A 73-year-old woman is evaluated for obstructive jaundice after an injury to the CBD, 7 months previously at laparoscopic cholecystectomy. The alkaline phosphatase is elevated. In obstructive jaundice, which of the following statements is true regarding alkaline phosphatase?
High-Yield Explanation
Alkaline phosphatase level usually is more sensitive than the bilirubin level for indicating cholestatic jaundice. It also is more likely to fall before the bilirubin level when the obstruction has been relieved. If an unexplained alkaline phosphatase elevation exists (even in the presence of a normal bilirubin), biliary pathology must be excluded. Elevation of the alkaline phosphatase from a possible source in bone disease can be excluded by measuring isoenzymes.