Bangkok: The Council of Medical Technology has confirmed that patients having blood drawn can drink plain water as normal; it will not affect the results of medical laboratory analyses.
According to Thai News Agency, the announcement comes amidst a social media debate on whether it is necessary to fast before having blood drawn. Previously, it was widely believed that "both food and water must be avoided." While many doctors have clarified that drinking plain water is acceptable and even beneficial for saturating the blood vessels, confusion persists. Some patients report that hospitals still instruct them to fast entirely before blood draws, prompting the Medical Technology Council to issue a clarification for hospitals to standardize their practices.
Recently, the Facebook page of the Medical Technology Council addressed a misunderstanding stemming from appointment slips and instructions from some medical facilities that advised patients to "refrain from eating and drinking" before blood drawing. This has led to the misconception that plain water must also be avoided, similar to other food and beverages.
The Council of Medical Technology aims to clarify the scientific information: Plain water is safe to drink as usual. It refers to pure water without color, taste, calories, or additives and will not significantly affect the results of medical laboratory analyses requiring fasting conditions.
Abstaining from water does not offer any benefit and may negatively impact test results. Water deprivation can lead to blood thickening, resulting in inflated laboratory values and making blood collection more difficult, inconvenient, and risky for the patient. Furthermore, reference values for laboratory tests are generally set under fasting conditions but with water allowance. Combining water deprivation with fasting could result in inaccurate test outcomes.
The Council of Medical Technologists urges medical facilities to revise their communication to state, "No food or beverages of any kind are allowed, except plain water, which can be consumed normally." Accurate communication prior to analysis is crucial in improving the quality of medical laboratory test results and ensuring patient safety.