Asymptomatic alanine aminotransferase elevations with therapeutic doses of acetaminophen.

While acetaminophen overdose has been recognized as a cause of alanine aminotransferase (ALT) elevations for over 40 years, recent studies have reported asymptomatic ALT elevations in research subjects who are administered with therapeutic doses (4 g/d or less) of acetaminophen for more than 4 days. While the clinical course of these elevations is not completely defined, available evidence suggests that even in high risk groups the elevations are not accompanied by evidence of hepatic dysfunction and that resolve if treatment is continued. Toxicologists should consider therapeutic acetaminophen use as a cause of ALT elevation. Further study of the mechanism of ALT elevations may provide new insight into other causes of drug-induced liver injury and hepatic adaptation.