Template:Toxic Alcohols Anion/Osmolar Gaps: Difference between revisions

Latest revision as of 19:42, 12 March 2026

Toxic Alcohols Anion/Osmolar Gaps

Substance	Osmolar gap	Metabolic acidosis	Anion gap	Ketones	Ca Oxalate crystals	Reduced vision	Management
Ethanol	+	+/- (if ketoacidosis)	+/- (if ketoacidosis)	+/-	-	-	Mainly supportive
Ethylene glycol	+ (early)*	+	+	-	+	-	Fomepizole, Thiamine, Pyridoxine, +/- Dialysis
Methanol	+ (early)*	+	+	-	-	+	Fomepizole or ethanol, Folinic acid/Folic acid, +/- Dialysis
Isopropyl alcohol	+	-	-	+ (acetonemia without acidosis)	-	-	Mainly supportive, +/- Dialysis if severe
Propylene glycol	+	+	+ (lactic acidosis)	-	-	-	D/C offending agent (e.g. IV lorazepam/diazepam), supportive, +/- Dialysis

Osmolar gap → Anion gap transition: For all toxic alcohols, the osmolar gap is elevated early (parent compound present) and decreases over time as the alcohol is metabolized into organic acid metabolites, which then produce an anion gap metabolic acidosis. A normal osmolar gap does NOT exclude toxic alcohol ingestion if presentation is delayed.

Key distinguishing features

Isopropyl alcohol: The only toxic alcohol that causes ketosis without metabolic acidosis (metabolized to acetone, not an organic acid)

Ethylene glycol: Ca oxalate crystals in urine + anion gap metabolic acidosis + renal failure

Methanol: Visual disturbances (blurred vision, "snowfield" vision, blindness) + anion gap metabolic acidosis + optic disc hyperemia on fundoscopy

@@ Line 1: / Line 1: @@
 ===[[Toxic Alcohols]] Anion/Osmolar Gaps===
 {| class="wikitable"
-! [[Osmolar gap]] !! [[Metabolic acidosis]] !! Osmolar gap !! [[Anion gap]] !! Ketones !! Ca Oxolate stones !! Reduced vision !! Management
+! Substance !! [[Osmolar gap]] !! [[Metabolic acidosis]] !! [[Anion gap]] !! Ketones !! Ca Oxalate crystals !! Reduced vision !! Management
 |-
-| [[Ethanol ]]|| + || + || + (if ketoacidosis) || + || - ||  || Mainly supportive
+| [[Ethanol]] || + || +/- (if ketoacidosis) || +/- (if ketoacidosis) || +/- || - || - || Mainly supportive
 |-
-| [[Ethylene glycol]] || + || + || + || - || + || - || [[Fomepizole]], [[Thiamine]], [[Pyridoxine]], +/- Dialysis
+| [[Ethylene glycol]] || + (early)* || + || + || - || + || - || [[Fomepizole]], [[Thiamine]], [[Pyridoxine]], +/- Dialysis
 |-
-| [[Methanol]] || + || + (early on, then disappears) || + || - || - || + || [[Fomepizole]] or ethanol, Folinic acid, +/- Dialysis
+| [[Methanol]] || + (early)* || + || + || - || - || + || [[Fomepizole]] or ethanol, [[Folic Acid|Folinic acid/Folic acid]], +/- Dialysis
 |-
-| [[Isopropyl alcohol]] || - || + || - || + || - || + || Mainly supportive
+| [[Isopropyl alcohol]] || + || - || - || + (acetonemia without acidosis) || - || - || Mainly supportive, +/- Dialysis if severe
 |-
-| Propylene gylcol || + || + (initially) || + (converted to lactate) || - || - || - ||
+| [[Propylene glycol]] || + || + || + (lactic acidosis) || - || - || - || D/C offending agent (e.g. IV lorazepam/diazepam), supportive, +/- Dialysis
 |}
+;*'''Osmolar gap → Anion gap transition:''' For all toxic alcohols, the osmolar gap is elevated '''early''' (parent compound present) and '''decreases over time''' as the alcohol is metabolized into organic acid metabolites, which then produce an anion gap metabolic acidosis. A '''normal osmolar gap does NOT exclude''' toxic alcohol ingestion if presentation is delayed.
+;Key distinguishing features:
+;*'''Isopropyl alcohol:''' The '''only''' toxic alcohol that causes ketosis '''without''' metabolic acidosis (metabolized to acetone, not an organic acid)
+;*'''Ethylene glycol:''' Ca oxalate crystals in urine + anion gap metabolic acidosis + renal failure
+;*'''Methanol:''' Visual disturbances (blurred vision, "snowfield" vision, blindness) + anion gap metabolic acidosis + optic disc hyperemia on fundoscopy