Enzymes are specialized and very specific proteins, which catalyze various chemical reactions. Research work and application of clinical enzymology in medicine have been expanded rapidly, it plays an important role in diagnosis, prognosis and evaluation of different diseases and metabolic disorders (Bogin and Sommer, 1976). Most of the body enzymes are functioning intracellularly and are present in very low concentrations in serum. Each cell type has its own specific enzymes.

Blood levels of enzymes reflects the balance between the release of intracellular enzymes and their catabolism (Kerr, 2002). Elevated levels of serum enzymes reflect the destruction of the cell membrane and release of their enzyme contents. Hence serum enzymes are specific, they can be used for diagnosis of a variety of diseases. For example, GGT is specific for the liver. ALP is specific for the cholangitis and for abnormal conditions that arise in the bone or intestine. Serum AST is elevated in diseases affecting skeletal or myocardium muscles and liver. Serum CK is accompany necrosis or damage to skeletal or myocardial muscles.

Enzymes that are mostly measured in blood for diagnosis of different diseases, including creatine phosphokinase (CK), lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transferase (GGT), alkaline phosphatase (ALP). High levels of enzymes in blood indicate acute diseases. However, the enzyme levels are moderately or mildly increased in chronic diseases.