Salicylates, principally acetylsalicylic acid (ASA or aspirin), remain a common cause of poisoning morbidity and mortality. In 2021 America’s Poison Centers recorded 18,309 cases mentioning ASA and it was among the top 25 causes of poisoning deaths.¹ Emergency physicians should be aware of 10 pitfalls in assessing and treating patients with salicylate poisoning.

Done With the Done Nomogram?

In the 1960s, A.K. Done published a nomogram to identify patients at high-risk for severe outcomes from salicylate poisoning. The graph was based on a patient’s serum salicylate concentration.² Later research found that the nomogram performed poorly for this purpose.³ Advanced age, high respiratory rate, and elevated lactate concentration appear to be better in identifying severe salicylate poisoning.⁴

Critical action 1: Do not use the Done nomogram to assess salicylate toxicity.

Critical action 2: Assess severity of poisoning with the patient’s age, the respiratory rate, and the lactate concentration in addition to the salicylate concentration.

Units Matter

Many medical laboratories measure serum salicylate using a colorimetric ferric nitrate or ferric chloride assay^5,6 and can report this information in different units. While other

countries use SI units (mmol/L), the two most common units in the U.S. are μg/mL (mg/L) and mg/dL. 1 mg/dL = 10 μg/mL = 10 mg/L = 0.072 mmol/L. A salicylate concentration of 100 μg/mL is at the lower end of the therapeutic range, but a salicylate concentration of 100 mg/dL is lethal without emergency dialysis.⁷ Henceforth, we express salicylate concentration in mg/dL.

Critical action: Know the units that your hospital laboratory uses.

Mind the Ions, Not the Gap

Salicylate is the “S” in MUDPILES, a mnemonic for causes of high anion gap metabolic acidosis. Salicylate ions sometimes interfere with the ion-selective electrodes of chemistry analyzers and may overestimate chloride ion concentration. This can cause pseudohyperchloremia, which can suppress the anion gap.^8–10 The anion gap may even be negative.^11–13

Critical action 1: Pay attention to a low bicarbonate level.

Critical action 2: Ignore a normal or low anion gap if the chloride is high.

Dextrose for Euglycemic Delirium

The brain needs glucose for energy. Salicylate uncouples oxidative phosphorylation—largely by drawing protons away from the mitochondrial intermembrane space. As this occurs, the brain consumes glucose more quickly while producing less adenosine triphosphate (ATP) and generating excess heat. This produces hypoglycorrhachia (low CSF glucose despite normal blood glucose), even when the blood glucose is normal.