Negative Predictive Value of Acetaminophen Concentrations Within Four Hours of Ingestion

Abstract

An APAP concentration of <100 μg/mL obtained between 1 and 4 hours after ingestion has a high NPV for excluding toxic ingestion. We do not recommend reliance on concentrations obtained between 1 and 4 hours to exclude toxicity, because of a potential false-negative rate of 6.5%.