The first characteristic of geriatric diseases is atypical clinical manifestations. Because of the decreased responsiveness of the elderly and the usually milder self-conscious symptoms, the disease manifests itself more insidiously and the clinical manifestations are atypical, which often leads to misdiagnosis and underdiagnosis. For example, severe infections in the elderly can have only a low fever or even no fever. The sensitivity of the elderly to painful stimuli is also reduced, so they may not feel pain during heart attacks, and painful symptoms may be mild during cholelithiasis and appendicitis. The second characteristic of geriatric disease is the coexistence of multiple diseases. An elderly person can have multiple diseases at the same time, such as coronary heart disease and hypertension, as well as chronic bronchitis and prostate enlargement, so the clinical manifestations can be more complicated when they are sick. The third characteristic of geriatric diseases is that they are prone to complications. One of the most common complications is neuropsychiatric complications, such as various degrees of impaired consciousness. The fourth characteristic of geriatric disease is the rapid progression of the disease. Because the stability of various organ functions and the internal environment is reduced in the elderly, the disease can deteriorate rapidly in a short period of time once it occurs.