What are the dialyzable intoxications, in order of frequency and/or treatment success, that benefit from hemodialysis?

Dialyzable Intoxications: Ranked by Frequency and Treatment Success

The most commonly dialyzed intoxications in clinical practice are salicylates, lithium, methanol, and ethylene glycol, with hemodialysis being highly effective for all four when appropriately indicated. 1, 2

Most Common Dialyzable Intoxications (In Order of Frequency)

1. Salicylates (Aspirin)

• Most frequently dialyzed intoxication in emergency departments, representing approximately 50% of hemodialysis cases for poisoning 3, 2
• Highly dialyzable with extracorporeal clearance exceeding 100 mL/min using modern high-flux membranes 3
• Mortality rate of 11% when treated with extracorporeal treatment, with 1% permanent sequelae 3
• Hemodialysis is strongly recommended (Level 1D) when salicylate concentration >7.2 mmol/L (100 mg/dL) 3, 4
• Suggested for levels >6.5 mmol/L (90 mg/dL), with lower thresholds (>5.8 mmol/L or 80 mg/dL) in patients with impaired kidney function 3, 4

2. Lithium

• Second most common dialyzable intoxication, accounting for approximately 27% of hemodialysis cases in poisoning series 2
• Hemodialysis is effective and rapid for removing lithium in severely toxic patients 5
• No specific antidote exists, making hemodialysis the primary definitive treatment beyond supportive care 5
• Treatment should include urea, mannitol, and aminophylline to increase lithium excretion alongside hemodialysis 5

3. Methanol

• Third most common, representing approximately 55% of toxic alcohol cases requiring dialysis 2
• Mortality rate of 18.7% even with appropriate treatment including hemodialysis and antidotes 3
• Hemodialysis strongly recommended when methanol concentration >50 mg/dL with ethanol as antidote, or >62 mg/dL without antidote 6, 1
• High-flux hemodialysis corrects metabolic acidosis rapidly, typically within 4 hours 7
• Fomepizole dosing must be increased to every 4 hours during hemodialysis due to extensive dialyzability 6, 4

4. Ethylene Glycol

• Fourth most common, accounting for approximately 18% of toxic alcohol dialysis cases 2
• Hemodialysis strongly recommended when glycolate concentration >12 mmol/L or anion gap >27 mmol/L 3, 4
• Suggested when glycolate 8-12 mmol/L or anion gap 23-27 mmol/L 3, 4
• Mortality approaches zero when glycolate <12 mmol/L or anion gap <28 mmol/L with appropriate treatment 3
• Fomepizole requires dosing every 4 hours during hemodialysis to maintain adequate alcohol dehydrogenase inhibition 6, 4

Additional Dialyzable Intoxications (Less Common)

5. Theophylline

• Hemoperfusion preferred over hemodialysis for this intoxication 8
• Patients with severe acute theophylline intoxication benefit significantly from hemoperfusion 8

6. Barbiturates

• Hemoperfusion achieves very high clearance rates, though clinical benefit remains debated 8
• Less commonly requires dialysis in modern practice due to declining use 8

7. Isopropanol (Isopropyl Alcohol)

• Readily dialyzable with ideal characteristics for hemodialysis intervention 9
• Less commonly requires dialysis as it is less toxic than methanol or ethylene glycol 9

Hemodialysis Modality Preferences

Intermittent hemodialysis is the preferred modality for all dialyzable intoxications when available 4

• Use high-flux membranes with blood flow rates >250 mL/min for optimal toxin removal 7
• Continuous renal replacement therapy (CRRT) is second-line when intermittent hemodialysis unavailable 3, 4
• Hemoperfusion is preferred specifically for theophylline and may be considered for barbiturates 8
• Peritoneal dialysis is inadequate with clearance <8 mL/min for most toxins, several-fold inferior to hemodialysis 3

Critical Treatment Pitfalls to Avoid

• Never delay hemodialysis for salicylates >7.2 mmol/L based on clinical improvement alone, as subsequent deterioration is common and unpredictable 3, 4
• Do not assume adequate antidote coverage during hemodialysis without increasing fomepizole or ethanol dosing frequency 6, 4
• Avoid using normal saline as primary resuscitation fluid in toxic alcohol poisonings, as it worsens hyperchloremic acidosis 10
• Do not stop hemodialysis based on improving pH alone; continue until specific cessation criteria met (anion gap <18 mmol/L for ethylene glycol, salicylate undetectable or <20 mg/dL) 3, 4
• Never use polycarbonate syringes or needles when administering fomepizole, as drug-plastic interaction compromises syringe integrity 6

Hemodialysis Cessation Criteria

For ethylene glycol: Stop when anion gap <18 mmol/L, ethylene glycol <4 mmol/L (25 mg/dL), and acid-base abnormalities corrected 3

For methanol: Stop when methanol concentration <20 mg/dL and patient asymptomatic with normal pH 6

For salicylates: Continue until salicylate concentration undetectable or very low with clinical improvement 4