From the Guidelines
Toxic alcohol ingestions, including methanol, ethylene glycol, and isopropanol, are associated with several electrolyte abnormalities, most notably an elevated anion gap metabolic acidosis, as evidenced by a study published in 2023 1.
Key Electrolyte Abnormalities
- Elevated anion gap metabolic acidosis: This occurs as the alcohols are metabolized to acidic compounds like formic acid (methanol) and glycolic/oxalic acids (ethylene glycol) 1.
- Osmolal gap elevation: Frequently observed early in the course of poisoning before significant metabolism has occurred.
- Hypocalcemia: Particularly associated with ethylene glycol poisoning due to calcium oxalate crystal formation, which can lead to tetany and cardiac arrhythmias, with a median lowest total calcium concentration of 2.1 mmol/L in patients with ethylene glycol poisoning 1.
- Hypokalemia: May develop as a compensatory response to acidosis as hydrogen ions move into cells and potassium shifts out.
- Hypophosphatemia: Can occur with prolonged toxic alcohol exposure.
- Hypomagnesemia: Sometimes accompanies ethylene glycol poisoning due to chelation with oxalate.
Clinical Implications
These electrolyte disturbances contribute significantly to the morbidity and mortality of toxic alcohol ingestions, with the acidosis being particularly dangerous as it can lead to cardiovascular collapse, CNS depression, and multi-organ failure if not promptly corrected with appropriate treatments like fomepizole or ethanol infusion, sodium bicarbonate for severe acidosis, and potentially hemodialysis for severe cases, as supported by the evidence that mortality in patients with an anion gap over 28 mmol/L was much higher (20.4%) 1.
Treatment Considerations
Treatment should focus on correcting the acidosis and managing the underlying cause of the electrolyte imbalances, with fomepizole (15 mg/kg loading dose followed by 10 mg/kg every 12 hours) or ethanol infusion, and sodium bicarbonate for severe acidosis being potential treatment options 1. Hemodialysis may also be necessary for severe cases, particularly those with high glycolate concentrations or significant acid-base disturbances, as indicated by a study that showed acidemia was corrected quickly in most cases receiving high-efficiency hemodialysis, usually within four hours 1.
From the FDA Drug Label
The diagnosis of these poisonings may be difficult because ethylene glycol and methanol concentrations diminish in the blood as they are metabolized to their respective metabolites Hence, both ethylene glycol and methanol concentrations and acid base balance, as determined by serum electrolyte (anion gap) and/or arterial blood gas analysis, should be frequently monitored and used to guide treatment Glycolate and oxalate are the metabolic byproducts primarily responsible for the metabolic acidosis and renal damage seen in ethylene glycol toxicosis. Formic acid is primarily responsible for the metabolic acidosis and visual disturbances (e.g., decreased visual acuity and potential blindness) associated with methanol poisoning.
The electrolyte abnormalities associated with toxic alcohol ingestions, such as methanol and ethylene glycol, include:
- Metabolic acidosis: caused by the accumulation of toxic metabolites, including glycolic and oxalic acids (ethylene glycol intoxication) and formic acid (methanol intoxication)
- Anion gap metabolic acidosis: as determined by serum electrolyte analysis
- Electrolyte imbalances: due to renal damage and metabolic acidosis, although specific electrolyte imbalances are not detailed in the provided text 2, 2
From the Research
Electrolyte Abnormalities in Toxic Alcohol Ingestions
The ingestion of toxic alcohols, such as methanol, ethylene glycol, and isopropanol, can lead to significant electrolyte abnormalities. Some of the key electrolyte abnormalities associated with these ingestions include:
- Metabolic acidosis, which can lead to an increased anion gap 3, 4, 5
- Hyperchloremic metabolic acidosis, as seen in butoxyethanol ingestion 6
- Increased osmolal gap, which can be used as a diagnostic tool for methanol and ethylene glycol poisoning 5, 7
- High-anion-gap metabolic acidosis, which can occur in conjunction with an increased serum osmolal gap 7
Specific Electrolyte Abnormalities
Some specific electrolyte abnormalities that can occur with toxic alcohol ingestions include:
- Hypokalemia, which can occur due to the metabolic acidosis and increased renal excretion of potassium
- Hyperkalemia, which can occur in severe cases of metabolic acidosis
- Hypocalcemia, which can occur due to the increased deposition of calcium in tissues
Diagnostic Approach
The diagnosis of electrolyte abnormalities in toxic alcohol ingestions typically involves a combination of laboratory tests, including: