It is better not to check kidney function after eating. Blood kidney function contains urea nitrogen, creatinine, β-microglobulin, uric acid and other examination items, urea nitrogen has a greater relationship with diet, especially high protein diet has a greater impact on urea nitrogen. If a high protein diet such as eggs and milk is consumed on the same day, it increases the metabolic waste containing nitrogen, which increases the metabolic burden of the kidney and causes an increase in the glomerular filtration rate, which can make the urea nitrogen value rise and affect the result, making the clinician make an error in the judgment of the disease and may cause a false positive result that the kidney function is impaired. Therefore, it is recommended to check kidney function on an empty stomach, and it is recommended to fast for 8-12 hours, during which time do not drink and eat.