Bottom line: Although ALT is present in many organs, including heart and muscle, it is most concentrated in the liver. While elevated ALT has been reported in patients with rhabomyolysis, but no apparent liver injury, elevated ALT is more commonly found and is more specific for liver injury than elevated aspartate aminotransaminase (AST).
Summary: Table 20-6. Relative Amounts of Enzymes in Various Organs (Relative to Serum). In: Henry’s Clinical Diagnosis and Management by Laboratory Methods, 22nd ed. [MDConsult]
Shows that while ALT is present in kidney, spleen, heart, skeletal muscle, and even red cells, the concentration is highest in the liver. Compare to distribution of concentrations of AST.
Alanine aminotransferase (ALT), serum. In: Degowin’s Diagnostic Examination [AccessMedicine]
States that elevated ALT is a finding “usually” seen in liver injury, but that in “severe damage to skeletal muscle” it can be elevated. No quantification of the extent of skeletal damage required to cause this elevation.
Weibrecht K, et al. Liver Aminotransferases Are Elevated with Rhabdomyolysis in the Absence of Significant Liver Injury. J. Med. Toxicol. 2010; 6:294–300
Retrospective chart review of 215 cases of rhabdomyolysis with CPK of ≥1,000 U/L and reported AST and ALT values. Excluded patients with MI, chronic elevated liver enzymes, or known infections/conditions causing liver injury. RESULTS: 161 (75%) of patients had elevated ALT. 200 (93%) of patients had elevated AST. AST, but not ALT, levels correlated with CPK levels during hospital stay (see Fig. 1.)