Undetectable Acetaminophen Levels
Acetaminophen overdose is the most common cause of acute liver failure in the United States. A recent publication by Leventhal et al. demonstrated that more than half of patients who presented to the hospital with acetaminophen induced liver injury or acute liver failure had undetectable acetaminophen levels.
The study included 434 patients at 22 tertiary care hospitals in the United States who were admitted with acute liver injury or acute liver failure. Acetaminophen was detected in 47.7% of patients at admission. Among the patients with detectable acetaminophen, 51% reported unintentional overdose while 43% reported suicide attempt. Among the patients with undetectable acetaminophen, 63% reported unintentional overdose compared to 30% who reported suicidal overdose.
Overall survival at 21 days was 92% for patients with undetectable levels and 82% for patients with detectable levels. Transplant free survival rate was 86% for patients with undetectable levels and 72% for patients with detectable levels.
This investigation indicates that acetaminophen levels cannot be relied upon to determine the etiology of acute liver injury or acute liver failure. Acetaminophen toxicity should not be ruled out solely because of undetectable levels. Patients who give a history of acetaminophen ingestion should be treated with N-acetylcysteine when ALT levels exceed 2000 IU/L.
Reference
Leventhal TM et al. Acetaminophen is Undetectable in Plasma from More Than Half of Patients Believed to Have Acute Liver Failure Due to Overdose. Clinical Gastroenterology and Hepatology 2019; https://doi.org/10.1016/j.cgh.2019.01.040
