Fasting is not required for kidney function tests, and a normal diet is sufficient. However, it is recommended to eat a light diet for two days before the health check, and avoid large amounts of protein and fat intake. Because a lot of exercise and protein intake will affect the level of urea nitrogen and creatinine in the body, some patients may experience a transient increase. Tests that require fasting include checking liver function, fasting glucose and ultrasound of digestive system, abdominal CT, abdominal enhancement CT, etc., mainly related to digestive system. And tests related to kidney, including ultrasound, need to hold urine. Kidney function includes checking urea nitrogen, creatinine, uric acid, and further urological ultrasound and urinary routine are recommended to fully evaluate the kidney condition.