Which enzyme level is primarily measured to assess hepatocellular injury in patients suspected of liver damage or viral hepatitis?

The enzyme primarily measured to assess hepatocellular injury in patients suspected of liver damage or viral hepatitis is Alanine Aminotransferase (ALT).

- ALT is an enzyme found predominantly in the cytosol of hepatocytes, making it a highly specific marker for liver cell injury.
- When liver cells are damaged, ALT is released into the bloodstream, leading to elevated serum levels.

- While Aspartate Aminotransferase (AST) is also elevated in liver injury, it is less specific because it is found in other tissues such as the heart, muscle, and kidneys.

- Alkaline Phosphatase (ALP) and Gamma-glutamyl Transferase (GGT) are enzymes more indicative of cholestasis or biliary tract disease, rather than primary hepatocellular damage.
- ALP rises in conditions involving bile duct obstruction, and GGT is often elevated with alcohol-related liver disease and biliary pathology.

Therefore, ALT is the most reliable enzyme for detecting and monitoring hepatocellular injury, including viral hepatitis and other causes of liver cell damage.

Reference: Harrison’s Principles of Internal Medicine, 20th Edition, Volume 2, Chapter 304/ Page 2799