Delayed high anion gap metabolic acidosis after a suicide attempt: case report

Abstract

Background: Metabolic acidosis, especially when induced by multiple drug poisoning, often makes rapid and accurate differential diagnosis of the condition challenging.

Methods: We closely followed anion and osmolal gaps to differentiate among the aetiologies of metabolic acidosis caused by poisoning with unknown drugs.

Results: The patient was admitted to our emergency department (ED) in an alert and consciousness state after attempting suicide by ingestion of an uncertain quantity of rodenticides combined with an unknown liquid. Initially, metabolic acidosis (pH7.23) with normal anion gap (12.8) was observed. However, a change in consciousness and hypotension subsequently developed 6h later, combined with severe metabolic acidosis (pH7.16), high anion gap (25.5), and high osmolal gap (83). A presumed diagnosis of methanol intoxication was suspected. After 4h of high-flux haemodialysis (HD), the serum bicarbonate returned to 23 mmol/l, and the patient regained consciousness. The serum level of methanol before HD was 193.8 mg/dl. The patient was discharged nine days later without sequelae.

Conclusions: Delayed high anion gap metabolic acidosis may occur in the ED. Frequent monitoring of anion and osmolal gaps is a feasible method to perform a rapid differential diagnosis, particularly in response to drug poisoning.

Keywords: Anion gap; Drug poisoning; Metabolic acidosis; Osmolal gap.