Fasting Rules for Blood Test

When undergoing a blood test, fasting rules for blood test should be followed diligently. The following article will cover some of the blood test fasting rules that will help you prepare for a blood test...
There are many medical conditions for which one needs to undergo a blood test. Fasting rules for blood test are advised by the doctor, wherein one needs to remain without eating food for a certain period. The minute one is told to give their blood for further tests, everything draws a blank in the mind. A needle pricking through the arm, used to draw out blood tends to become a chilling site for many patients. Thus, one tends to mix up the rules for fasting before blood test. There is a lot of confusion about what should be and what should not be done before a fasting blood test. If you too are confused about the blood test fasting rules, then you will find some help from the following paragraphs.

Reasons for Rules for Fasting Before Blood Test
There are many kinds and reasons for carrying out a blood test. Fasting rules for blood test are given in case of certain instances, that may be affected due to eating different kinds of foods. The health care professional will advice you to undergo fasting for blood test for a certain time frame. The foods we eat may affect our fasting blood sugar levels as well as lipid level. The test for low density lipoprotein (LDL), high density lipoprotein (HDL) and triglycerides may change drastically after eating. Even in our daily lives, blood and lipid levels in our body change every hour as and when eat. The rate of digestion of certain foods and drinks too affects the blood sugar and lipid levels. In order to minimize any drastic or minor changes in the basic sugar and lipid values in a blood test, one is advised a short fast.

Fasting rules in case of diabetes helps the doctor understand if a patient is truly diabetic. For example, if the blood test results for fasting are greater than 125 mg/dl, it would indicate diabetes. However, if you eat a snack bar before your test, your blood sugar level may rise above 125 mg/dl. The problem lies in the fact that, the doctor may think you are a diabetic, when actually you are not suffering from diabetes. So, for your own good, one should follow the blood test fasting rules.

The same is the case for fasting for blood work related to lipids. It is seen that the normal LDL, HDL and triglycerides values are 20 points higher when one is not in fasting state. Therefore, one could be falsely diagnosed with elevated cholesterol levels, even though the lipids are within normal range. To get a correct diagnosis of your condition and health, one needs to follow all the fasting rules for a blood test. If you even have a bite of your favorite snack, you are causing the sugar and lipid levels to elevate and give a false picture regarding the state of your health. Let us now go into the details of fasting blood test requirements.

Blood Test Fasting Rules
Our blood flows throughout our body and the blood vessels are full of cholesterol deposits. The blood sugar level too keeps fluctuating all through the day. In this case, one needs to undergo fasting so that the sugar and lipid levels come down to their actual range. This will give a correct reading and help the doctor diagnose the condition properly. Let us have a look at the fasting rules according to the type of test conducted.

Fasting Blood Test Requirements for Triglycerides Levels
It is seen that after eating, the triglycerides levels in our body can rise by 15 to 20% more than normal. Therefore, the rules for fasting before blood test for triglycerides includes a 12 hour fast. In some cases, the patient may even be asked to fast for 14 hours depending on the rate of triglycerides cells reaching the normal level.

Fasting Blood Test Requirements for Cholesterol
The time frame for fasting blood test requirements for cholesterol depends on each case, that is decided by the physician. The fasting period may range from 6 to 12 hours depending on the blood test. One may also be advised to avoid high cholesterol foods a week before taking the blood test. This helps in flushing out the extra cholesterol and brings it down to the actual level. However, one should not undergo a drastic diet change as the body will start using the available cholesterol. This will again lead to an incorrect result due to natural rise in the cholesterol levels.

Fasting Blood Test Requirements for Blood Sugar
The fasting blood sugar test or fasting blood glucose test is carried out in a similar way as cholesterol fasting. One may be asked to maintain a 12 hour fast and give the blood for testing in the night. Therefore, it is always better to avoid eating anything in the night and early morning. The body will thus, not produce any glucose from the starch present in food and give normal fasting blood sugar levels.

General Blood Test Fasting Rules
There are certain general fasting rules for blood test that one should follow for both blood sugar or cholesterol test. These rules for fasting before blood test include:
  • One should not eat anything, even a tiny bite for the entire fasting period advised by the physician, till the blood is drawn.
  • Avoid smoking, alcohol, chewing gum, etc. during the fasting period.
  • If you are on prior medications, vitamins, herbal supplements, etc. speak to your doctor about it. Some medications, vitamins, herbs, etc. may affect your blood test results. The doctor will be able to advice you whether or not you can continue or stop the medications till the blood is drawn.
  • Do not drink any liquid like tea, coffee, alcohol, juices, energy drinks, during the fasting period. You can only drink plain water to avoid dehydration when thirsty. Do not add lemon or other flavorings to your glass of water.
These are some of the rules for fasting blood test. Fasting rules for blood test need to be followed religiously as it will affect your diagnosis and treatment. If you feel weak and have a little snack during the fasting period, do not hide it. Make sure you tell the lab technician or doctor about it. They might be able to advice you if you can still go ahead with the test or plan the test some other day. This was all about the rules of fasting before blood test. If you still have some doubts, it will be wise to clear them out with your health care provider before taking the tests.
Published: August 14, 2010
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how about herbal teas ? - cathy [April 15, 2014]
After taking blood test 1 hour prior the test is it ok to eat and give medication? - aiza mae [April 16, 2013]
I live in Australia Victoria/Melbourne roxburgh park and I go to roxburgh college im also in the 10th grade find me and do me I love rapists - Jason oglesby [January 16, 2012]
great. what if you are checking for iron levels, minerals in blood? should you still fast? - sabrina [January 25, 2011]