5 Nucleotidase (5′ NT)

5′-NT is an enzyme catalyzing the hydrolysis of nucleoside-5′-mono- phosphates to nucleosides and inorganic phosphate. The enzyme is widely distributed in human and animal tissues. The activity present in sera is released from membranes of liver cells by bile salts and has been used as a marker for liver disease. Healthy subjects have a 5′-NT activity in the range of 0-10 U/L. Increased enzyme levels in sera are associated with certain forms of liver disease, such as intra- or extra-hepatic obstruction and particularly in cases of hepatic carcinoma and in mastectomy patients with recurrent metastases. The diagnostic value of 5′-NT has been shown to be superior to other liver enzymes, especially in cases of liver metastasis.