Metabolic diseases or disorders interrupt the normal processes of metabolism within the body, the many chemical reactions responsible for breaking down food and either using, storing, or disposing of the energy it contains. When something goes wrong with any of these processes due to lack of or excess production of an enzyme or hormone, a metabolic disease results. This leads to a substance building up in dangerous quantities, or to various deficiencies.
Many different types of metabolic disease affect chemical processes within the body, and researchers discover more all the time. The severity of symptoms depends on which metabolic disease a person has. Some conditions, such as Tay-Sachs disease, prevent the body from producing the enzymes that break down particular substances within the body. As a result, the substances build up to harmful quantities. Metal metabolism disorders, such as Wilson's disease, prevent the body from breaking down particular metals.