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.
For most substances presented, the optimal levels are the ones normally found in the population as well. More specifically, optimal levels are generally close to a central tendency of the values found in the population. 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. This may also be called standard range. Reference range or reference interval usually describes the variations of a measurement or value in healthy individuals. 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.However, there are also optimal health ranges that are those that appear to have the optimal health impact on people.

Medical Tests Analyzer provides default values of reference ranges and units of measurement for each lab test procedure that produces quantitative results. However it can be specified several interval records for different ages and genders. In this same way, labs may choose to use different units of measurement for your test results. By using the tool you will be able to adjust the reference ranges and units of measurement and store them. Some lab test parameters such as Calcium (Ca), Sodium (Na), Potassium (K) and others can be measured in mmol/L (or mEq/L) or in mg/dl. He can decide to note your weight in pounds or in kilograms. Regardless of the units that the lab uses, your results will be interpreted in relation to the reference ranges supplied by the laboratory. You can adjust measurement units naming and reference ranges as well. By using the 'Reference Ranges' interface you are able to update name of measurement units and the parameter's reference range. The units of measurement along with reference ranges that labs use to report your results can vary from lab to lab. Your laboratory report may show different units of measurement than we have in Medical Tests Analyzer and the naming can be updated as well. Usually there is only one record of reference range interval for each test procedure. The units of measurement that labs use to report your results can vary from lab to lab. It is similar to the way, for instance, your physician chooses to record your weight during an examination.