A reference value indicates the accepted normal range for a specific laboratory test. When your results are ready, they are compared against these reference values to determine whether the outcome is within the normal range or shows any deviation.
Different diagnostic laboratories use a wide variety of analyzers to process test results. For example, biochemistry and immunochemistry tests can be processed using many different devices, each potentially produced by different manufacturers. In addition, the testing methodologies may vary between laboratories.
All these factors — the type of analyzer, the manufacturer of reagents, and the specific method of testing — can affect the reference range. Therefore, each laboratory provides its own reference interval on the test result form. While these reference values are based on internationally accepted standards, they also reflect the specific features of that laboratory, including the technical specifications of the equipment used, the method of testing, the measurement units, and more.
As a result, the reference range for the same test may differ significantly from one laboratory to another, and there is no such thing as a “universal reference range.”
When interpreting lab test results, the treating physician must always consider the reference intervals stated on the test report from the specific laboratory.
To ensure accurate interpretation, effective monitoring, and reliable follow-up tests, it is strongly recommended to perform repeat tests using the same method and in the same laboratory whenever possible.