Toxic Alcohols

The answer first

Toxic alcohol poisoning — ethylene glycol and methanol most commonly — is a clinical and biochemical emergency characterised by a rapidly evolving high-anion-gap metabolic acidosis, an elevated osmol gap early in the course, and target-organ injury (acute kidney injury in ethylene glycol toxicity; optic neuropathy and basal ganglia injury in methanol toxicity); it is managed by the immediate administration of an alcohol dehydrogenase inhibitor (fomepizole preferred, ethanol where fomepizole is unavailable), cofactor therapy (folate for methanol, thiamine and pyridoxine for ethylene glycol) to direct metabolism away from toxic metabolites, haemodialysis for moderate to severe cases, and meticulous correction of the metabolic acidosis. ^{[1] [2]} The answer-first decision at the bedside is to suspect the diagnosis on the basis of an unexplained high-anion-gap metabolic acidosis with an elevated osmol gap, to give fomepizole empirically before the serum level returns, and not to wait for confirmation in the deteriorating patient. ^{[1] [6]}

For the FRACP candidate, this is a high-yield topic because it tests integrated acid–base interpretation, nephrology (dialysis indications and timing), toxicology, neurology (optic neuropathy), and emergency decision making. Lead with the decision (the patient has a high-anion-gap metabolic acidosis with an elevated osmol gap consistent with toxic alcohol poisoning; I am giving fomepizole now, starting cofactors, contacting the dialysis service, and sending a confirmatory serum methanol and ethylene glycol level), defend the antidote and dialysis thresholds with the cited evidence, and name the trap (a normal or low osmol gap does not exclude toxic alcohol poisoning once metabolism is established, because the osmotically active parent alcohol has been converted to the acid). ^{[1] [7]}

References12ShowHide

1. [1]Brent J, McMartin K, Phillips S, Burkhart KK, et al. Fomepizole for the treatment of ethylene glycol poisoning. Methylpyrazole for Toxic Alcohols Study Group N Engl J Med, 1999.PMID 10080845
2. [2]Brent J, McMartin K, Phillips S, et al. Fomepizole for the treatment of methanol poisoning N Engl J Med, 2001.PMID 11172179
3. [3]Zakharov S, Pelclova D, Navratil T, Belacek J, et al. Fomepizole versus ethanol in the treatment of acute methanol poisoning: Comparison of clinical effectiveness in a mass poisoning outbreak Clin Toxicol (Phila), 2015.PMID 26109326
4. [4]Ghannoum M, Gosselin S, Hoffman RS, et al. Extracorporeal treatment for ethylene glycol poisoning: systematic review and recommendations from the EXTRIP workgroup Crit Care, 2023.PMID 36765419
5. [5]Wang C, Hiremath S, Sikora L, et al. Kidney outcomes after methanol and ethylene glycol poisoning: a systematic review and meta-analysis Clin Toxicol (Phila), 2023.PMID 37293897
6. [6]Beauchamp GA, Valento M Toxic Alcohol Ingestion: Prompt Recognition And Management In The Emergency Department Emerg Med Pract, 2016.PMID 27538060
7. [7]Ng PCY, Long BJ, Davis WT, et al. Toxic alcohol diagnosis and management: an emergency medicine review Intern Emerg Med, 2018.PMID 29427181
8. [8]Inman B, Maddry JK, Ng PC, et al. High risk and low prevalence diseases: Toxic alcohol ingestion Am J Emerg Med, 2023.PMID 36796238
9. [9]Sharma R, Marasini S, Sharma AK, et al. Methanol poisoning: ocular and neurological manifestations Optom Vis Sci, 2012.PMID 22127151
10. [10]McKellar MJ, Hidajat RR, Elder MJ Acute ocular methanol toxicity: clinical and electrophysiological features Aust N Z J Ophthalmol, 1997.PMID 9296298
11. [11]Hoegberg LCG, Shepherd G, Wood DM, et al. Systematic review on the use of activated charcoal for gastrointestinal decontamination following acute oral overdose Clin Toxicol (Phila), 2021.PMID 34424785
12. [12]Kruse JA Methanol poisoning Intensive Care Med, 1992.PMID 1469176