Published: 26 Mar 2023

It is a basis for a physician or other health professional to interpret a set of results for a particular patient.
Reference ranges are usually given as what are the usual (or normal) values found in the population, more specifically the prediction interval that 95% of the population fall into. In contrast, optimal (health) range or therapeutic target is a reference range or limit that is based on concentrations or levels that are associated with optimal health or minimal risk of related complications and diseases. However, there are also optimal health ranges that are those that appear to have the optimal health impact on people. The standard definition of a reference range (usually referred to if not otherwise specified) basically originates in what is most prevalent in a reference group taken from the population. However, usual and optimal levels may differ substantially, most notably among vitamins and blood lipids, so these tables give limits on both standard and optimal (or target) ranges.This may also be called standard range. More specifically, optimal levels are generally close to a central tendency of the values found in the population. For most substances presented, the optimal levels are the ones normally found in the population as well. Reference range or reference interval usually describes the variations of a measurement or value in healthy individuals.

You must use the range supplied by the laboratory that performed your test to evaluate whether your results are 'within normal limits'.Most people can now access their lab test results directly via the Internet, but very few lab reports have been designed to convey the meaning of those results in a way people who are not health professionals can understand or put in context. This may be due to differences in lab testing equipment, chemical reagents, and analysis techniques. The information provided in this article will help you understand:
Why so few reference ranges are provided in the test information on this site: the accuracy of laboratory testing has significantly evolved over the past few decades, but some lab-to-lab variability can occur.