Why can reference ranges vary?

Reference ranges, also known as expected values, are the ranges that are considered acceptable for the specified population. For many of our health tests, different kinds of equipment and different kinds of testing methods are available. This means that each laboratory must determine which reference range is the most accurate to use for their testing method and population. DNA Tests Direct uses reference ranges available from the manufacturers of the tests that we offer and also from large studies published in peer-reviewed journals and other scientific resources. We do not recommend changing between different laboratories for serial testing.