Fasting Before Taking A Blood Test: Is It Safe? Here's What The Expert Says

Fasting before blood test is quite common, know if it is necessary and conditions that could influence it. 

Written by: Puru Bansal Updated at: 2022-05-05 16:05

Have you ever gone to a blood test and doctor has told you to go empty stomach? Majority of you will remain affirmative to this. Blood tests are very important for your body and health, it determines your parameters which stabilize your functions. Blood test is important in order to make sure your vitals are in place or determine if there is any discrepancy. Food or beverages could impact your blood level and reading; thus, it is advised not to eat anything before getting a blood test done. Today we will discuss about fasting before getting a blood test done, is it necessary and how does it impact your body. 

What is Blood Test? 

Many people do take blood test, but they are unaware of the condition about why these tests are conducted. We have Dr. Sumeet Nigam, General Physician at Sahara Hospital, Lucknow to tell us about blood test and eating patterns before it. He said that blood tests are used to examine the cells, chemicals, proteins and other substances that are present in the blood. It also helps to understand how the blood is working and common type of lab tests are used to determine the following- 

  • Helps to diagnose diseases and conditions 
  • It is used to monitor chronic conditions such as diabetes and high cholesterol 
  • In order to find out treatment for a disease is working or not. 
  • Keep check on if all organs are working well 
  • Helps to diagnose bleeding and clotting disorders. 
  • It helps to determine if there are any trouble in immune functions in the body 

How to prepare for a Blood Test? 

Not all blood tests will require you to fast from beforehand. But in most cases where people take blood test doctor instructs you to not eat anything or drink any beverages. You can only take water before going to the test. Fasting before certain blood tests are important in order to make sure that tests are accurate. Fasting is only required up to a few hours before the test is done. In most condition, Doctor advises you not to eat anything for 8 to 12 hours prior to the blood test. The vitamins, minerals, fats, carbohydrates and protein that are present in food and beverages can cost you wrong and manipulated readings.  

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Blood tests Without Fasting 

As told earlier by expert, not all blood tests would require you to fast from beforehand. Here are the list of blood tests that you can even have without fasting. 

  • Blood glucose test 
  • Liver function test 
  • Cholesterol test 
  • Test for triglyceride levels 
  • High density Lipoprotein level test 
  • Renal functional panel 
  • Basic metabolic panel 
  • Lower density Lipoprotein level test

In some of these tests, you may not require to fast but still would be told to have limited amount of calories in the diet. Some tests, such as fecal occult blood test, just require to have limited food intake before the test. Red meats, broccoli, and medications could even give false positive blood test. Therefore, it is always advised to follow doctor’s advice before getting a blood test done.  

How long Should you fast before a blood test?

The amount of time that requires for fasting depends on the test. For most tests, you would not be able to consume anything but water for about 8 hours prior to the test. However, in some tests this period of fasting could go up to 12 hours. You can only have plain water, without adding anything extra to it. 

Can you drink coffee while fasting before blood test? 

The answer is no, you cannot. If you drink black coffee or any type of coffee, or it could interfere with your blood test result. Coffee contains caffeine and soluble plant matter, which might skew your result test. It is also diuretic, which means it could increase your urine. This could lead to dehydrating effect on the body which could impact your veins during the test. It could become hard to locate your veins before making a stressful situation.  

Also Read- Why Is Blood Pressure Important And Its Relation With Heart Health, Explains Cardiologist Dr Dora

Can you drink alcohol before a blood test?

It is strictly not advisable to drink alcohol before getting a blood test done. In fact, in some cases Doctor would advise you not to take alcohol for at least 24 hours before the test. This is specially for liver health or triglyceride levels in the blood test. If there are any traces of alcohol that remain in your bloodstream, it could impact your blood test results. Therefore, it is important to discuss with your doctor before scheduling a blood test. 

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