Unusually high alkaline phosphatase due to intestinal isoenzyme in a healthy adult.

Intestinal alkaline phosphatase (ALP) is more prevalent in individuals of blood group O or B, and increases after a meal, especially on a high-fat diet. We did not realize that clinicians could underestimate the importance of fasting for ALP measurement until one healthy adult showed a huge difference in ALP levels before and after a meal. We report a case of transient hyperphosphatasemia resulting in unnecessary workup due to intestinal ALP in a healthy adult of blood group O.