Breakfast is not usually recommended for blood tests for kidney function. Generally need to fast for 6~8 hours after the test. Blood test for kidney function mainly includes urea nitrogen, creatinine, uric acid and other related indicators. Creatinine is the metabolic end product of creatine in muscle tissue, if eating more meat, it may lead to higher creatinine level; urea nitrogen is the breakdown product of protein, if eating food such as eggs, milk, etc., it may also lead to higher urea nitrogen level. Therefore, it is usually not recommended to have breakfast when taking blood to check kidney function. If patients need to check their kidney function, it is recommended to go to regular hospitals to have the test results prescribed and evaluated by professional doctors.