Organic acidaemias

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).

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

Homocysteine (some types also have homocystinuria).

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