Which statement best explains why ALT is more liver-specific than AST?

• A. ALT and AST are equally distributed across all tissues.
• B. ALT is mainly found in the liver, while AST is present in liver, heart, and muscle.
• C. AST is more liver-specific than ALT.
• D. ALT is produced primarily by the kidney.

Answer: (B)

ALT is more liver-specific because it is concentrated mainly in liver cells, so a rise in ALT in the blood more directly points to liver injury. In contrast, AST is found in several tissues outside the liver—such as heart and skeletal muscle—so elevations can come from damage to those tissues as well. That’s why the statement that ALT is mainly found in the liver, while AST is present in liver, heart, and muscle best explains ALT’s liver specificity. The other options don’t fit: ALT and AST aren’t equally distributed across all tissues; AST isn’t more liver-specific than ALT; and ALT isn’t produced primarily by the kidney.