Adults can determine whether lactose tolerance is present through clinical manifestations, laboratory tests, and genetic sequence tests. It is recommended to go to a regular hospital for relevant examinations to make a clear diagnosis. 1. Clinical manifestations: Lactose intolerance in adults is due to the lack of lactase enzyme. When an adult ingests lactose, the body will be unable to digest lactose in time due to the lack of lactase enzyme, resulting in bloating, diarrhea and other uncomfortable symptoms. 2. Laboratory tests: Adults can undergo lactose tolerance test, lactose hydrogen breath and other laboratory tests in the hospital to make a clear diagnosis. 3. Genetic sequence test: When the clinical manifestations and laboratory tests cannot be clarified, adults can be examined to see if there is a genetic sequence defect. If you want to prepare to determine whether lactose tolerance, it is recommended to go to the hospital in time, according to the doctor’s advice, improve the relevant examination, can be clearly diagnosed.