Organic acids are water-soluble compounds containing one or more carboxyl groups as well as other functional groups (-keto, -hydroxy), which are intermediate metabolites of all major groups of organic cellular components:  amino acids, lipids, carbohydrates, nucleic acids, and steroids. Organic acidurias are a biochemically heterozygous group of inborn errors of metabolism biochemically characterized by the accumulation of metabolites that are either not present under normal physiological conditions, (and that accumulate as a result of the activation of alternative pathways in response to the loss of function of a specific gene product), or pathological amounts of normal metabolites. Examples of disorders identified by this test include methylmalonic acidemia, propionic acidemia, isovaleric acidemia, glutaric acidemia types I and II, Canavan disease and many others. Patients with certain fatty acid oxidation disorders and amino acid disorders also have organic acid abnormalities in urine.