Blood Tests on Fasting: Things to Do and Don’t

By | November 12, 2019
Blood Tests on Fasting
Blood Tests on Fasting

Have you recently been prescribed with some blood tests by your doctor? Blood tests are highly reliable to make accurate diagnosis fast and easily. These tests provide an accurate diagnosis for a wide range of medical conditions or diseases for people of every age. A large variety of blood tests is there to diagnose different diseases and different tests involve different requirements and different sets of instructions for patients.

For example, certain types of these tests require you to be fasting before giving the blood sample. Why fasting is necessary to conduct certain types of blood tests whereas others do not? Let’s explore the reason in the following paragraph.

Why certain blood tests require fasting?

When you are eating, the food goes into your digestive tract and is gradually absorbed by the overall system of your body. This changes the state of your body organs. This happens every day starting with after you’ve eaten your breakfast. Certain kinds of blood tests require getting accurate results so that your doctor can prescribe the right treatments to facilitate your fast recovery.  So it is important that you fast at least a few hours before giving your blood sample for screening. This is how the foods you’ve eaten do affect neither the organs nor the blood counts. The test results will come perfect and both your treatment and recovery will be facilitated.

In the following paragraph, let’s see which tests require you to fast.

Which are the blood tests that require you to fast?

 While giving your blood sample for the following tests, it’s important that you be on fast:

  • Screening for lipid profile, cholesterol, and triglyceride
  • Blood glucose level test
  • Test for glucose tolerance
  • Liver function test
  • Screening for lipoprotein panel
  • Metabolic panel
  • Kidney function test

In addition to the tests mentioned above, certain vitamin tests will also require you to be on fasting. However, it is important to note, apart from the tests mentioned in this section, more specific blood tests do exist for more advanced diagnostic procedures that also require you to be on fast. If you have to take those tests, your doctor or the concerned lab will give you the necessary instructions beforehand.

Things to do while you’re fasting for a blood test

When you’ve been told to be on fast before a blood test in London, you should better follow the instructions below:

  • Ask your doctor or healthcare provider to give you well-defined instructions and follow them diligently.
  • Be sure about how long you must be on fast before the test.
  • Ask the doctor if you can take the regular medicines while fasting.
  • Take occasional sips of plain water before giving your blood sample.

In case, you’ve accidentally cut anything with your teeth, inform the pathologist as soon as you can.

Things not to do while you’re fasting for a blood test

  • The first thing in this category is you should not over fast. The usual fasting limit for blood tests is 8 to 12 hours. There’s no point in fasting more than that.
  • Avoid caffeine, smoking, alcohol and chewing gums before a blood test as these substances can change the state of the internal organs of your body.
  • Avoid exercising before a blood test on fasting. It will lower the glucose level in the body.  

The doctors will calculate triglycerides after fasting as the concentration of fatty particles get elevated in the bloodstream for several hours after you have the meal. The healthy range of triglycerides is not more than 150 milligrams each deciliter (mg/dL) after the fast of say, 10 to 12 hours.

It is extremely important to get an accurate triglyceride test as the doctors use this number to work out the level of LDL or bad cholesterol. When you do not fast before a standard lipid panel blood test, then this will throw off LDL and triglyceride numbers. On the contrary, eating won’t affect the measurements of total cholesterol and HDL (good) cholesterol to a significant level.

When you do fasting for the blood tests, you can still drink water, black tea or plain coffee. Don’t forget to take the medications regularly unless you have been told to take them with your food only.

The instructions discussed above come from experienced doctors associated with a renowned clinic for private blood tests in London. You should better follow the instructions to ensure accurate test results. Please feel free to contact us for more information on the relevant topic.