Reference range
Also called Reference interval, normal range, normal values
A reference range, also called a reference interval or "normal values," is the span of results a laboratory prints beside a test result to show where most healthy people fall. It is built from the results of a large group of healthy people, and a test can have separate ranges for different groups, such as by age or sex.
A reference range describes a population, not a target for one person. A result just outside it is not always a sign of disease, and a result inside it is not a guarantee of health. Because laboratories use different methods and units, each sets its own range, so a result should be compared with the range on its own report, and trends are easiest to follow when the same laboratory is used over time.
Why it matters after 45
Ranges are usually drawn from adult reference groups, and accurate ranges for older adults are rarely available, partly because older people with no medical condition and no medication are hard to find. That is one reason a midlife result can sit "in range" while symptoms say otherwise, and why clinicians read a result against symptoms, history and earlier results. Whether an "optimal" range does better is a separate argument.
Where it comes up
Related terms
References
- MedlinePlus. How to Understand Your Lab Results. U.S. National Library of Medicine. https://medlineplus.gov/lab-tests/how-to-understand-your-lab-results/
- Risch M, et al. SENIORLAB: a prospective observational study investigating laboratory parameters and their reference intervals in the elderly. Medicine (Baltimore), 2017. https://pmc.ncbi.nlm.nih.gov/articles/PMC5228672/
Definitions here are educational and are not medical advice. They explain what a term means; the pages linked above cover what it means for you, and a clinician reviews your own results. Editorial & medical review policy · All glossary terms