Lipase-amylase ratio does not determine the etiology of acute pancreatitis. Another myth bites the dust.

We examined the feasibility of the lipase-amylase (L/A) ratio to differentiate alcoholic from nonalcoholic acute pancreatitis in a large prospective series of patients with acute pancreatitis. One hundred fifty-eight consecutive patients with acute pancreatitis were studied. The pancreatitis was of biliary origin in 112 patients, due to alcohol abuse in 26, due to other causes in 8, and of unknown origin in 12. For all patients, serum, amylase, and lipase levels were determined simultaneously, and the L/A ratio was calculated using the amylase and lipase serum levels expressed as multiples of the respective upper normal limit. The ratios in patients with alcoholic acute pancreatitis ranged from 0.3 to 8 and in patients with nonalcoholic acute pancreatitis from 0 to 19.9. A value of 2.2 for the serum L/A ratio was found to be the best cutoff value for differentiating alcoholic from nonalcoholic acute pancreatitis. Using this limit, the sensitivity, specificity, and diagnostic accuracy of the L/A ratio in determining the alcoholic form of acute pancreatitis were 54%, 82%, and 77% respectively. Our study showed that the L/A ratio is not useful in distinguishing alcoholic from nonalcoholic acute pancreatitis.