Whether a single small kidney affects function needs to be determined whether it is a congenital or acquired factor. If it is a congenital factor, it usually will not affect the function, if it is an acquired factor may affect the function. 1. Congenital factors: congenital factors congenital small kidneys, generally does not affect the function of the kidneys, only one kidney, as long as the kidney function is normal can also meet the function of the body. One kidney is small in size and the other one may increase in size compensatory, some people may have symptoms of fatigue, but it will not have too much effect. 2. Acquired factors: Acquired factors, such as the presence of trauma, tumors and other reasons, the removal of one kidney, need to observe the function of the other kidney, assess the glomerular filtration rate, urine protein quantitative and so on. Patients who do not have factors that lead to kidney function impairment can usually live a normal life; if the patient’s other kidney is also damaged, the function will be affected. It is found that there is only one kidney and the kidney is small, the function of the kidney needs to be assessed, and it is recommended to consult the nephrology department of a regular hospital.