What are the most common and significant intoxications that can be treated with hemodialysis (HD)?

Most Common and Significant Intoxications Treatable with Hemodialysis

The most common and clinically significant intoxications requiring hemodialysis are salicylates, lithium, methanol, and ethylene glycol, with hemodialysis being the preferred extracorporeal modality for all of these poisonings. 1, 2

Primary Dialyzable Intoxications

Salicylates (Aspirin)

• Salicylates are readily dialyzable by hemodialysis (Level of evidence B), making it the preferred extracorporeal treatment modality 3
• Hemodialysis is strongly recommended for severe salicylate poisoning with any of the following clinical features 3:
  • Altered mental status (regardless of salicylate level) 3
  • Acute respiratory distress syndrome requiring supplemental oxygen 3
  • Failure of standard therapy (alkalinization with bicarbonate) 3
• Concentration-based thresholds for hemodialysis 3:
  • >7.2 mmol/L (100 mg/dL): Strong recommendation for hemodialysis 3

  • 6.5 mmol/L (90 mg/dL): Conditional recommendation 3

  • Lower thresholds apply with impaired kidney function: >6.5 mmol/L (90 mg/dL) strongly recommended, >5.8 mmol/L (80 mg/dL) conditionally recommended 3
• Severe acidemia (pH <7.20) warrants consideration of hemodialysis even without other indications 3
• Mortality in reported cases was 11% among patients receiving extracorporeal treatment 3

Ethylene Glycol

• Ethylene glycol and its toxic metabolite glycolate are both dialyzable (Level of evidence B for ethylene glycol, C for glycolate) 3
• Strong recommendations for hemodialysis include 3:
  • Glycolate concentration >12 mmol/L OR anion gap >27 mmol/L 3
  • Severe clinical features: coma, seizures, or acute kidney injury 3
  • If using ethanol as antidote AND ethylene glycol >50 mmol/L OR osmol gap >50 3
• Conditional recommendations 3:
  • Glycolate concentration 8-12 mmol/L OR anion gap 23-27 mmol/L 3
  • If using fomepizole AND ethylene glycol >50 mmol/L OR osmol gap >50 3
• Cessation criteria: Stop hemodialysis when anion gap <18 mmol/L (strong) or ethylene glycol <4 mmol/L (25 mg/dL) (conditional) 3
• Overall mortality in analyzed cases was 18.7%, but only 3.6% in patients with glycolate ≤12 mmol/L 3

Methanol

• Methanol and its toxic metabolite formic acid are dialyzable 4, 1
• Hemodialysis is indicated when 4:
  • Methanol concentration ≥50 mg/dL 4
  • Significant or worsening metabolic acidosis 4
  • Renal failure 4
• Treatment should begin immediately upon suspicion based on anion gap metabolic acidosis, increased osmolar gap, visual disturbances, or documented methanol concentration >20 mg/dL 4
• In one series of 91 patients, mortality was 3.3%, with deaths associated with severe acidosis (pH ≤6.90), ventilator requirement, and coma/seizures on admission 5

Lithium

• Lithium is dialyzable and hemodialysis is recommended for severe lithium intoxication 1, 2, 6
• Indications typically include severe neurological symptoms, renal failure preventing adequate clearance, or very high lithium levels with clinical toxicity 2

Hemodialysis Modality Preferences

Intermittent hemodialysis is the preferred modality for all these intoxications over other extracorporeal treatments 3

Alternative Modalities (in order of preference when hemodialysis unavailable):

• For salicylates: Hemoperfusion is acceptable, followed by continuous renal replacement therapy (CRRT); exchange transfusion in neonates 3
• For ethylene glycol: CRRT is recommended if intermittent hemodialysis unavailable 3
• Peritoneal dialysis should NOT replace hemodialysis when the latter is available, as it adds minimal clearance (only 5% additional) with higher complication rates 3

Critical Pitfalls to Avoid

• Do not delay hemodialysis waiting for confirmatory toxin levels when clinical presentation (severe acidosis, altered mental status, end-organ damage) strongly suggests poisoning 4, 5
• Do not use clinical improvement alone as a reason to withhold hemodialysis in salicylate poisoning—concentrations >7.2 mmol/L warrant treatment regardless of symptoms 3
• Remember to adjust antidote dosing (fomepizole or ethanol) during hemodialysis, as these are dialyzable; increase fomepizole dosing frequency to every 4 hours during hemodialysis 3, 4
• Do not assume adequate treatment based solely on improving pH—continue hemodialysis until specific cessation criteria are met (anion gap normalization for ethylene glycol, undetectable or very low toxin levels) 3, 4

Other Potentially Dialyzable Intoxications

Additional poisonings where hemodialysis may be beneficial include theophylline, barbiturates, valproic acid, metformin, and carbamazepine, though these are less commonly encountered in clinical practice 1, 6