Abnormality of metabolism/homeostasis Abnormality of vitamin metabolism 2010-12-17T06:17:22Z UMLS:C4022036 An anomaly in the metabolism of a vitamin. Vitamins are organic substances that are essential in minute quantities and not produced within the body, instead being present in natural foodstuffs. Vitamins act as coenzymes or precursors of coenzymes in the regulation of metabolic processes. Abnormality of vitamin metabolism HP:0100508