Published: 3 Sep 2024

Reference Populations and Ranges

Defining the Reference Population

To determine reference ranges for laboratory tests, a specific group of individuals, known as the reference population, is defined. This population is carefully selected based on relevant characteristics such as age, sex, race, general health status, and medical history.

Selecting a Reference Population

Depending on the specific test and factors that may affect its results, reference populations may be established based on one or more of the following criteria:

* Age
* Sex
* Race
* General health
* Medical history

Establishing Reference Ranges

Once the reference population is defined, a large number of individuals (typically at least 120) are tested under standardized conditions. The results are statistically analyzed, with reference ranges typically encompassing the values that fall within the middle 95% of the reference population.

Laboratories may establish reference ranges through various methods:

* Conducting their own studies
* Adopting ranges provided by test manufacturers or other labs
* Deriving ranges from existing patient data

Importance of Reference Populations

The reference population is crucial in determining accurate reference ranges because it represents the specific group of individuals that the results will apply to.

Terminology

The term "reference range" is preferred over "normal range" as it acknowledges that values within a range may vary among different populations.

Individual Considerations

When interpreting test results, it is important to consider whether the result falls within the laboratory's reference range. However, the result should also be evaluated in the context of the individual's personal circumstances, including medical history, current medications, and other relevant information.