Congenital lactic acidosis and mitochondrial disease – when to suspect and how to manage

Congenital lactic acidosis presents in the newborn period, usually in a symptomatic infant (hypotonia, weakness, respiratory failure), and has a poor prognosis. The underlying aetiology may be an inborn error of metabolism, including Lethal Infantile Mitochondrial Disease (LIMD). In LIMD, lactic acidosis arises because poorly functioning mitochondria do not allow oxidation of pyruvate, which in turn leads to an accumulation of lactate as a by-product of anaerobic metabolism. Lactic acidosis may be the first clue to an underlying mitochondrial disease. In this article we will review the physiology of lactate metabolism, highlight clinical features associated with congenital lactic acidosis, and explore management options in order to make a diagnosis of mitochondrial disease.