The answer would be: total bilirubin
Bilirubin is the waste that needs to be dumped by the gallbladder. In chronic cholecystitis, the common bile duct might be obstructed. This leads to increased level of bilirubin, mostly conjugated bilirubin. Pruritus, clay-colored stools, and voiding dark, frothy urine could be caused by hyperbilirubinemia(increased level of bilirubin in the blood).