The correct answer in this case is passage of a gallstone.
The patient has had weight loss, which increases the risk of gallstone formation, and the pain pattern is consistent with passage of a gallstone through the common bile duct.
I have seen a number of cases where the diagnosis was missed when the lab pattern is similar to the labs in this case. The high transaminases and the absence of significant alkaline phosphatase elevation can be confusing. We are taught in our medical training that alkaline phosphatase is a lab value that goes up with obstruction, and that transaminases are liver injury labs. What are the data on liver labs in the setting of acute obstruction as seen with the passage of a gallstone?
Frederick Kiechle, MD, and colleagues reported that alkaline phosphatase levels, either alone or in conjunction with bilirubin levels, were not useful in determining the presence of common bile duct stones.1 Ming-Hsun Yang et al. found that normal gamma-glutamyl transferase results had the highest negative predictive value for the presence of a common bile duct stone (97%).2 The sensitivity for ultrasound detection of CBD stone in this study was only 35%.
Keun Soo Ahn and colleagues found that, in patients with symptomatic CBD stones, the average AST was 275, and the average ALT was 317 – about six to seven times the upper limit of normal for these lab tests.3 In the same study, the average alkaline phosphatase was 213, which is about twice the upper limit of normal.