Is fasting required for a liver function test?

Food can influence some blood measurements, while liver enzymes and bilirubin are interpreted as part of a wider pattern. The laboratory may therefore give different instructions depending on the tests being performed. Water is often treated differently from food, but you should confirm this locally. People with diabetes, pregnancy or medicines that must be taken with food need an individual plan.

Check the appointment message or call the laboratory before changing what you eat or drink. Ask whether plain water is allowed, when to take regular medicines and what to do if you accidentally eat. Bring a medication and supplement list. Do not skip essential medicine or extend a fast beyond the stated instructions. If fasting makes you faint, tell the staff before sampling.

Contact the ordering clinician before fasting if you have diabetes, a history of fainting, a condition affected by missed meals or a medicine that requires food. Seek urgent help for severe weakness, confusion, collapse, repeated vomiting or yellowing of the eyes. These symptoms are not explained simply by whether you fasted.

Was fasting requested for my liver panel or for another test taken at the same visit? May I drink plain water? Should I take my morning medicines? What should I do if I have already eaten?