Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) are widely recognized as gold-standard markers for hepatocellular injury. However, their reliability is compromised in individuals with underlying muscle disorders, such as Duchenne Muscular Dystrophy (DMD), where elevated transaminase levels often reflect muscle damage rather than liver pathology. This complicates liver safety assessments in clinical trials targeting DMD. Serum glutamate dehydrogenase (GLDH), a liver-specific mitochondrial enzyme, has emerged as a promising alternative biomarker for hepatocellular damage in this context. Here, we share data supporting the use of GLDH as a liver safety biomarker in two DMD clinical trials: vamorolone (n=169, NCT02760264 and NCT02760277) and edasalonexent (n=131, NCT03703882). As expected in the DMD population, ALT (ULN <30 U/L) and AST (ULN <30 U/L) levels in enrolled subjects exceeded their ULN at baseline due to underlying muscle injury, whereas GLDH levels were within its reference range (ULN <10 U/L). Because ALT and AST are chronically elevated in DMD, changes in these markers were assessed as fold-change over each participant’s baseline level, while GLDH and gamma-glutamyltransferase (GGT) were evaluated relative to their ULN. In the vamorolone trials, a single participant exhibited a GLDH elevation to 5× ULN (50.5 U/L) at 18 weeks of treatment, accompanied by a 1.3-fold elevation in GGT (29 U/L, ULN <22 U/L). In contrast, ALT and AST exhibited only 2–3-fold elevations over their individual subject baseline levels. In the edasalonexent trial, no patient exceeded a GLDH value of 13 U/L (ULN <10 U/L), and no other evidence of hepatotoxicity was identified. Overall, these observations provide additional evidence that GLDH is a sensitive and specific biomarker of liver injury that can be effectively used in subjects with high baseline transaminase activity due to muscle damage, including individuals living with DMD. Importantly, GLDH was recently qualified by the US Food and Drug Administration (FDA) as a biomarker to enhance liver safety monitoring in clinical trials (November 2025), further confirming its clinical utility in this setting.