Is fasting required for liver function tests?
Aug 12, 2025
Source: Cainiu Health
Dr. Gao Jun
Introduction
In general, liver function tests require fasting. You should fast for 8-12 hours before the test, during which time you may drink small amounts of plain water, but avoid beverages, tea, or other drinks. On the day before the test, maintain a light diet and avoid alcohol, greasy foods, or spicy foods. On the day of the test, wear loose-fitting clothing to facilitate blood collection. If you are currently taking medications, inform your doctor in advance.
Generally, a liver function test requires fasting. Detailed explanation is as follows:
Liver function tests include various indicators such as bilirubin, transaminase, and albumin, which can be easily affected by food intake. After eating, gastrointestinal motility increases, and the body's metabolic state changes, causing fluctuations in blood fat and protein levels. This may lead to elevated transaminase levels or abnormal bilirubin readings, thus affecting the accuracy of the test results. When fasting, the body remains at its basal metabolic level with relatively stable blood composition, thereby more accurately reflecting the functional status of the liver. Therefore, fasting is required before a liver function test.
You should fast for 8–12 hours before the test, although small amounts of plain water are allowed. Avoid drinking beverages, tea, or other liquids. On the day before the test, maintain a light diet and avoid alcohol, greasy foods, or spicy dishes. On the day of the test, wear loose clothing to facilitate blood collection. If you are currently taking any medications, inform your doctor in advance to determine whether you need to stop taking them. You can resume normal eating after the test and there is no need for excessive dietary restrictions.
