You play an important role in ensuring you get most benefit from your tests and that your test results are accurate. It is important you do everything you can to make sure the information you provide is correct and that you follow instructions closely.
Effective communications between you and your healthcare team is essential. The choice of tests your doctor makes will be based on your clinical history and symptoms. Tell them everything you think may have a bearing on your healthcare. You may feel uncomfortable or embarrassed talking about some aspects of your health in the consulting room – but your diagnosis depends on you being honest and open with them.
Give them your complete personal, medical and family history and tell them about any medications that you are taking at the time of testing, including herbal remedies and supplements, as these can affect the results. You also may be asked about the amount of alcohol you drink and if you smoke. Providing complete, accurate information is essential to the reliability of your test results.
Find out why tests need to be done, how they will be done, and what your doctor expects to learn from them. Make some notes to take along if this helps. Ask:
Your doctor is the best person to answer these questions. Take notes of what they say, if this helps. If you forget anything that you’ve been told you may find the answers on this website.
Children, people who have a disability and the elderly may need special help when having a sample taken. Please see Coping with discomfort and anxiety.
Pathology tests are only as good as the samples on which they are performed. Most tests are straightforward and require no preparation but others require you to make some changes. Some tests require you to fast, to stop eating certain foods or to stop taking medications or supplements. Some require you to give a sample at a specific time.
Be sure to check with your doctor or their medical practice about their instructions rather than relying on the information on this or other web sites, as procedures can differ between testing laboratories.
If you have any doubts about whether you have prepared properly, check with the person taking your sample – the nurse or the collector at the laboratory’s collection centre (phlebotomist). For a brief outline on the way samples are collected see How samples are collected.
Some tests such as blood lipids (cholesterol and triglycerides) and glucose require you to fast before you give the sample because food can affect the results. In the first few hours after you eat, many chemicals in your blood undergo changes.
Changes can also occur if you don’t eat for an extended period. So, fasting for too long can also affect the results. In most situations, fasting means not eating for between three and 12 hours. Samples for fasting blood tests are often collected in the morning after an overnight fast. For most fasting tests you are advised to drink water as normal. Being dehydrated can also affect results. However, some tests require you to stop drinking water.
The types of food you eat can be important when preparing for some tests. Some tests require you to avoid certain food, others require you to eat a low or high fibre diet.
Smoking and alcohol
Some tests require you to stop smoking or stop drinking alcohol.
Medications and/or supplements
Some tests require you to stop taking medications and/or supplements. This must be done under your doctor’s supervision. For example, allergy testing means stopping antihistamines; the Hydrogen Breath Test requires you to stop taking antibiotics and laxatives; and if you are having a test for H. pylori you must stop taking antibiotics, bismuth medication and proton pump inhibitors.