A reference range is a set of values that includes upper and lower limits of a lab test based on a group of otherwise healthy people.
These intervals are thought of as 'normal ranges or limits.'
Though the term 'reference interval' is usually the term preferred by laboratory and other health professionals, the more commonly-known term is 'reference range,' so that is the term used throughout this article.
Reference ranges provide the values to which your health care provider compares your test results to and determines your current health status. The values in between those limits may depend on such factors as age, sex, and specimen type (blood, urine, spinal fluid, etc.) and can also be influenced by circumstantial situations such as fasting and exercise. However, the true meaning of a test result-whether it indicates that you are sick or well or at risk for a health condition-can only be known when all the other information your provider has gathered about your health, including the results of a physical exam, your health and family history, recent changes in your health, any medications you are taking, and other non-laboratory testing.
An example is glucose testing for diabetes.
Each laboratory establishes or 'validates' its own reference ranges, thus reflects differences that vary from lab to lab. In the context of your personal information, you and your provider can use reference ranges as a guide to what your results mean and to help make decisions about managing your health.The specific reference ranges that appear on your laboratory report are determined and provided by the laboratory that performed your test.
Reference ranges help describe what is typical for a particular group of people based on age, sex, and other characteristics. Through many years of research involving large, diverse populations, these limits have become standardized. A few tests do not have ranges, but limits at which decisions are made about whether you are healthy or should be treated.