One of the most important factors in making sure your laboratory test is accurate and reliable 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. It is therefore, important that you take the following steps to ensure that the results will be useful and correctly interpreted by your doctor or laboratory:
1. Follow any instructions you have been given to prepare for the specific test you are having performed;
2. Tell the person who collects your sample if you have not followed the instructions;
3. Inform your doctor of any medicines (including vitamins, supplements and herbal remedies) you might be taking now or have done so recently;
4. Inform your doctor of foods you have eaten within the day prior to the test;
5. If you are taking prescribed medicines, such as anticoagulants (blood-thinning drugs) or anticonvulsants (seizure medication), it is helpful to write down the last time you took your dose. This information may help the doctor if he or she has any questions about your test results.
Many tests require no special preparation, but for those that do, it is important to adhere to the instructions provided. If you are ever unclear about the instructions, be sure to ask for clarification from the person who requested the test. If you are not given any instructions, you should ask if there is anything you need to do to prepare for the test. For more complicated test procedures, a sheet of written instructions may be available.
Some of the more common types of preparation required for testing include fasting (to go without food) for several hours before the test or even overnight. Certain tests may require you to increase or decrease the amount you drink for 10 to 12 hours before the test. There may be specific foods and medicines you will need to avoid. You may be asked not to smoke or take alcohol or to limit exercise or abstain from sexual activity before the test.
Examples of some common laboratory tests that require advance preparation include:
- Glucose tests or glucose tolerance tests: - fasting for 12 or more hours 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
- PSA test - abstinence from sexual activity for 24h before the test may be required
On Lab Tests Online, we provide general information about instructions you may need to follow before certain tests. This information is usually included on the ‘Test sample’ page of our test descriptions if any preparation is needed. However, please be sure to check with your doctor for his or her instructions rather than relying on the information on this or any other web site, as different laboratories and doctors may have alternative testing procedures.
Finally, with laboratory testing, like other aspects of medical care, it is important that you are open and honest with your doctor or nurse. Just as you should give them your complete personal, medical, and family history, you may need to report any medicines that you are taking at the time of testing, including herbal remedies, vitamins or supplements, 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.