Which laboratory value is most relevant to monitor in a patient receiving dantrolene?

• A. ALT
• B. LDH
• C. AST
• D. Alkaline phosphatase

Answer: (B)

When dantrolene is used, the main concern is stopping the dangerous muscle overactivity and the resulting muscle breakdown from malignant hyperthermia. Muscle cell injury releases enzymes and other proteins into the blood, and LDH (lactate dehydrogenase) is a sensitive marker of that tissue breakdown. In this setting, LDH helps gauge how much muscle damage is occurring and whether the treatment is effectively limiting that damage.

Liver enzymes like ALT and AST, and alkaline phosphatase, reflect liver function and potential hepatotoxicity from drugs, including dantrolene, but they don’t track the acute extent of muscle injury or the immediate response to therapy as LDH does.