A 28-year-old woman is brought to the emergency department 4 hours after intentional ingestion of aspirin. She is tachypneic (RR 32/min), with altered mental status and a blood pH of 7.08 with anion-gap metabolic acidosis. Serum salicylate level is 118 mg/dL. The AEIOU mnemonic for dialysis indications is displayed. The structure marked **C** in the diagram represents a category of poisonings amenable to hemodialysis. Which of the following is the MOST appropriate indication for initiating hemodialysis in this patient?

Explanation

## Why "Salicylate level > 100 mg/dL acute, with severe acidosis and altered mental status" is right Salicylate (aspirin) overdose is a classic indication for hemodialysis, falling under the **C** (Intoxications) category of the AEIOU mnemonic. According to Harrison 21e, hemodialysis is indicated for acute salicylate poisoning when the serum level exceeds 100 mg/dL OR when there is persistent anion-gap metabolic acidosis (pH < 7.1) despite bicarbonate therapy, altered mental status, pulmonary edema, or other end-organ manifestations. This patient meets multiple criteria: salicylate 118 mg/dL (>100), pH 7.08 (<7.1), tachypnea, and altered mental status. Salicylates are dialyzable because they have low molecular weight (<500 Da), low protein binding, and are water-soluble—properties that make them amenable to hemodialysis. ## Why each distractor is wrong - **"Salicylate level > 60 mg/dL chronic, regardless of clinical symptoms"**: The 60 mg/dL threshold applies to *chronic* salicylate toxicity (e.g., chronic aspirin use in elderly patients), where symptoms may be subtle. In acute overdose, the threshold is 100 mg/dL, and clinical severity (acidosis, altered mental status) guides urgency. This option conflates acute and chronic thresholds. - **"Salicylate level > 80 mg/dL acute, even if pH remains > 7.2"**: While 80 mg/dL is concerning, the indication for hemodialysis in acute salicylate poisoning requires either level >100 mg/dL OR severe metabolic acidosis with end-organ signs. A pH >7.2 without other severe manifestations would typically be managed with supportive care and alkalinization alone, not immediate dialysis. - **"Salicylate level > 120 mg/dL acute, only if renal function is severely impaired"**: This option incorrectly restricts dialysis to patients with severe renal impairment. Hemodialysis is indicated for acute salicylate toxicity based on level and clinical severity *regardless* of baseline renal function. Renal impairment may worsen prognosis but is not a prerequisite for dialysis initiation. **High-Yield:** Acute salicylate overdose → dialyze if level >100 mg/dL OR pH <7.1 with altered mental status; chronic salicylate toxicity → dialyze if level >60 mg/dL. Salicylates are dialyzable because of low MW, low protein binding, and water solubility. [cite: Harrison 21e Ch 311 — Dialysis indications (AEIOU); Intoxications amenable to hemodialysis]