Acute kidney injury is divided into early stage, maintenance stage and recovery stage according to the course of the disease, and the clinical manifestations of each stage are different. For example, there is usually no typical renal manifestation in the early stage of acute kidney injury; in the maintenance stage, there is mainly oliguria and systemic manifestation; in the recovery stage, there is mainly polyuria. In early stage, there is usually no special performance; in maintenance stage, the main manifestations are decreased urine output and systemic symptoms, gastrointestinal symptoms such as nausea, vomiting, abdominal distension, etc., and in severe cases, gastrointestinal bleeding, respiratory symptoms such as respiratory distress, and neurological symptoms such as impaired consciousness, agitation, delirium, etc.; in the recovery stage, the main manifestations are increased urinary output, which can be up to 3,000~5,000 ml per day, or even more. Not all acute kidney injuries have typical manifestations of the above three phases. Some patients may not have oliguria, and depending on the degree of renal function decline, patients may not have typical systemic symptoms. Therefore, it is not possible to judge whether it is acute kidney injury simply based on the above symptoms, and it is necessary to confirm the diagnosis with renal function and other related tests. Patients with acute kidney injury are recommended to go to regular hospitals for timely consultation, complete the examination to identify the cause of the disease, and then give targeted treatment or therapy under the guidance of doctors.