how long should you fast for routine blood work?
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It is important that a person has not had anything to eat or drink other than water for 8 to 10 hours before a fasting blood glucose test. Fasting helps ensure that the blood test records an accurate measure of fasting blood sugar levels. The results help a doctor to diagnose or rule out diabetes.
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Fast for 12 hours a day A person needs to decide on and adhere to a 12-hour fasting window every day. According to some researchers, fasting for 10–16 hours can cause the body to turn its fat stores into energy, which releases ketones into the bloodstream. This should encourage weight loss.
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You will usually need to fast (not have any food and only drink water) for between 9 and 12 hours before having this test. Most people have the test in the morning so it doesn't interfere with their day and their meals.
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Tell your doctor about any prescription or over-the-counter medications or supplements you're taking. You may need to fast (refrain from eating or drinking) for four hours before the test.
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Other blood tests that require fasting Basic or comprehensive metabolic tests: Tests for blood sugar, electrolyte balance, and kidney function. Typically, people will be asked to fast for 10 to 12 hours before having one of these tests.
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You should fast for 8 hours before having an iron level blood test. This is to ensure that levels of iron detected in your blood are not skewed by food or drink intake. If you're having a blood test for ferritin levels – a measure of how much iron is stored in the body – you don't usually need to fast before.
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You usually need to fast for 8–12 hours before a test. Most tests that require fasting are scheduled for early in the morning. That way, most of your fasting time will be overnight.
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For these blood glucose tests used to diagnose diabetes, you must fast at least 8 hours before you have your blood drawn.
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Fasting before a blood test is when people are asked not to eat or drink anything other than water before some blood tests. But which blood tests require fasting and how can people fast safely? Fasting is not always necessary before a blood test, but when it is, it is only for a short time.
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Popular forms of intermittent fasting Keep in mind that for the purpose of these discussions we will consider the baseline standard diet to involve 12 hours of fasting (overnight) plus 12 hours of an eating window during the day consisting of three meals, breakfast, lunch, and dinner.
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The amount of time you need to fast for will vary depending on the test. For most tests, you will be told not to consume anything but water for eight hours leading up to the test.
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a fasting blood glucose test (used to test for diabetes) – you fast for 8 to 10 hours before the test. an iron blood test (used to diagnose conditions such as iron deficiency anaemia) – you fast for 12 hours before the test.
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Should the patient fast before the appointment? For a physical, my staff advises patients to fast eight hours prior to the appointment for the bloodwork. Water and a cup of black coffee is fine if you usually drink it in the morning, though.
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You usually need to fast for 8–12 hours before a test.
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Your results could come back wrong if you give in to temptation. Fasting means you don't eat or drink anything but water usually for 8 to 12 hours beforehand. So, if your appointment is at 8 a.m. and you're told to fast for 8 hours, only water is okay after midnight.
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You may be instructed not to eat or drink anything except water for 9 to 12 hours before having your blood drawn. This is called a "fasting blood test." Fasting is not always necessary, but it may be recommended. Usually, you are allowed to take your medicines with water the morning of the test.
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an iron blood test (used to diagnose conditions such as iron deficiency anaemia) – you fast for 12 hours before the test.