Pin Me

Fasting Before Blood Tests for More Accurate Results

written by: Leigh A. Zaykoski•edited by: Leigh A. Zaykoski•updated: 3/9/2009

Fasting before blood tests is required if you want to get the most accurate results. Find out why fasting before blood tests is so important.

  • slide 1 of 5

    Fasting before blood tests is required for a number of different laboratory tests that are used to monitor a patient's health or diagnose and monitor a variety of health conditions such as diabetes, high cholesterol, and kidney failure. These blood tests are very important in monitoring health and detecting any abnormalities, so patients need to be sure that nothing they do will cause inaccurate results. There are several ways that the results can be altered if a patient does not comply with the doctor's order for fasting before blood tests.

  • slide 2 of 5

    Fasting for Blood Tests Measuring Glucose

    Glucose is tested in several blood panels including the basic metabolic panel and comprehensive metabolic panel. Your glucose levels rise and fall in response to many factors, one of which is how much and what kind of food you eat. Fasting for blood tests that measure your glucose level is required so that doctors can get an accurate reading. If you do not fast, your results could be inaccurate, causing unnecessary tests or treatments to determine the cause of the false results.

  • slide 3 of 5

    Fasting for Blood Tests Measuring Cholesterol

    The lipid profile tests the levels of triglycerides and cholesterol in your blood. The test measures total cholesterol as well as levels of good (HDL) and bad (LDL) cholesterol that are in your body. Fasting for blood tests that check your cholesterol levels is very important. If you eat fatty foods that are high in cholesterol, and then have this type of test performed, your results may be high. Conversely, you should not try to get a good result on the test by eating a healthy diet for several weeks before the test. Your doctor needs to get a true measure of your cholesterol levels and will not be able to identify any problems if the results are skewed due to a temporary change in your eating habits.

  • slide 4 of 5

    Fasting for Blood Tests Measuring Lactose Tolerance

    Some people who are experiencing symptoms of lactose intolerance may be instructed to undergo lactose intolerance testing. This test will find out how the body responds to increasing levels of lactose. Fasting for blood tests measuring lactose intolerance is very important because many foods could contribute to abnormal results.

    Fasting for blood tests can be difficult, especially if your test is not scheduled until the afternoon, but it's important for getting accurate results for many blood tests.

  • slide 5 of 5

    Fasting Before Blood Tests Reference Materials

    Medline Plus. National Institutes of Health. "Glucose Test - Blood." Retrieved January 31, 2009. Available: Medline Plus

    Columbia University. Go Ask Alice. "Cholesterol Screening Test." Retrieved January 31, 2009. Available: Go Ask Alice!

    Laboratory Corporation of America. "Lactose Tolerance Test." Retrieved January 31, 2009. Available: LabCorp