1. Health

Understanding Your Medical Test Results

Positives, Negatives, Relative Values - What Do They Mean?

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Updated April 30, 2014

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Be sure you understand your medical test results and ask for clarification if you don't understand those results

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Heart and lung tests will likely provide relative results. Be sure you understand which "direction" will be an improvement.

Getty Images - Tullio M. Puglia

There are thousands of medical tests used on patients to diagnose, measure progression of a disease or condition, or measure the effectiveness of a treatment. But they all have some basic truths about what they mean to you, and how they are best interpreted.

There are two basic kinds of medical test results:

1. Tests that give yes or no answers (usually used for diagnostic purposes)

2. Tests that give relative results, as in measuring something to be higher or lower, bigger or smaller than before, or inside or outside a "normal" range.

Most medical tests deliver both kinds of results. A medical test result that is inside or outside the normal range might result in a yes or no answer.

Here is more information about these two kinds of results, and the kinds of questions you'll need answered to better understand your own health situation.

• Yes and No Tests - How They Work, and Questions to Ask

When you are given a medical test that yields a yes or no result, you will need to be sure you are clear on that yes or no, and you'll want to know how trustworthy the test is.

Yes and no tests are usually diagnostic tests - yes, your body shows signs of X disease or condition, or no, your body doesn't show those signs. A warning: the way we patients perceive yesses and nos might be the opposite of what they really mean.

For example - if the doctor says a test result is positive, then you might think that's good - when in fact, it might not be. Or when the result is negative, you might think that it's bad news when, in fact, it could be very good news.

"Positive" in a medical test sense means that whatever the test was looking for - it was found. If the test was looking for a specific type of tumor, or bad cell, or infection - then positive means yes, that tumor, cell or infection was found. In that case a positive finding may be a bad thing. Or, sometimes finding that tumor, cell or infection can be construed as good - because now you have an answer for your symptoms.

"Negative" in a medical test sense means that whatever the test was looking for was NOT found. When something isn't found, it can be a good thing (because it may mean you don't have whatever a feared diagnosis was). But it can also be a bad thing, when it means that one more potential diagnosis is being dismissed, and you still can't get a diagnosis.

Example: You are given a test for HIV, and it comes back negative. As a patient who hears that term negative, you may think that - oh no! You have HIV! (Because it would be a negative thing to be diagnosed with HIV.) But, in fact, a negative test result means that no - you don't have HIV - a good thing.

The flip side of that is true, too. If your HIV test is positive, then it means you DO have HIV. It doesn't mean that it's a good, positive result.

Once you understand your medical test results, it will be important to understand whether or not they are accurate, and whether you need to be concerned with running that test again, regardless of whether or not you are happy with the results. Learn more about understanding medical test accuracy.

• Relative Value Tests - How They Work, and Questions to Ask

Once you have been diagnosed, further testing for that diagnosed problem will usually yield relative results that are important to you. When you are given a medical test that yields relative results, usually in the form of a number, you will want to know what those results mean, and how they compare to previous results from the same test if a previous one was given - in effect, what the importance of those results are to your health, and how that might change the treatment (or lack of treatment) you've participated in to that point.

Example: People with diabetes are given an A1C test, usually three or four times per year. If you have diabetes and are given an A1C test, and your result is 7%, you need to know whether that is a good or bad test result (value) for you. The answer will differ from diabetes patient to diabetes patient. For someone who has had diabetes for a long time and previously had a result of 8%, then 7% is quite good. But for someone who previously had an A1C of 6.1%, then a 7% may indicate a problem. There is no exact answer for everyone. The results are relative to previous tests.

Questions to ask about all relative tests:

  • What is normal, and are my results normal?
  • If my results are not normal, are better results higher, or lower, bigger or smaller than the results of my test?
  • What do you recommend I do to bring them into the normal range?
  • How accurate is this test? (Learn more about medical test accuracy, for both good and bad results.)

Those are good questions for your doctor. Ask for copies of your test results, of course. You might ask for written documentation about where your doctor thinks those relative values should be for you. You might even consider tracking them over time as a way to manage your health.

And a reminder: if your test results are not what you expect, you may want to ask to be tested again. There are many ways mistakes can be made (including yes and no results).

Confirmation of any result will give you more information before you make medical decisions, and will give you confidence in any decisions you make based on those results. If the results can't be confirmed, then you'll know it's time to talk to your doctor about shifting directions.

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