Preparing for your Lab test
WHAT TO EATCertain tests require a fasting specimen. Be sure to check with your doctor to see if you need to fast for your tests. For tests requiring fasting, your doctor may recommend that you fast for 8-12 hours prior to the test. Fasting patients should not eat anything during the fast period but are encouraged to stay hydrated during this period by drinking an adequate amount of water. However, no other beverages, including black coffee, tea or juice should be consumed. Chewing gum, smoking and excessive exercise should also be avoided during the fast period, as these activities can affect your cholesterol, blood sugar and insulin levels, even if gum or beverages are sugar-free.
Some tests may require that you avoid certain foods before or while you collect your sample.
WHAT TO DRINK
Regardless of whether or not your are fasting, you need to drink plenty of water before you have your blood drawn. Dehydration affects not only your overall well-being but your test results and how easily your blood can be drawn.
MEDICATIONS AND VITAMINS
Make sure your doctor knows all of your current medications and supplements. Some of these can influence the results of your lab tests. For example, St. Johnís Wort can reduce Digoxin levels and CoQ10, Ginkgo biloba and Fish Oil can interfere with the function of Coumadin. Check with your doctor about which medications and supplements you should take the day of your test.
ON THE DAY
Be sure to inform the laboratory staff if you deviated from the preparation instructions, for example if you had a meal before a fasting test. If your specimen is being collected at the lab, be sure to bring your doctorís order, insurance card and identification.