The kidneys are the body’s main organ for excreting water. When the kidneys are diseased, water cannot be excreted from the body and is trapped in the body, it is called renal edema. Oedema is the most common symptom of kidney disease, ranging from eyelid and facial edema in mild cases to generalized edema or hydrothorax and ascites in severe cases. The degree of edema can be mild or severe. In mild cases, there is no visible edema, only weight gain or a slight swelling of the eyelids in the early morning. In severe cases, the edema may be obvious all over the body, even with pleural or abdominal effusion, resulting in weight gain of tens of kilograms (severe edema). The most common would be finger dimple edema, where you see dimples appear when you press down with your finger. Taking a medical history provides information about the etiological analysis, pathogenesis, diagnosis and differential diagnosis, treatment and prognosis of edema. In addition to the general history, patients with edema should be asked about the following: (1) whether they had edema in the past, the development of edema, whether it is persistent or intermittent, and whether it tends to get better or worse; (2) the location of edema, whether it is generalized or limited, and if it is generalized, attention should be paid to the presence of heart disease, kidney disease, liver disease, malnutrition, and internal disease. Liver disease, malnutrition and endocrine dysfunction and other medical history; such as limited is often related to inflammatory infections, trauma, surgery, tumors, vascular disorders and metabolic reactions; ③ whether recently received certain agents or drug therapy, such as large amounts of saline injection, adrenal corticosteroids, testosterone, estrogen and so on. Patients with edema should undergo a detailed systemic examination because many system, organ and tissue disorders can cause edema. A whole-body examination helps to understand the source of edema and its characteristics, and helps in diagnosis and differential diagnosis. Sitting breathing, increased heart rate or pulse, enlarged heart, ventricular systolic or diastolic dysfunction, increased central venous pressure, large venous stasis, jugular vein anger, and enlarged liver and spleen stasis suggest the presence of cardiac failure, and edema is caused by cardiac disorders; enlarged spleen stasis, anger in the lateral circulation veins of the abdominal wall, and portal hypertension combined with ascites suggest cirrhosis; if the expression is sluggish, hair is sparse, and skin is rough, it suggests hypothyroidism. This suggests the possibility of hypothyroidism, i.e., bulbar edema. In addition, patients with liver disease and patients with kidney disease have different expressions in terms of facial appearance and skin pigmentation.