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Fasting Before Blood Tests
Fasting Before Blood Tests

Fasting Before Blood Tests

If your doctor ordered you to take a test that requires fasting, ensure you do not eat or drink anything besides water as this will affect your test result and give a false reading. It may be tempting to eat a little or even take a cup of coffee, but try not to.

When your doctor tells you to come fasting for a private blood test, it means you would not eat or drink anything asides water for 8 – 12 hours before your test. So, if you are supposed to get your test by 8am, and you need to fast for eight hours, it means you can’t take anything after midnight, but if it is a 12-hour fast, you shouldn’t take anything after 8pm.

The fasting includes not taking chewing gum, avoiding exercise and smoking because these things affect your digestion and your test result. The doctor will tell if you can take your prescription medication before the test, but ensure you ask your doctor about taking over-the-counter medications.

What tests Require Fasting?

The result of blood tests tells the doctor whether or not a person hascertain health issues. They also help the doctor know how the body is functioning and how well a treatment is working. Some tests do not require you to fast beforehand, so your doctor will tell you when you need to fast before any blood test.

Fasting blood tests include the following.

  • Fasting blood glucose (FBG)

FBG test measures the amount of sugar (glucose) in the blood to help diagnose diabetes or pre-diabetic conditions. Typical time required to fast is at least eight hours.

  • Lipid profile

Lipid profile helps to determine the level of blood fats like cholesterol. Having high levels of these fats puts you at a high risk of having a stroke or heart disease. The test usually requires about 9 – 12 hours of fasting.

  • Comprehensive or basic metabolic panel

It is usually a part of routine physical exams, and it checks for electrolytes, fluid balance, kidney function, liver function, and blood sugar. It usually requires a fasting time of 6 – 8 hours.

  • Iron tests

Iron test checks for iron levels in the body and the required fasting time is 12 hours.

  • Gamma-glutamyl transferase (GGT)

It checks the GGT enzyme level in the body. If the result is high, it may be because of alcohol abuse, liver disease or bile duct problems. It requires about eight hours of fasting. Your doctor may tell you to stop taking alcohol and some prescription medication for a certain period before the test, so, you would have an accurate test result.

Why is Fasting Necessary?

Fasting is necessary because the nutrients in the food and water you take will get absorbed into the bloodstream, which affects the test result. For example, eating before a fasting blood glucose test supplies your body with more blood sugar, which gives a higher reading. Fasting helps give a baseline result which provides the doctor with an idea of your accurate sugar level for a certain period.

What if I do not fast?

If you eat or take any drink besides water, ensure you tell the person who will draw your blood. This will help the doctor interpret your result correctly, but you may need to reschedule the test for a more accurate reading.

When can I take food or a drink?

The fasting is over after your blood sample collection, so you can bring a snack and drink to eat immediately after your test.

You can get any of your fasting blood test done at Medical Express Clinic. Schedule an appointment today for your test or visit us at https://www.medicalexpressclinic.co.uk/private-blood-tests-london-harley-street for more information about a fasting blood test.