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Do we have to stop drinking “water” before having a blood test?

Do we have to stop drinking “water” before having a blood test?

Answer: We don’t have to if it’s pure drinking water.

It all started with a familiar conversation.

Customer: Hello, Miss. Can I have a blood test real quick? I’m very thirsty. Haven’t eaten or drink anything since last night, not even water.

Medical Technologist: It is okay for you to drink water, Sir/Madame. Drinking water is always allowed (1st time.)

Customer: Oh… you mean I can take a sip?

Medical Technologist: You can drink water as usual, not just taking a sip (2nd time.) If it’s pure drinking water, no other mixture, such as tea or coffee, you can drink it. This will prevent you from being thirsty. Also, your blood will not be too thick or viscous, which will make the venipuncture easier. If you get too dehydrated, it might even cause some examination inexact. It is good if you plan to have urine test also, so you don’t have to try too much when taking a leak, which is a common problem.

Customer: If that is the case, how come this and that hospitals always told me to refrain from eating and drinking water? What is the explanation behind that?

Medical Technologist: If you will have an examination for diabetes or cholesterol, then it is a requirement that you refrain from eating and drinking for at least 12 hours. However, if it is pure drinking water, you can drink it as usual (3rd time.)

Customer: Oh… you sure there won’t be any problem? If that is the case, then I will drink some water next time (However, many customers still refuse to do so, as they afraid there might be some problems, and they won’t be able to have a blood test.)

This is a common conversation being seen every day in the clinic or hospital. It may be before having the blood test or after getting the result and saw some abnormality. This article is meant to set a clear understanding for those who want to have a health check-up or need to have one for further treatment at the hospital. This will give a clear understanding of how to prepare yourself before having a blood test. It’s already very hard for those who have a congenital disease or need to have breakfast (mostly in the elderly) to refrain from eating; not to mention drinking water. Refraining from drinking or eating for too long may even worsen such congenital disease. The misunderstanding information about this still being seen online everywhere. Therefore, with our most sincerity, we want you to understand this correctly. We are very certain that this article will be useful to many readers, especially those who have health check-up frequently and those who are considering to have one.

If you are curious about our source of information, kindly refer to Siriraj Hospital website as follows: website or Facebook


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