Organic acidaemias

Last updated: Friday, 24, December, 2010
Key InformationAppropriate Tests

A possible genetic basis should be considered in children with metabolic acidosis not attributable to another disorder, especially if the acidosis cannot be explained by elevated lactate and/or hydroxybutyrate.

Blood gases - arterial or venous.

Organic acids - urine (collected during acidotic episode); a normal result, when not acutely ill, does not exclude these disorders. In some diseases (eg, biotinidase deficiency) metabolic acidosis may not occur, but the abnormal organic acids can be detected in the urine.

Identification of the specific disorder depends on the pattern of organic acids excreted during attacks.

Ammonium and glucose should be measured, as many organic acidaemias are associated with hyperammonaemia and/or hypoglycaemia.

See also Hyperammonaemia, Hypoglycaemia

Naming of specific disorders is usually based on the acid(s) excreted or the deficient enzyme(s).

Specific disorders

Genetic lactic acidosis 

L-lactate, pyruvate may assist in determining the cause of lactic acidosis.

Genetic ketoacidosis 

Hydroxybutyrate.

Methylmalonic acidaemia 

Homocysteine (some types also have homocystinuria).

Medium chain acyl CoA dehydrogenase deficiency 

Molecular genetics.

Maple syrup urine disease 

Amino acids (leucine, isoleucine, valine) - urine.

Acute manifestations

Unexplained metabolic acidosis

See Acidosis - metabolic

Hypoglycaemia

Hyperammonaemia

Unusual body odour

Chronic manifestations

Psychomotor regression

Failure to thrive

Osteoporosis