Quick answer
No single permeability test is perfect. The practical approach is to use the right test for the question and interpret results in context.
Main options
- Lactulose-mannitol: functional barrier signal useful for trend tracking.
- Zonulin: indirect marker that should not be used as a standalone diagnosis.
- Rule-out testing: celiac/inflammatory workup when clinically indicated.
Bottom line: testing helps when it drives decisions, not when it becomes a label.