Ethylene glycol poisoning

This week we reviewed an approach to acid-base disorders. The DDx for an anion gap (AG) acidosis includes 
1) lactate - type A and B
2) ketones - DKA, starvation, alcohol
3) uremia
4) toxic ingestions - salicylates, toxic alcohols like methanol and ethylene glycol

- Ethylene glycol is a parent compound that is a measured osmole, and will contribute to an osmolar gap (but not the AG). The toxic metabolite, glycolate, will contribute to the anion gap (but not the osmolar gap). The goal is to prevent end-organ damage from glycolate, the compound that causes renal failure and CNS toxicity

- Treatment of overdoses:
Stability: Always begin with the ABCS! (Consider the universal antidotes for all patients)
Decontamination: Not a big role for activated charcoal here
Excretion: High rates of IV fluid, consider bicarbonate infusion if acidemic
Antidotes: Fomepizole or IV ethanol binds to alcohol dehydrogenase, preventing conversion of EG to glycolate. Thiamine and pyroxidine are co-factors that help metabolize glycolic acid to non-toxic glycine. Similarly, folinic acid is a co-factor given for methanol poisoning
Hemodialysis: Assess on a case-by-case basis, but may be indicated with significant acidemia (pH < 7.3), end-organ damage, or an EG level > 8.1 mmol/L (or methanol > 15.6 mmol/L)

Here is a great NEJM review article on the treatment of ethylene glycol and methanol poisoning