When Fasting for Blood Work is Required

November 12, 2012

When Fasting for Blood Work is Required

Blood work or testing often requires that the patient fasts for a period of time before testing. Many everyday blood tests, such as for cholesterol and triglyceride levels require fasting. Fasting for blood work to be carried out can be confusing as different blood tests have a different baseline of fasting.

Fasting prior to a blood test is very important and it is dependent on what you are being tested for. Blood tests for diabetes or triglycerides require fasting prior to any blood work being carried out. Fasting for blood work testing for triglyceride levels requires fasting for 12 hours prior to the blood test, and in some cases it may be 14 hours. Water is allowed during the period of fasting but coffee has to be avoided. To ensure accurate measurements of the triglycerides within the blood it is essential to fast overnight and the blood test will be carried out in the following morning. It is important to have only water as anything else may raise the levels of triglycerides in the blood. If you have eaten food the triglycerides levels may appear higher in the blood and the doctor will have to give you prescription medicine. Alcohol and vitamin supplements should be avoided for 24 hours minimum prior to the blood test. Inform your doctor if you are using cortisones, antibiotics or any antihistamines.

Your doctor will inform you of the precise period of fasting prior to any blood testing being carried out, and this time ranges between 9 and 12 hours prior to the blood being taken. A requirement prior to having a blood test to check for cholesterol levels is to keep a record of the food you have been eating for the week before the test. Avoid eggs, red meat and any other food which contain high cholesterol levels in them. This is a very important requirement if the blood test is being carried out for insurance purposes. Do not make any radical changes in your diet prior to this test as this may lead to an inaccurate diagnosis and the treatment received may not be suitable. If the blood shows high cholesterol levels in it and you have carried out the fasting for blood work then it means that you may be at a higher risk of heart attacks, blockages and heart disease.

Fasting may not be required if the test is being carried out on complete cholesterol readings and HDL cholesterol. Should these tests be carried out and no fasting has been done, the LDL cholesterol levels will be inaccurate.

Fasting before measuring blood sugar levels requires not eating for 12 hours. Making a morning appointment for the test means it is easier as you will be overnight fasting. Ensure that you do not eat 12 hours before the test, even a piece of gum with sugar or sweetener will affect the outcome of the glucose levels in the blood.

Fasting for blood work is a requirement when being tested for vitamin E and/or vitamin A levels. Again 12 hours of fasting is essential before the blood tests are carried out and any supplements which are being taken should be stopped 24 hours before the test. An 8 hour fasting period can be carried out but this is based on the recommendation of the doctor who has requested the test.

Drinking water may be permitted when fasting for blood work but always consult with your doctor in the first instance to get the correct answer.

If for any reason you have not been able to fast for the hours instructed it is important to inform the laboratory that in fact you have eaten or had something to drink prior to the blood test and a decision can be taken to either reschedule or go ahead with the appointment.

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