reference values

a set of values of a quantity measured in the clinical laboratory that characterize a specified population in a defined state of health. The values obtained from a statistical sample are used to establish a reference interval that covers 95 per cent of the values of the healthy general population or of specific subpopulations differing in age and sex. These concepts were originally and are still widely referred to as “normal values” and the “normal range,” but the use of these terms is now discouraged because of their implication that values falling outside of the reference interval are “abnormal” or “unhealthy,” which has led to much confusion. It must be remembered that, by definition, 5 per cent of healthy individuals fall outside of the reference interval.