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Introduction ⬇

The enzyme gamma (γ)-glutamyl transpeptidase (GGT) is present mainly in the liver, kidney, and pancreas. Despite the fact that the kidney has the highest level of this enzyme, the liver is considered the source of normal serum activity. GGT has no origin in bone or placenta.

This test is used to determine liver cell dysfunction and to detect alcohol-induced liver disease. Because the GGT test is very sensitive to the amount of alcohol consumed by chronic drinkers, 
it can be used to monitor the cessation or reduction of alcohol consumption in patients with 
chronic alcohol use disorder and early-risk drinkers. GT activity is elevated in all forms of liver disease.

This test is much more sensitive than either the ALP test or the transaminase test (i.e., SGOT, serum glutamic-pyruvic transaminase [SGPT]) in detecting obstructive jaundice, cholangitis, and cholecystitis. It is also indicated in the differential diagnosis of liver disease in children and pregnant women who have elevated levels of LDH and ALP. GGT is also useful as a marker for pancreatic cancer, prostatic cancer, and hepatic metastasis from breast and colon cancer.

Normal Findings ⬆ ⬇

Men: 7–47 U/L (0.12–1.80 μkat/L)

Women: 5–25 U/L (0.08–0.42 μkat/L)

Values are higher in newborns and in the first 3–6 months. Values vary with method (check with your laboratory).

Procedure ⬆ ⬇

  1. Obtain a 5-mL venous blood sample. Serum is used.

  2. Observe standard precautions. Label the specimen with the patient’s name, date and time of collection, and test(s) ordered. Place the specimen in a biohazard bag.

Clinical Implications ⬆ ⬇

  1. Increased GGT levels are associated with the following conditions:

    1. Liver diseases

      1. Hepatitis (acute and chronic)

      2. Cirrhosis (obstructive and familial)

      3. Liver metastasis and carcinoma

      4. Cholestasis (especially during or following pregnancy)

      5. Chronic alcoholic liver disease, alcoholism

      6. Infectious mononucleosis

    2. GGT levels are also increased with the following conditions:

      1. Pancreatitis

      2. Carcinoma of prostate and pancreas

      3. Carcinoma of breast and lung

      4. Systemic lupus erythematosus

      5. Glycogen storage disease

    3. With MI, GGT is usually normal. However, if there is an increase, it occurs about 4 days after MI and probably implies liver damage secondary to cardiac insufficiency.

    4. Hyperthyroidism

  2. Decreased GGT levels are found in hypothyroidism.

  3. GGT values are normal with bone disorders, bone growth, pregnancy, skeletal muscle disease, strenuous exercise, and renal failure. Children and adolescents are normal.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and blood-drawing procedure. No alcohol is allowed before the test.

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Have patient resume normal activities.

  2. Review test results; report and record findings. Modify the nursing care plan as needed. Monitor as appropriate for liver, pancreatic, or thyroid disease and cancer recurrence.

  3. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. Various drugs (e.g., phenothiazines, barbiturates) affect test outcomes (see Appendix E)

  2. Alcohol (ethanol)