5'-Nucleotidase

5′-Nucleotidase (5NT) is an intrinsic membrane glycoprotein that is present as an enzyme in a wide variety of mammalian cells. ^[1] It facilitates the hydrolysis of the phosphate group from 5’-nucleotides, resulting in corresponding nucleosides.

Normal findings ^[2] :0-1.6 units at 37° C or 0-1.6 units at 37° C (SI units) 

5’-Nucleotidase (5NT) levels are elevated the following:

• Obstructive or cholestatic liver disease

• Hepatitis

• Intrinsic liver damage

• Primary liver malignancy and metastasis

• Biliary cirrhosis

• Use of hepatotoxic drugs

Specimen: Serum separation tube (SST)

Container: Vacutainer, red/black top (SST; see image below)

Collect 1 mL; minimum, 0.4 mL

Method: Routine venipuncture

Special instructions: Allow sample to clot completely at room temperature, then separate immediately

Related tests include serum alkaline phosphatase and gamma-glutamyltransferase (GGT).

Description

5′-Nucleotidase (5NT) is an intrinsic membrane glycoprotein that is present as an enzyme in a wide variety of mammalian cells. ^[1] It facilitates the hydrolysis of the phosphate group from 5’-nucleotides, resulting in corresponding nucleosides.

Indications/Applications

Despite its widespread distribution in the human body, serum elevations of 5NT are medically useful in identifying hepatobiliary disease.

The test can be used in conjunction with elevated alkaline phosphatase levels or other clinical findings suggestive of liver/gall bladder disease. It is especially useful (in the absence of pregnancy) when the differential diagnoses include hepatobiliary disease processes versus those of an osseous nature because it is not elevated in osteoblastic bone pathologies.

GGT can be used in a similar manner, but, generally, GGT levels are elevated in any hepatocellular injury, while 5NT is more specific to situations resulting in obstructive or cholestatic liver disease. Currently, laboratory testing for GGT is less cumbersome and more available than 5NT. ^{[3, 4, 5, 6, 7]}

The following are pathologic states in which 5NT is elevated:

• Obstructive or cholestatic liver disease ^[8]

• Hepatitis

• Intrinsic liver damage (elevated in acute alcohol use, chronic alcohol use, and cirrhosis)

• Malignancy (primary hepatic; metastasis [5NT is especially useful in monitoring/confirming])

• Biliary cirrhosis

Considerations

Nonpathologic conditions in which 5NT levels are elevated include the following:

• Pregnancy

• Use of hepatotoxic medications (eg, acetaminophen, halothane, isoniazid [INH], methyldopa, nitrofurantoin)