Certain behaviors may affect some test results, such as recent or excessive exercise, not taking in enough fluids (dehydration), excessive eating, or recent sexual activity. You may be asked to refrain from some of these activities for certain tests. It should be noted that 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. If you are not given any instructions, you should ask if there are any special instructions needed to prepare for the test. 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 and interpreted correctly by your health care provider:

• Follow instructions, if there are any, to prepare for the specific test you are having performed. Alert the person collecting your sample if you have deviated from the instructions and how.
• Alert the person collecting your sample if you have deviated from the instructions and how.
• Inform your health care provider of any medications (including vitamins and supplements) you are taking. If you are taking certain prescribed medications, such as blood-thinners or seizure medication, you may want to write down the exact time at which you took your dose and when your blood was drawn. This information will be useful if your doctor has any questions about your test results.