Fasting Before A Blood Test
In general, it is recommended to fast for at least 8 hours before the blood test, but it depends on the type of test you want to do. We will tell you more about it here.
One of the most widely used medical tests is a blood test because it provides a lot of information about a person’s state of health. So much so that it is considered a routine and basic test for almost any medical procedure.
Blood tests can be used to analyze different parameters. They are often classified according to the suspected diagnosis, although they most often have certain values. For example, the blood sugar level or the number of blood cells.
This test is preferably carried out in the first hour of the morning. It is also recommended to fast, that is, not to have eaten or drunk anything in the past eight hours. In this article, we explain why.
What can a blood test be used for?
A blood test involves taking the patient’s blood and analyzing it in a laboratory. This test can be used to study many different aspects of the body in order to obtain information about the state of health of the organism as a whole or of a particular organ.
A test includes a blood count. It is the concentration of each type of cell in the blood i.e. red blood cells, white blood cells and platelets. It also shows the shape of these cells to see if they are normal.
Likewise, many biochemical values can be studied, such as the concentration of blood glucose or iron. This group also includes cholesterol, triglycerides, thyroid enzymes, urea, etc.
All these parameters are essential for detecting certain pathologies. For example, thyroid enzyme values may indicate thyroid disease. Iron and other related elements help assess anemia.
The blood test can even be used to suspect certain types of tumors. Some of them work by releasing specific substances that can be found in the blood.
Why is fasting important before a blood test?
When planning a blood test, you are asked to go there after fasting for at least 8 hours. This means that you should not eat or drink anything (except water) during the night. This is because food and drinks are absorbed into the blood and can modify certain parameters.
However, this fast is relative and depends on what is tested. For example, if the only thing you want to watch is your blood count, you don’t need to fast. However, in the case of glucose, it takes 8 hours in adults and at least 3 hours in children.
On the other hand, in the case of the thyroid evaluation, a 4 hour fast is sufficient. For cholesterol, it is even advisable to fast for about 12 hours. Another aspect to consider is that of drugs.
Some medicines, as well as food, can affect blood values. The doctor who orders the test is usually aware of this and knows whether or not to stop treatment.
What are the other things to consider?
Health care workers usually make other recommendations to get the blood test done as smoothly as possible. First, besides fasting, you should avoid smoking right before the test. It seems that smoking can also affect blood sugar levels.
You can drink water, but in moderation, to quench your thirst. What is totally contraindicated is to drink alcoholic beverages before the test. It is also not recommended to exercise the night before, as some markers can be confused.
In any case, it is ideal for the doctor to give individual advice. As we have already mentioned, each patient may or may not need to interrupt the medication, or may adapt the fast depending on the aspects to be studied.
