During routine physical examination, if the blood test suggests normal kidney function, it is still necessary to do ultrasound examination again. The human body has two kidneys, and each kidney has about 1 million renal units, therefore, the compensatory ability of kidney function is very strong; when kidney disease occurs, as long as the damage to the kidney is not too serious, the kidney function can be compensated, and at this time, the kidney function test is also within the normal range, therefore, in order to find out the potential diseases of the kidneys, color ultrasound examination is necessary. Secondly, certain kidney diseases, such as kidney stones, kidney cysts and so on, have a small effect on kidney function, simple examination of renal function can not detect these diseases, and it is necessary to carry out imaging tests such as renal ultrasound to make a clear diagnosis, in order to guide the subsequent treatment. If patients need kidney function tests, it is recommended to go to regular hospitals to have the test results prescribed and evaluated by professional doctors.