How long should one fast before a complete biochemical panel?
Nov 24, 2025
Source: Cainiu Health
Dr. Huang Yuhong
Introduction
The comprehensive biochemical panel includes multiple indicators such as blood glucose, blood lipids, liver function, and kidney function. After eating, the digestion and absorption of food can lead to increased levels of glucose, triglycerides, and other components in the blood, affecting the accuracy of test results. For example, postprandial blood glucose may temporarily rise to more than twice the upper limit of the normal range, and lipid test results may deviate from true levels due to dietary fat intake.
Generally, an 8-12 hour fast is required before undergoing a complete biochemical panel, with the specific duration subject to adjustment based on the tests being performed and hospital requirements. If any abnormalities occur, prompt medical consultation is recommended. Detailed explanations are as follows:
The comprehensive biochemical panel includes multiple indicators such as blood glucose, lipid profile, liver function, and kidney function. After eating, digestion and absorption of food can elevate levels of substances like glucose and triglycerides in the bloodstream, thereby affecting test accuracy. For example, postprandial blood glucose may transiently rise to more than twice the upper limit of normal, and lipid test results may deviate from true values due to dietary fat intake. Therefore, most hospitals require fasting for 8–12 hours prior to testing to ensure that results accurately reflect baseline metabolic status.
For certain specialized tests, the fasting period may be extended. When measuring hormone levels such as gastrin or insulin, or when performing a glucose tolerance test, fasting for more than 12 hours might be required. Patients with conditions affecting gastric emptying, such as diabetes or gastroparesis, should adjust their fasting duration according to medical advice to avoid hypoglycemia or gastrointestinal discomfort caused by prolonged fasting.
On the day before the test, avoid high-fat and high-sugar foods. On the morning of the test, small amounts of water are permitted, but sugary beverages or milk should be avoided. If symptoms of hypoglycemia such as dizziness or palpitations occur during the fasting period, inform healthcare personnel immediately and consume an appropriate amount of sugar if needed.
