Is it necessary to fast before a routine blood test?

Generally speaking, blood routine examination is a commonly used clinical test. It mainly determines whether there is infection, anemia, or hematologic system diseases in the body by observing the quantity and morphological changes of blood cells such as red blood cells, white blood cells, and platelets. These indicators are usually not affected by food intake or drinking; therefore, fasting is not required before a blood routine examination. The specific explanation is as follows:

Although fasting is not necessary before a blood routine test, to ensure accurate results, it is advisable to avoid consuming overly greasy or high-protein foods before the test and to drink water in moderation. Consumption of excessively fatty or high-protein foods should be avoided prior to the test, as these foods may affect blood composition, potentially leading to conditions like chylous blood, which can compromise the accuracy of the test results. Additionally, excessive water intake may lead to blood dilution, causing inaccuracies in the results. Intense physical activity and extreme fatigue can cause a physiological increase in white blood cells, which may also affect the accuracy of the test.

Before undergoing a blood routine examination, it is recommended to maintain a light diet, eat in moderation, and stay relaxed, avoiding excessive tension and anxiety. Furthermore, strenuous exercise and overexertion should be avoided.