Reference ranges for blood tests

Reference ranges (reference intervals) for blood tests are sets of values used by a health professional to interpret a set of medical test results from blood samples. Reference ranges for blood tests are studied within the field of clinical chemistry (also known as "clinical biochemistry", "chemical pathology" or "pure blood chemistry"), the area of pathology that is generally concerned with analysis of bodily fluids. Blood test results should always be interpreted using the reference range provided by the laboratory that performed the test. A reference range is usually defined as the set of values 95 percent of the normal population falls within (that is, 95% prediction interval). It is determined by collecting data from vast numbers of laboratory tests. In this article, all values (except the ones listed below) denote blood plasma concentration, which is approximately 60–100% larger than the actual blood concentration if the amount inside red blood cells (RBCs) is negligible. The precise factor depends on hematocrit as well as amount inside RBCs. Exceptions are mainly those values that denote total blood concentration, and in this article they are: All values in Hematology – red blood cells (except hemoglobin in plasma) All values in Hematology – white blood cells Platelet count (Plt) A few values are for inside red blood cells only: Vitamin B9 (folic acid/folate) in red blood cells Mean corpuscular hemoglobin concentration (MCHC) Mass concentration (g/dL or g/L) is the most common measurement unit in the United States. Is usually given with dL (decilitres) as the denominator in the United States, and usually with L (litres) in, for example, Sweden. 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. International units (IU) are based on measured biological activity or effect, or for some substances, a specified equivalent mass. Enzyme activity (kat) is commonly used for e.g.