How Long To Fast Before A Blood Test

How Long To Fast Before A Blood Test ?

If you have been asked to fast before a blood test, then you will be wondering how long to fast. As there are many kinds of blood test, so the duration of fasting also varies based on the kind of blood test a person has.

There is a reason why doctors ask patients to fast. When a person eats anything, the chemical balance as well as the biochemistry of the blood alters. For instance, when a person eats food, it gets digested into vitamins, minerals, glucose, water and waste materials. The ones that are important are absorbed by the stomach and intestines, and some of the nutrients like lipids and glucose are released into the blood stream. Hence, this is the reason why the lipid and sugar levels are high in the blood after a person eats. So, if a person is being checked for blood sugar or having a lipid profile done, then the person should not consume any food prior to the blood test as it will spoil the test results and give wrong readings. This will cause the doctor to misdiagnose whether a person is diabetic or suffering from a heart ailment.

So, how long to fast before a blood test? Usually, the fasting time is determined by the test that is going to be conducted. However, in general, patients are advised to fast for a period of eight hours. Also, the fasting period usually does not go beyond twelve hours. It is important to note that when a doctor has asked a person to fast, the person should check with the doctor the period of fasting in case he or she has not be told of the same. Also, some tests allow the person to drink water during the fasting period, while others will strictly stipulate that not even water should be consumed. This is seen when a person is going to have a blood test done for cholesterol. In such a case, the person will be told to fast for a period of six to twelve hours without drinking or eating anything. As it is difficult to fast for such a long time without eating or drinking, usually the blood test for cholesterol is done in the mornings after a person wakes up as the fasting period tends to coincide with the nighttime sleep.

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How Long To Fast Before A Blood Test