When having blood tests in the morning, after what time in the evening should you stop eating?
Nov 22, 2022
Source: Cainiu Health
Dr. Yang Shuwen
Introduction
Have blood drawn in the morning; do not eat after 10 PM the previous night. For fasting blood tests, avoid food for at least 10 hours, preferably 14 hours. Testing indicators such as blood glucose and liver function under these conditions ensures the quality of the collected blood sample. Eating after midnight the previous night may affect the next day's blood test results.
Blood tests in the morning require fasting after 10 p.m. the previous night.
Fasting for blood draws should last at least 10 hours, preferably up to 14 hours. Testing indicators such as blood glucose and liver function can thus ensure the quality of the collected blood sample. Eating too late the night before may affect lipid levels due to dietary influence. Consuming food after midnight will impact the next day's blood test results. For instance, if liver function, kidney function, or electrolyte tests are scheduled for the following day, eating beforehand could interfere with the laboratory results—especially liver function tests, where transaminase levels may rise after meals. Dietary intake also significantly affects certain serological tests. Some serological tests measure antibodies against multiple viruses; after eating, blood becomes diluted, potentially lowering antibody concentrations and leading to clinically misleading results.
When necessary, it is recommended not only to avoid eating after 10 p.m. the night before blood testing but also to consume a light dinner without overeating.
