Published: 30 Jul 2024

Revised and Reformatted Text:

Reference Ranges

Reference ranges are sets of values that define the expected limits for laboratory test results based on data from a group of healthy individuals. These ranges provide benchmarks for healthcare providers to assess patients' test results and determine their health status.

Components of Reference Ranges

Reference ranges include both upper and lower limits. They can vary depending on factors such as:

* Age
* Sex
* Specimen type (e.g., blood, urine)
* Circumstantial factors (e.g., fasting, exercise)

Statistical Basis of Reference Ranges

Reference ranges are derived mathematically. They represent the average value for a group plus or minus two standard deviations (95% of the population).

Interpretation of Test Results

Test results that fall outside the reference range do not necessarily indicate a health condition. Healthcare providers consider results in the context of the patient's:

* Medical history
* Current medications
* Physical examination findings
* Other laboratory and non-laboratory test results

Terminology

The term "reference range" is preferred over "normal range" as it better reflects the statistical basis of these values.

Population Variability

Reference ranges can vary across different populations. What is considered normal in one group may not be normal in another.