Clinical Decision Support System

To determine ranges, labs may conduct their own studies for the tests they perform, they may adopt reference ranges from test manufacturers or other labs, or they may derive reference ranges from existing patient data.

The most important step in determining a reference range for any test is to define the reference population - the group of people who will be represented in the reference range. Depending on the test and factors that may influence its results, reference populations may be chosen based on age, sex, race, general health, and/or medical history.
Next, a large number (minimum of 120) of people who fit the profile of the reference population are tested under nearly identical conditions, and the results are analyzed.
For many tests, reference ranges include the values that are statistically analyzed and reported for the middle 95% of the reference population.

Reference ranges for blood tests are sets of values used by a health professional to interpret a set of medical test results from blood samples. Is usually given with dL (decilitres) as the denominator in the United States, and usually with L (litres) in, for example, Sweden. International units (IU) are based on measured biological activity or effect, or for some substances, a specified equivalent mass. Molar concentration (mol/L) is used to a higher degree in most of the rest of the world, including the United Kingdom and other parts of Europe and Australia and New Zealand. Mass concentration (g/dL or g/L) is the most common measurement unit in the United States. liver function tests like AST, ALT, LD and v-GT in Sweden.Reference ranges for blood tests are studied within the field of clinical chemistry, the area of pathology that is generally concerned with analysis of bodily fluids. Enzyme activity (kat) is commonly used for e.g.