Acute Metabolic Decompensation in an Adult Patient With Isovaleric Acidemia

Jeffrey A. Feinstein, MD, Kevin O'Brien, MD


South Med J. 2003;96(5) 

In This Article

Abstract and Introduction

Isovaleric acidemia is a rare autosomal recessive inborn error of leucine catabolism caused by deficiency of isovaleryl coenzyme A dehydrogenase. This enzymatic deficiency leads to severe metabolic derangement, manifested clinically as vomiting, dehydration, and acidosis progressing to seizures, coma, and death. The two phenotypic expressions are the acute severe and the chronic intermittent form. The acute severe phenotype typically results in death during early infancy, whereas patients with the chronic intermittent form are asymptomatic at baseline but have episodes of acute metabolic decompensation, usually in the setting of infection, physical exertion, or ingestion of protein-rich food. This case illustrates how inborn errors of metabolism resulting in organic acidemia can be manifested in adults and why the internist needs to be aware of them.

Isovaleric acidemia (IVA) is a rare inborn error of l-leucine catabolism, caused by deficiency of isovaleryl coenzyme A dehydrogenase. The natural history of IVA is characterized by severe metabolic derangement leading to coma, seizure, and death. With prompt diagnosis and institution of effective therapy, children with IVA can have normal growth and development.[1,2] Thus, internists must be able to recognize and treat these patients. The Online Mendelian Inheritance of Man (OMIM) number for IVA is 243500. OMIM is an invaluable tool in medical genetics and can be found at Although a review of the literature reveals only two cases of isovaleric acidemia in adults, these two cases illustrate how IVA can cause morbidity in adults.[3,4] We present the case of an 18-year-old man with severe nausea, vomiting, and obtundation due to metabolic decompensation of IVA.