One of the most important factors in determining the accuracy and reliability of your lab test is you, the patient. After all, it is a sample from your body – blood, urine, or some other specimen – on which the test will be performed.  Therefore, it is essential that you do the following to ensure that the results will be useful:

1. Follow instructions, if there are any, to prepare for the specific test you are having performed;
2. Alert the person collecting your sample if you have deviated from the instructions and how;
3. Inform your doctor of any medications (including herbal remedies) you might currently be taking or foods you have eaten within the day prior to the test.

Many tests require no special preparation, but for those that do, be certain to adhere to the instructions provided. If you are ever unclear about the instructions, be sure to ask the person ordering the test for clarification.

Some of the more common types of preparation required for testing include fasting (to go without all or certain foods) for several hours before the test or even overnight. Certain tests may require you to increase or decrease the amount you drink for 10 to12 hours ahead of the test. There may be specific foods and medications you will need to avoid or you may even may be asked not to smoke before the test.

Examples of some frequent laboratory tests that require advance preparation include:

• Glucose tolerance, samples taken when fasting or two 2 hours after food for blood glucose tests – fasting or eating meals at specific times may be required 
• Faecal occult blood test – certain food and/or medication restrictions required
• Serum lipids (triglycerides, cholesterol, etc.) – overnight fasting may be required

On Lab Tests Online, we provide general information about test preparations you may need to follow before taking certain tests. This information is usually included in the “Is there anything else I should know?” section under “The Test” tab in our test descriptions. However, please be sure to check with your doctor for their instructions rather than relying on the information on this or other web sites, as different labs may have varying testing protocols.

Finally, with laboratory testing, like other aspects of medical care, it is crucial that you are open and honest with your health care provider. Just as you should give them your complete personal, medical, and family history, you may need to report any medications that you are taking at the time of testing, including herbal remedies, as these can affect the results. You also may be asked about the amount of alcohol you consume or tobacco products you smoke. Providing complete, accurate information will help to ensure the reliability of your test results.

Sources and Links:

South Bend Medical Foundation, Inc.: Patient Information: Pre-Test Requirements - another good example

Consumer Laboratory Testing Information Page