The differential diagnosis of diarrhea includes primary hyperthyroidism, bacillary dysentery, and Crohn’s disease. 1. Primary hyperthyroidism: hyperthyroidism due to exuberant metabolism can also lead to diarrhea, but compared to diarrhea, hyperthyroidism diarrhea patients whose T3, T4 is higher than the diarrhea of the high TSH is lower. There will also be irritability, lethargy, hyperactivity and other clinical manifestations. 2. Bacterial dysentery: when infected with dysentery bacillus, bacillary dysentery will occur, bacillary dysentery will appear diarrhea symptoms, compared with diarrhea, bacillary dysentery can appear mucopurulent blood stool, and there are fever, vomiting, left lower abdominal pain and other symptoms. 3. Crohn’s disease: Crohn’s disease can appear diarrhea symptoms, compared with diarrhea, Crohn’s disease diarrhea is mostly paste-like stool, and may also have the right lower abdominal pain, fever, malnutrition and other clinical manifestations. When the frequent occurrence of diarrhea symptoms may be suspected to be caused by the disease diarrhea, need to be examined in a timely manner.