Patterns of transaminase elevation in rhabdomyolysis versus acetaminophen toxicity

Transaminase elevations can occur from liver injury or in the setting of rhabdomyolysis. The goal of this study is to evaluate indices that could differentiate acetaminophen toxicity from muscle injury in the setting of transaminase elevations.

A retrospective chart review of consecutive cases reported to our regional poison center. Patients with transaminase (AST and ALT) elevation were grouped as those with acetaminophen exposure (AT) and those with elevated creatine phosphokinase (CPK) without evidence of acetaminophen exposure (RHB).

Of the 345 patients included in the study, elevated AST/ALT levels were attributed to rhabdomyolysis in 168 patients and attributed to acetaminophen toxicity in 177 patients. The median AST: ALT values also differed between groups, with patients in the RHB group had higher median ratios (p < 0.001). Using an AST: ALT value of 2.02 as a diagnostic cutoff produced a specificity of 0.52 (95% CI: 0.37, 0.64) and sensitivity of 0.84 (95% CI: 0.73, 0.94) for acetaminophen detection in the test dataset (N = 104).

Elevated transaminases due to liver injury from acetaminophen ingestion had a different pattern than elevated transaminases due to rhabdomyolysis. Lower AST:ALT ratios were found in acetaminophen cases, however, the specificity using a ratio threshold of ≤1 would be 83%.