PMLS Medical Technology Education Practice Exam

Alanine aminotransferase (ALT) is the enzyme most specific for hepatocellular injury because it is highly concentrated in liver cells and elevations mainly reflect damage to hepatocytes. AST is also present in the liver but exists in many other tissues such as muscle, heart, and kidneys, so it is less specific for liver cell injury. ALP and GGT are more indicative of cholestasis or biliary injury; ALP is also found in bone, and GGT can be elevated with various liver conditions and alcohol use, making them less specific for hepatocyte damage. In hepatocellular injury, ALT tends to rise prominently, providing a clearer signal of liver cell damage, whereas AST can be influenced by other tissues. If the pattern shows AST disproportionately higher than ALT (AST/ALT ratio > 2), that can suggest alcoholic liver disease, but ALT remains the more liver-specific marker for hepatocellular injury.