Wednesday, 2 March 2016

Out of range test results!! What does this mean?

The most often asked question in my years of working as a pathologist has been; “My lab tests are a little above or below the given range?"

A minimal deviation from the given reference range raises the anxiety levels of most patients. This is followed by many more questions. Is this a cause for concern? Do I have some dreadful disease?

I would like to address this issue and hope it helps someone alleviate his or her anxiety.

Reference Range for a test, also referred to in lay terms as “normal range” is an average of values for a specific test. Testing a number of healthy individuals who do not have the disease which the specific test is intended to diagnose, enables laboratories to set a reference range for that test. The range also takes into account the age, gender, location, ethnicity etc.
  • Since this is an average, there will always be people who may fall outside the range with minimum deviation.
  • If such an individual is healthy, has no signs and symptoms correlating to the minimally “out of range” values, there is no cause for concern.
  • However, be cautioned, this conclusion has to be made by a physician in context of your overall physical examination and clinical history.

If a physician orders a repeat test, it is important to have the test done from the same laboratory, provided it is an accredited laboratory with history of quality work. Why is this important?
  • Reference ranges may vary between laboratories.
  • The labs may serve different sets of population and ethnicities, may use varying test methodology or equipment leading to variations in reference ranges.
  • So for follow up of a particular test, it’s always best to stick to one specific laboratory. This allows the physician to compare the results without having to deal with all the variables. It’s like comparing apples to apples and oranges to oranges.
  • These recommendations presume that the laboratory maintains adequate quality control and quality assurance.

So next time you have a set of lab results with values minimally outside the reference range, before pushing the panic button, please remember:
  • If you fall out of range, it does not automatically indicate you have a disease.
  • Rarely there may be other causes – misidentified sample, sample not stored properly, collected in the wrong tube etc.
  • The laboratories take extreme precautions to prevent such mishaps.
  • A single test parameter is not adequate to make any diagnosis. It’s usually a panel of tests, which is diagnostic.
  • If you are tested over a period of time, as a routine check up or for chronic disorders, your individual test results are a better reference range for you, allowing your doctor to asses your disease risk or follow up.
  • All lab tests are dynamic values and will vary every time the test is performed. As long as they are within range or correlate with your medical status a physician will be able to provide a meaningful interpretation.
 Neha Dahiya MD
If you have any questions, please feel free to leave a comment and I will try to answer as soon as possible. Thank you.

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