Last updated: Monday, 25, October, 2010
CausesAppropriate Tests

Blood gases; electrolytes, anion gap, creatinine - plasma, urea - plasma. See also Alkalosis.

Metabolic acidosis

Defined as acidosis with a negative base excess and decreased bicarbonate.

Increased anion gap

Renal failure


Hydroxybutyrate is the preferred test, rather than acetoacetate.

Lactic acidosis

Unexplained acidosis in childhood

See Organic acidaemias.


Serum and urine assays, as appropriate.

  • Salicylate

Salicylate, lactate.

  • Methanol

Methanol (see under Alcohols).

  • Ethylene glycol

Glycol, oxalate – urine.

Normal anion gap

Hyperchloraemic acidosis.

Renal tubular acidosis

Intestinal bicarbonate loss, especially

Compensatory, especially

In primary respiratory alkalosis.

Respiratory acidosis

Defined as acidosis with an increased pCO2.

Respiratory failure (acute/chronic)


In primary metabolic Alkalosis.