Reference Range Metric
What is a Reference Range?
The Reference Range (also called reference interval or normal range) is the set of values that is generally expected for a healthy population. It's used to interpret laboratory test results.
How Reference Ranges are Determined
Reference ranges are established by testing a large group of healthy people and calculating the middle 95% of results (typically the 2.5th to 97.5th percentile).
Factors Affecting Reference Ranges
- Age: Normal values change throughout life
- Sex: Some values differ between men and women
- Pregnancy: Alters many normal values
- Ethnicity: Some variations exist between populations
- Testing Method: Different laboratories may have different ranges
Interpreting Results
- Within Range: Generally considered normal
- Outside Range: May indicate a health issue, but not always
- Slightly Abnormal: May be due to natural variation or temporary factors
Related Terms
- CBC: Complete Blood Count (uses reference ranges)
- Status: Result status (High, Low, Normal)