clinical picture is unclear after initial lab evaluations. Thus, while imaging tests are important in the overall management of pancreatitis, serum lipase is preferred as a first-line investigation due to its high specificity.

Amylase levels, although they can also be elevated in pancreatitis, lack the specificity that lipase offers