LAUSR

We’d like to congratulate Moss et al. on publishing their study, Salicylate Toxicity After Undetectable Serum Salicylate Concentration: A Retrospective Cohort Study [1]. Kinetics in overdose rarely mirror those found after therapeutic dosing of many medications. Because of erratic and unpredictable absorption, significant salicylate ingestion could rightly be labeled the quintessential poster child of this phenomenon. We frequently care for salicylate-poisoned patients whose concentrations continue to rise over time, after both therapeutic and supratherapeutic salicylate concentrations are initially obtained. We would like to add to this discussion two cases where initial undetectable serum salicylate concentrations rose to severely toxic concentrations beyond the peak of 61mg/dL reported in Moss’ case series. Both cases required hemodialysis and one resulted in a fatality. Case 1 was a 14-year-old girl who reportedly ingested ibuprofen and escitalopram. Initial vital signs and workup were unremarkable and her salicylate concentration was undetectable. A single dose of activated charcoal was administered and she was admitted for observation. While being monitored, she subsequently developed abdominal discomfort, tachypnea, diaphoresis, and tinnitus. A repeat salicylate concentration 29 h post presentation was 96mg/dL. The patient was transferred to another facility for hemodialysis, and upon arrival, a repeat concentration was 98mg/dL. A post dialysis salicylate concentration was undetectable and she received no subsequent activated charcoal or alkalinization. She was medically cleared and transferred to an inpatient psychiatric facility for care. Case 2 was a 42-year-old man who reportedly ingested quetiapine, diphenhydramine, and baby aspirin in unknown amounts. He presented to the hospital confused, with normal vital signs, and an undetectable salicylate concentration. A single dose of activated charcoal was administered in the emergency department. Because of a history of aspirin ingestion, repeat salicylate concentrations were pursued. Over time, the concentrations (mg/dL) were 17, 19, 23, and 61. A repeat dose of activated charcoal was administered and alkalinization was commenced. Subsequent concentrations were 100 and 98mg/dL. A third dose of activated charcoal was administered and hemodialysis was initiated. The concentration dropped to 67mg/dL, however he developed tachypnea and altered mental status and had a reported salicylate concentration of 123mg/dl. He was emergently intubated and unfortunately suffered irreversible cardiac arrest and death. We’d like to highlight the understanding that salicylate poisoning may still be possible despite a concentration that is initially undetectable. Repeating salicylate concentrations is of paramount importance, especially when suspicion for a true salicylate ingestion is high. While this decision is evident when initial concentrations are detectable, an initial concentration that is undetectable creates a dilemma as to if or when a subsequent concentration should be entertained. Close reassessment, repeat electrolytes, and pursuing further questions regarding the history may assist in this decisionmaking. Case 1 required a measured salicylate concentration because her symptomatology evolved with features consistent with salicylate poisoning (e.g. tachypnea, diaphoresis, and tinnitus). Case 2 warranted subsequent salicylate concentrations because he had a history of ingesting aspirin in overdose. The decision as to how far out a salicylate concentration should be entertained (after an initially undetectable concentration) should be made on a case by case basis.