Does drinking water before a physical examination affect liver function testing

Drinking a small amount of water before a physical examination usually does not affect the results of liver function tests, but drinking a large amount of water may dilute the blood and cause slight fluctuations in indicators. The liver function test mainly includes indicators such as alanine aminotransferase, aspartate aminotransferase, total bilirubin, etc. Its accuracy is less affected by diet and drinking water, but extreme drinking behavior should be avoided. The fasting state required for routine physical examination mainly focuses on food intake, and moderate drinking water will not significantly interfere with the detection of liver metabolic enzymes. The human blood volume is relatively stable, and after drinking 200-300 milliliters of water, the changes in blood composition are within the normal physiological regulation range. Liver function indicators reflect the long-term functional status of liver cells, and the impact of brief water intake on key parameters such as transaminase is limited. Maintain a normal amount of water intake at night before the examination, and take a sip of water in the morning to relieve thirst. However, drinking more than 500 milliliters of water in a short period of time may cause temporary blood dilution, especially concentration dependent indicators such as albumin and total protein may appear falsely low. Excessive drinking of water by some sensitive individuals may cause changes in blood osmotic pressure, indirectly affecting the activity detection of enzymes such as alkaline phosphatase. During special liver function tests such as indocyanine green test, it is necessary to strictly follow medical advice and avoid drinking water. 24 hours before the physical examination, one should maintain a normal daily routine, avoid alcohol and high-fat diet, and drink a small amount of water after urination in the morning. If abdominal ultrasound examination is required simultaneously, complete fasting and water deprivation are necessary. Patients with abnormal liver function should maintain the same drinking water status as the previous examination during follow-up to ensure comparability of results. After examination, if abnormal indicators are found, it is recommended to consult a specialist and conduct a comprehensive evaluation based on other tests.