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Toxicology – Ethylene Glycol (Antifreeze Poisoning)
Source
Ethylene glycol is commonly found in antifreeze and hydraulic brake fluids. Its sweet taste increases the risk of accidental ingestion, especially in children and animals.
Typical Presentation
Patients often present hours after ingestion with progressive symptoms that evolve in stages, beginning with neurological and gastrointestinal complaints and later affecting the heart, lungs, and kidneys.
Clinical Features
Ethylene glycol toxicity typically progresses through three stages:
Ethylene glycol itself is not highly toxic, but it is metabolized into harmful compounds such as glycolic acid and oxalic acid. Glycolic acid causes severe metabolic acidosis and cellular damage, while oxalic acid binds calcium to form crystals that deposit in the kidneys, leading to renal failure.
Management
Treatment focuses on preventing toxic metabolite formation and enhancing elimination:
Source
Ethylene glycol is commonly found in antifreeze and hydraulic brake fluids. Its sweet taste increases the risk of accidental ingestion, especially in children and animals.
Typical Presentation
Patients often present hours after ingestion with progressive symptoms that evolve in stages, beginning with neurological and gastrointestinal complaints and later affecting the heart, lungs, and kidneys.
Clinical Features
Ethylene glycol toxicity typically progresses through three stages:
- Stage I (30 min–12 hrs): Early symptoms resemble alcohol intoxication, including confusion, dizziness, slurred speech, nausea, vomiting, and abdominal pain.
- Stage II (12–36 hrs): Cardiopulmonary effects develop, including rapid heart rate, elevated blood pressure, rapid breathing, and severe metabolic acidosis. Low calcium levels may cause muscle spasms, tetany, and decreased reflexes. Serious complications include brain swelling, lung injury, and cardiovascular collapse.
- Stage III (24–72 hrs): Kidney injury becomes prominent, with decreased urine output, blood or protein in urine, electrolyte disturbances, and possible kidney failure.
Ethylene glycol itself is not highly toxic, but it is metabolized into harmful compounds such as glycolic acid and oxalic acid. Glycolic acid causes severe metabolic acidosis and cellular damage, while oxalic acid binds calcium to form crystals that deposit in the kidneys, leading to renal failure.
Management
Treatment focuses on preventing toxic metabolite formation and enhancing elimination:
- Fomepizole is the preferred antidote; it blocks alcohol dehydrogenase.
- Ethanol may be used if fomepizole is unavailable.
- Hemodialysis is indicated in severe cases to remove toxins and correct acidosis.
- Thiamine and pyridoxine help shift metabolism toward less harmful pathways.
- Sweet taste increases risk of accidental ingestion.
- Severe metabolic acidosis is a hallmark finding.
- Calcium oxalate crystals may be seen in urine.
- Kidney failure is a major late complication.
- Early treatment is critical to prevent irreversible damage.
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