Alanine transaminase rather than abdominal ultrasound alone is an important investigation to justify cholecystectomy in patients presenting with acute pancreatitis.

OBJECTIVES: The aims of this study were to investigate the predictive value of an elevated level of alanine transaminase (ALT) for biliary acute pancreatitis (AP) and to reconsider the role of abdominal ultrasound (AUS).
METHODS: All patients admitted to Christchurch Public Hospital with AP between July 2005 and December 2008 were identified from a prospectively collected database. Peak ALT within 48 h of presentation was recorded. Aetiology was determined on the basis of history, AUS and other relevant investigations.
RESULTS: A total of 543 patients met the inclusion criteria. Patients with biliary AP had significantly higher median (range) ALT than those with non-biliary causes (200 units/l [63-421 units/l] vs. 33 units/l [18-84 units/l]; P < 0.001). An ALT level of >300 units/l had a sensitivity of 36%, specificity of 94%, positive predictive value of 87% and positive likelihood ratio of 5.6 for gallstones. An elevated ALT and negative AUS had a probability of 21-80% for gallstones.
CONCLUSIONS: An elevated ALT strongly supports a diagnosis of gallstones in AP. Abdominal ultrasound effectively confirms this diagnosis; however, a negative ultrasound in the presence of a raised ALT does not exclude gallstones. In some patients consideration could be given to proceeding to laparoscopic cholecystectomy based on ALT alone.