Determining Reference Ranges

Laboratories may establish their own reference ranges through studies, adopt guidelines provided by test manufacturers or other labs, or utilize patient data to derive ranges.

Establishing Reference Populations

The key step in defining reference ranges is establishing the reference population, which represents the individuals included in the range. Factors such as age, sex, race, health status, and medical history may guide the selection of reference populations.

Data Collection and Analysis

A significant number of individuals (minimum 120) fitting the reference population are tested under standardized conditions. The resulting data is then analyzed.

Defining Reference Ranges

For numerous tests, reference ranges encompass the values that fall within the middle 95% of the reference population.

Specific Reference Ranges

Uric Acid: Normal range varies with age and sex. For example, in adults, the normal range is 3.5-7.2 mg/dL.

White Blood Cell Count: Normal range for adults: 4,500-11,000 cells/mcL.

Blood Test Interpretation

Blood test results are crucial in assessing overall health. They provide valuable information about physical well-being at the time of testing. Interpretation should be performed by healthcare professionals familiar with individual medical history.

Normal Ranges and Variations

Test results are compared against "normal ranges" established for specific population groups and individuals. However, variations beyond these ranges can have various causes.