Narrowly defined renal function tests need to draw blood to check urea, creatinine, uric acid, cystatin C. Broadly defined renal function tests also include urine routine, urine protein quantification, and even renal ECT. Narrow renal function test is to draw venous blood to check urea, creatinine, uric acid and cystatin C. However, in early stage of renal impairment, due to the strong compensatory ability of the kidney, the above indexes may still be normal. Therefore, the broad renal function test also includes other related tests, such as routine urinalysis, 24-hour urine protein quantification and other tests to check the condition of urine protein. The most accurate examination of renal filtration function is renal ECT, which can understand the filtration function of individual kidney. It is better to avoid fever and strenuous exercise before kidney function test, and pay attention to light diet, avoid eating a large amount of high protein food and greasy food, so as not to cause test error. If necessary, consult your doctor about the precautions.