Which blood tests require fasting

It depends on the type of blood test you're having. The healthcare professional arranging your test will tell you if you need to do anything to prepare for it. You can eat and drink as normal before some blood tests. But if you're having a "fasting blood test", you will be told not to eat or drink anything other than water beforehand. Sometimes my doctor tells me it's okay to eat before a blood test, and sometimes it isn't.

Why is that? Actually, fasting affects the results of very few blood tests. For example, measurements of kidney, liver, and thyroid function, as well as blood counts, are not influenced by fasting. However, fasting is required before commonly ordered tests for glucose blood sugar and triglycerides part of the cholesterol, or lipid, panel for accurate results.

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Thanks for visiting. Don't miss your FREE gift. Most tests don't require fasting or other special preparations. For others, you may need to avoid certain foods, medicines, or activities. Taking the right steps before testing helps ensure your results will be accurate.

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health. Fasting for a Blood Test. Why do I need to fast before my blood test? What types of blood tests require fasting?

The most common types of tests that require fasting include: Glucose tests , which measure blood sugar. One type of glucose test is called a glucose tolerance test. For this test you will need to fast for 8 hours before test. When you arrive at the lab or health care facility, you will: Have your blood tested Drink a special liquid containing glucose Have your blood re-tested one hour later, two hours later and possibly three hours later Glucose tests are used to diagnose diabetes.

Lipid tests , which measure triglycerides , a type of fat found in the bloodstream, and cholesterol , waxy, fat-like substance found in your blood and every cell of your body. How long do I have to fast before the test? Can I drink anything besides water during a fast?

In addition, you should not : Chew gum Smoke Exercise These activities can also affect your results.