Labs
How do I prepare for a blood test?
Written by the Forever Young IV Bar teamPublished
Some blood tests need fasting and many do not. If you are told to fast, that usually means nothing but plain water for 8 to 12 hours. Tell your provider about every medicine, vitamin and supplement you take, and follow their exact instructions. Your provider decides which tests are right for you.
Do I need to fast?
It depends on the test. MedlinePlus says that for many lab tests you do not need to do anything except answer questions, but some need preparation. One of the most common is fasting, which means no food or drink except water for up to several hours or overnight.
MedlinePlus explains that nutrients from food are absorbed into your bloodstream and can change the results of certain blood tests. Fasting can help improve the accuracy of your test results. Tests that often need fasting include blood glucose and cholesterol and triglyceride tests, but your provider tells you for your test.
- You usually need to fast for 8 to 12 hours, and your provider gives the exact time.
- Plain water is allowed. Juice, coffee, soda and flavored sparkling water are not.
- Do not chew gum, smoke or exercise during the fast.
- If you eat or drink by mistake, tell your provider. You may need to reschedule.
- Fasting tests are often booked early in the morning, so most of the fast happens while you sleep.
What else can change your results
MedlinePlus lists several common things that can affect results:
- certain foods and drinks
- certain medicines or supplements
- hard exercise before your test
- having a menstrual period at the time of your test
- not following the preparation instructions
What to bring and tell your provider
Tell your provider about all the medicines, vitamins and supplements you take. MedlinePlus advises that you do not stop any medicine unless your provider tells you to. MedlinePlus also notes that some blood tests ask you to drink extra water to help keep more fluid in your veins, so ask whether that applies to yours.
If your fasting test is ordered by a provider, you will usually get written instructions. MedlinePlus advises asking questions at least a full day before the test so you have time to prepare.
After the draw
You can eat as soon as the test is over. MedlinePlus says it is common to feel light-headed after a blood test that requires fasting, so bring a snack.
A lab result is one piece of the picture. MedlinePlus says your provider uses your results along with your exam, health history and family history, and that it is important to talk with your provider about what your results mean for you.
Book a visit or ask a question
Our team can tell you which of our lab services need preparation. You can book online at foreveryoungivbar.com/book/ or call 469-613-7033. Our Plano studio is at 2609 Technology Drive, Suite 108 (inside Habitat Commons). A nurse can also come to you for mobile visits across Dallas-Fort Worth, which are booked by phone.