The kidney is the main organ of water metabolism in the human body, and once the disease is present, a series of edema symptoms will appear, and the characteristics of edema are different from those of other properties. Generally speaking, edema caused by kidney disease is mostly manifested as follows: 1. edema first occurs in the relaxed parts of tissues, such as eyelids, scrotum or face, and is more obvious when waking up in the morning, and then develops to the ankles, and the edema of the lower limbs is more symmetrical on both sides and spreads to the whole body when serious, and develops more rapidly. 2. edema is soft and easy to move, except for individual cases such as mucinous edema caused by hypothyroidism, most edema is not recovered immediately after pressing the skin with a finger. The site of edema mostly changes with the change of body position, and when the patient is not in bed, the edema is mainly concentrated in the pre-sacral area. In severe cases, ascites and pleural fluid may appear. In addition, edema caused by renal disease is often accompanied by signs of renal disease, such as hypertension, proteinuria, hematuria and tubular urine, and a significant decrease in plasma albumin, etc. It should also be distinguished from hepatic edema, which mostly appears first as ascites and pleural fluid, accompanied by a series of symptoms of liver disease, and cardiac edema, which is mainly caused by circulation, predominantly heart failure, inability to rest in a flat position, accompanied by cardiac enlargement and decreased ejection index. It can be distinguished.