People have two kidneys, located in the posterior part of the abdomen, on either side of the spine, one on the left and one on the right. Patients with congenital developmental defects may have only one kidney, but kidney function is not necessarily abnormal and normal physiological activity can usually be maintained. Patients who have one kidney removed for disease reasons can also maintain normal kidney function by paying attention to protecting kidney function. In a normal person, there are two kidneys, the left kidney is located between the lower edge of the 11th thoracic vertebra and the 2nd-3rd lumbar intervertebral disc; the right kidney is extruded by the liver and is located slightly lower than the left kidney, with the upper edge flush with the lower edge of the 12th thoracic vertebra approximately flush with the upper edge of the 3rd lumbar vertebra. The kidney mainly excretes metabolic wastes, harmful substances and excess minerals and water from the body in the form of urine; at the same time, it returns some of the filtered beneficial substances to the blood through reabsorption to prevent the loss of beneficial substances, so that metabolism can be carried out normally. The kidneys also have certain endocrine functions, which can produce hormones to promote red blood cell production, regulate calcium and phosphorus metabolism, and maintain the stability of the internal environment. Some people have only one kidney due to congenital developmental defects, and one kidney is removed due to an acquired disease. These people can usually maintain normal physiological activities, but the burden of a single kidney is greater, making it difficult to take on heavier physical activities, and also posing certain health risks. Therefore, it is recommended that this special group of people undergo regular tests of kidney function and urinary routine to monitor the health status of individual kidneys.