What do fasting blood tests show

They can then tell you if you need to reschedule your test. Be honest with your doctor or lab technician if you mistakenly ate or drank. Most fasting lab results are available for your doctor in about 24 hours. However, some tests may take longer to complete. The lab will provide a report to your doctor, and your doctor will use the report to help with next steps in your diagnosis and treatment. Learn more about the lab services we offer at Bon Secours. Sign up to receive regularly scheduled updates from us packed with healthy news, tips, research, recipes, and more — right to your inbox!

When would I need a fasting lab test? If you have one or more of these symptoms, your doctor may order a fasting lab test. If I need a fasting blood test, am I allowed to eat or drink anything? That is why people are asked not to eat for 9—12 hours before the test, which helps give an accurate profile of the amounts of these fats in the blood. Research has suggested that fasting may not be necessary before all cholesterol and triglyceride tests. However, people who are having these tests should refrain from drinking alcohol for 24 hours before the test.

It is always best for individuals to check with a doctor to see whether these new guidelines apply to them. A gamma-glutamyl transferase GGT test helps diagnose liver disease. GGT is an enzyme in the liver that helps it work effectively. A person may need to avoid all eating and drinking for 8 hours before the test, as well as avoid drinking alcohol and taking some prescription medications. An iron blood test measures the levels of the mineral iron in the blood.

This test helps identify conditions that are caused by a lack of iron in the blood, such as anemia. Iron is contained in some types of food and is absorbed very quickly from food into the blood. Therefore, if a person eats food before the iron blood test, the results may show inflated levels of iron.

To ensure accurate results, a person should fast from midnight the night before the test until after the test is done. When people eat food and drink alcohol, the food and liquid get broken down in their stomach and absorbed into the bloodstream.

This can affect the levels of certain substances in the blood, such as blood glucose or cholesterol. For correct diagnosis of these conditions, it is important that a person fasts.

Eating or drinking before the test may raise the levels of a particular substance in the blood, leading to inaccurate results. Incorrect results could in turn lead to an incorrect diagnosis.

There is a range of things that individuals can do when fasting for a blood test, such as :. As well as food and drink, there are some other things to avoid when fasting for a blood test. These include:. Before a person decides to fast, they should speak with a doctor to find out whether they should fast, and if so, for how long. If the test does require fasting, following the steps above can help an individual who has been asked to fast for a blood test to do so safely.

If fasting becomes too difficult and a person breaks the fast due to extreme hunger or thirst, they should contact the doctor to reschedule the blood test appointment. People can receive the wrong diagnosis if their blood test results are inaccurate, leading to further health complications.

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. Can I continue taking medicine during a fast? What if I make a mistake and have something to eat or drink besides water during my fast? When can I eat and drink normally again? As soon as your test is over.

You may want to bring a snack with you, so you can eat right away. Is there anything else I need to know about fasting before a blood test? References Allina Health [Internet]. Atlanta: U. Boston: Harvard University; — Ask the doctor: What blood tests require fasting?