Beware the Muscle: Silent Exercise-Induced Aminotransferase Elevation as a Diagnostic Pitfall in Hepatology and Pretreatment Screening-A Report of Two Cases.

Background: In clinical hepatology practice, pretreatment liver enzyme screening plays a key role in making management decisions, such as initiation of antituberculosis therapy or surveillance of chronic hepatitis B. Unrecognized extrahepatic sources of aminotransferase elevations can lead to misdiagnosis, inappropriate treatment alteration, and unnecessary invasive or costly investigations. Case presentation We present two cases of active young males who were undergoing liver biochemical testing for therapeutic decision-making for other underlying illnesses. Patient one was undergoing baseline liver enzyme testing prior to first-line antituberculosis treatment initiation while patient two was undergoing surveillance for e-antigen-negative hepatitis B infection. Both patients had asymptomatic aminotransferase elevations mimicking acute hepatocellular injury. There was a marked and disproportionate elevation of aspartate aminotransferase (AST) relative to alanine aminotransferase (ALT), in the setting of otherwise normal cholestatic and synthetic parameters. Targeted history revealed heavy resistance weight training prior to testing. Measurement of serum creatine kinase (CK) confirmed exercise-induced muscle injury, demonstrating elevated CK concentrations that paralleled the AST trajectory. Cessation of strenuous training led to rapid normalization of aminotransferases and a decline in CK levels, without interruption of tuberculosis management or unwarranted antiviral initiation.

Conclusion: Clinically silent exertional muscle injury is an underappreciated mimicker of acute liver injury. In patients presenting with isolated or disproportionate AST elevation, confirming a myogenic enzyme source via CK quantification can prevent misdiagnosis, eliminate unnecessary liver-directed workup, and avoid inappropriate modification or initiation of essential pharmacotherapy.