[Diagnosis in metabolic acidosis of unknown origin].

BACKGROUND: Obtaining a precise diagnosis in patients presenting with metabolic acidosis of unknown origin is difficult. Poisoning with methanol or ethylene glycol should be suspected in cases with a combined increase of osmolal and anion gaps.

MATERIALS AND METHODS: Retrospectively we have compared the methanol and ethylene glycol values in poisoned patients with their osmolal gaps. The anion gaps are compared to the toxic anions measured.

RESULTS: There were good correlations between serum alcohols and osmolal gaps and between toxic metabolites and anion gaps.

INTERPRETATION: The osmolal and the anion gaps are both helpful tools in the diagnosis of patients with metabolic acidosis of unknown origin, especially for identifying patients poisoned with methanol or ethylene glycol.