What does it mean when my doctor orders a laboratory test? A lab test is a medical procedure performed on a sample from your body, usually blood or urine. The tests may be done by your doctor or by a laboratory technician.

If you have symptoms of an illness or disease, your lab test results can help your doctor confirm or diagnose your condition. Your doctor may also use the tests to help plan your treatment, evaluate your response to it, and to monitor your health over time.

"Screening" tests (often part of your routine health check-up) are used to look for significant changes in your health before any symptoms are noticed.

What is a "normal" result? In the laboratory, your doctor or a technician will take your test sample and analyze it. If you're healthy or your disease is under control, you'll probably have a normal reading. Because there's a lot of natural variation between one person and another, there are usually a wide range of results that can be considered normal. Results that are normal for you may not be normal for another person, and vice versa. (It's also fairly common for the normal range of values to be defined slightly differently from one lab to another.)

Test results can be affected by a range of different factors, including your age, gender, ethnicity, medical history, present state of health, and even the food or medicine you've just taken. That's why your doctor may ask you to avoid eating or drinking for several hours before a test, for example, or not to take medications. Before taking a test, it's good to ask your doctor how you should prepare for it.

How will my tests be used? All laboratory tests should be viewed and interpreted in the context of your general health picture. Your doctor will usually consider your test results together with those from other tests and procedures. Some laboratory tests, such as those for sexually transmitted diseases, can clearly pinpoint specific health problems. Other results help provide a general health picture and aid your doctor in identifying possible problems. The information your doctor collects from your laboratory test results may help him or her to diagnose your condition, or to plan or revise your recommended treatment.

Give your doctor all the information you can about your medical history and present condition. If you have questions or concerns about your test results, ask your doctor to discuss these with you.

What questions should I ask my doctor about lab tests?

•What kinds of tests will I have, and what are they called?

•How much will they cost? Are they covered by my health insurance?

•I don't have health insurance. Are any of these tests available for free or at low cost at a public health clinic?

•What do you expect to find out from these tests?

•How long will it take for results to come in? When will you contact me about them?

•When should I call if I don't hear from you?

•Do I have to do anything special to prepare for any of the tests?

•Do these tests have any side effects or risks?

•Will I need more tests later on?

For your treatment to be most successful, it's essential to understand your doctor's responses to your questions. Here are some important tips for doing this:

•If you don't understand your doctor's responses, keep asking questions until you do.

•Take notes, or get a friend or family member to take notes for you. You might even want to bring a tape recorder to assist in your recollection of the discussion.

•Ask your doctor for a written copy of his or her instructions.

•Ask your doctor for printed material about your condition.

•If you still have trouble understanding your doctor's answers, ask where you can go for more information.

Other members of your health care team, such as nurses and pharmacists, can be good sources of information. Talk to them, too.

-- Diana Reiss-Koncar is a freelance writer living in Oakland, California.

References

First published June 23, 2004
Last updated February 26, 2008
Copyright © 2004 Consumer Health Interactive