What testing is needed if ethylene glycol and propylene glycol are found in water?

Testing for Ethylene Glycol and Propylene Glycol in Water

If ethylene glycol and propylene glycol are detected in water, no specific medical testing is needed unless there is evidence of human ingestion or exposure with clinical symptoms.

Context: Environmental vs. Clinical Concern

The presence of these glycols in water represents an environmental contamination issue, not an automatic indication for medical testing 1, 2. Testing becomes relevant only when there is:

• Documented or suspected ingestion of contaminated water 3
• Clinical symptoms suggestive of toxic alcohol poisoning 4
• Known exposure with concern for toxicity 5

When Medical Testing IS Indicated

Clinical Scenarios Requiring Laboratory Evaluation

If someone has consumed contaminated water and presents with concerning features, obtain:

Immediate laboratory studies:

• Serum ethylene glycol concentration (if available within 2-4 hours) 3
• Serum glycolate concentration (the toxic metabolite; more predictive of outcomes than ethylene glycol itself) 3
• Osmolal gap (calculated as measured osmolality minus calculated osmolarity) 3, 5
• Anion gap (calculated as Na+ + K− − Cl− − HCO3−) - the best surrogate marker when glycolate assays are unavailable 3
• Arterial blood gas to assess for metabolic acidosis 4
• Basic metabolic panel to evaluate renal function 4
• Urinalysis to look for calcium oxalate crystals (specific to ethylene glycol toxicity) 5, 4

Critical Thresholds for Action

The EXTRIP workgroup strongly advocates for rapid (2-4 hour) hospital availability of glycolate and ethylene glycol measurements to permit precise diagnosis and avoid unnecessary treatments 3.

Treatment thresholds based on laboratory findings:

• Anion gap >27 mmol/L: Strong indication for extracorporeal treatment 3
• Glycolate concentration >12 mmol/L: Strong indication for extracorporeal treatment (mortality rises substantially above this level) 3
• Osmolal gap >50: Consider extracorporeal treatment if fomepizole is being used 3, 5
• Ethylene glycol concentration >50 mg/dL: Consider hemodialysis in addition to fomepizole 4

When Medical Testing is NOT Needed

For asymptomatic individuals with potential exposure to contaminated water:

• No testing is required if there are no symptoms and no confirmed significant ingestion 5
• A normal osmolal gap (0-12 mOsm/kg H₂O) effectively rules out significant recent ethylene glycol ingestion when there is no clinical suspicion 5

Important caveat: The osmolal gap may be normal if ethylene glycol has already been metabolized, so clinical suspicion and anion gap must also be considered 3.

Propylene Glycol Considerations

Propylene glycol is significantly less toxic than ethylene glycol and is commonly found in hospitalized patients due to iatrogenic administration in medications like activated charcoal and intravenous lorazepam 6. It can contribute to an elevated osmolal gap but rarely requires specific treatment 6.

Environmental Water Testing

For the water source itself, specialized analytical methods exist:

• LC/ESI-MS/MS can detect glycols at concentrations as low as 1.9-6.1 ng/mL in various water matrices 1
• HPLC/MS with UV detection after derivatization with benzoyl chloride 2

These environmental tests assess water quality but do not replace clinical assessment of exposed individuals 1, 2.

Immediate Action Algorithm

If contaminated water is discovered:

1. Assess for symptomatic individuals (altered mental status, visual disturbances, seizures, metabolic acidosis) 5, 4
2. If symptomatic or confirmed significant ingestion: Obtain full laboratory panel as outlined above 3, 4
3. Begin fomepizole immediately upon suspicion based on history, anion gap metabolic acidosis, increased osmolar gap, visual disturbances, or oxalate crystals in urine 4
4. If asymptomatic with no confirmed ingestion: No medical testing required; focus on environmental remediation 5