With some lab tests, it is possible for healthy individuals to receive varying results. These variations can be caused by factors such as sex, race, weight, and medical history. The same individual could even receive different test results on different days, depending on factors like stress, sleep quality, and diet.
In other words, there is often no singular “normal value.” Instead, there is a range of normal values called the “reference range;” for example, 16–30 mg/dL (milligrams per deciliter). In general, healthy individuals will have results that fall somewhere within this reference range.
Each lab test has its own reference range. When you receive your results paperwork, it should show the reference range as well as your individual results.