Lipase amylase ratio in acute pancreatitis: An aetiological index?

Objective: To verify if a lipase:amylase ratio greater than two discriminates alcoholic from non-alcoholic acute pancreatitis. The lipase:amylase ratio is calculated by using the amylase and lipase levels obtained on admission and expressed as multiples of the upper normal limit in each case. Design: Retrospective and prospective studies. Setting: Surgical intensive care and gastroenterology units of a university hospital. Patients and measurements: On admission, we calculated the lipase:amylase ratio of 51 patients hospitalized in our intensive care or gastroenterology units for acute pancreatitis during the past 3 years. We then progressively determined the lipase:amylase ratio of 32 consecutive patients who underwent endoscopic retrograde cholangiopancreatography (ERCP). The lipase:amylase ratio was calculated 5 h and 1 day after ERCP when enzyme levels were increased. Results: In the retrospective study, the lipase:amylase ratio was greater than two in 10 out of 11 patients with alcohol abuse-induced acute pancreatitis and in 24 out of 40 non-alcoholic patients. Considering a ratio greater than two as indicative of alcoholic pancreatitis, the sensitivity of this test was 91%, the specificity was 40% and the positive predictive value was 29%. In the prospective study, serum amylase and lipase levels were raised in 20 patients 5 h after ERCP. Fifteen out of the 20 patients had lipase:amylase ratios greater than two, including three patients with abdominal pain. One day after ERCP, enzyme levels returned to normal in 13 patients. Two out of the seven patients who still had increased enzyme levels had lipase:amylase ratios of greater than two. Conclusion: We do not recommend the use of lipase:amylase ratio as a discriminatory index between alcoholic and non-alcoholic acute pancreatitis.