Which enzyme is likely to be mildly increased in obstruction?

In cases of obstruction, alkaline phosphatase is the enzyme that is likely to show a mild increase. Alkaline phosphatase is primarily associated with the liver, bones, and bile ducts. When there is an obstruction in the biliary system, it causes bile to back up in the liver, which stimulates the production of alkaline phosphatase and leads to its elevation in the bloodstream. This enzyme serves as a key marker in diagnosing and monitoring liver and biliary conditions.

In contrast, while bilirubin can increase significantly with biliary obstruction, alkaline phosphatase is typically more sensitive to mechanical obstruction of bile flow, especially in early stages. Serum albumin reduction is usually more indicative of chronic liver disease rather than acute obstruction. ALT, primarily a marker for hepatocellular injury, may not show elevation solely due to obstruction without significant liver damage.

Therefore, an increase in alkaline phosphatase highlights the body's response to an obstructive process in the bile ducts, making it the most relevant enzyme to consider in this context.