Significance of hepatic enzymes: A review

Abstract

The assay of serum enzymes is very useful for the differential diagnosis and monitoring of various hepatobiliary disorders. Aspartate aminotransferases are found in the liver, cardiac muscle, skeletal muscle, kidneys, brain, pancreas, lungs, leukocytes, and erythrocytes in decreasing order of concentration. Alanine aminotransferases are found in the liver, muscle (cardiac and skeletal), kidneys, and erythrocytes and these are specific indicators of hepatocellular injury in dogs and cats not in large animals and pigs due to low activity in liver tissue. Alkaline phosphatases are markers of cholestasis, present in most tissues but are in particularly high concentration in the osteoblasts of bone and the cells of the hepatobiliary tract, intestinal wall, renal tubules, and placenta. Gamma-glutamyl transferase occurs mainly in the cells of the liver, kidneys, pancreas, and prostate. Alcoholism and hepatocellular damage due to infectious hepatitis are causes of elevated plasma GGT activity. Sorbitol dehydrogenase is predominantly found in the liver and kidney and measurement of serum SDH activity has been shown to be valuable in assessing hepatocellular injury in various domestic species. Elevated serum arginase levels have been observed in naturally occurring liver diseases of horses, cattle, sheep, goats, and dogs. Ornithine carbamoyltransferase (OCT) is primarily found in the liver and is regarded as a liver-specific enzyme for detecting hepatocellular necrosis in domestic species. This review aims to highlight the importance of hepatic enzymes for diagnosis purposes.