gamma-Glutamyltranspeptidase

γ-Glutamyltranspeptidase

Synonym/acronym: Serum γ-glutamyltransferase, γ-glutamyl transpeptidase, GGT, SGGT.

Common use

To assist in diagnosing and monitoring liver disease.

Specimen

Serum (1 mL) collected in a gold-, red-, or red/gray-top tube. Plasma (1 mL) collected in a green-top (heparin) tube is also acceptable.

Normal findings

(Method: Enzymatic spectrophotometry)
AgeConventional & SI Units
Newborn–6 mo12–122 units/L
7 mo and older
 Male0–30 units/L
 Female0–24 units/L
Values may be elevated in older adults due to the effects of medications and the presence of multiple chronic or acute diseases with or without muted symptoms.

Description

Glutamyltransferase (GGT) assists with the reabsorption of amino acids and peptides from the glomerular filtrate and intestinal lumen. Hepatobiliary, renal tubular, and pancreatic tissues contain large amounts of GGT. Other sources include the prostate gland, brain, and heart. GGT is elevated in all types of liver disease and is more responsive to biliary obstruction, cholangitis, or cholecystitis than any of the other enzymes used as markers for liver disease.

This procedure is contraindicated for

    N/A

Indications

  • Assist in the diagnosis of obstructive jaundice in neonates
  • Detect the presence of liver disease
  • Evaluate and monitor patients with known or suspected alcohol abuse (levels rise after ingestion of small amounts of alcohol)

Potential diagnosis

Increased in

  • GGT is released from any damaged cell in which it is stored, so conditions that affect the liver, kidneys, or pancreas and cause cellular destruction demonstrate elevated GGT levels.

  • Cirrhosis
  • Diabetes with hypertension
  • Hepatitis
  • Hepatobiliary tract disorders
  • Hepatocellular carcinoma
  • Hyperthyroidism (there is a strong association with concurrent liver abnormalities)
  • Infectious mononucleosis
  • Obstructive liver disease
  • Pancreatitis
  • Renal transplantation
  • Significant alcohol ingestion

Decreased in

    Hypothyroidism (related to decreased enzyme production by the liver)

Critical findings

    N/A

Interfering factors

  • Drugs and substances that may increase GGT levels include acetaminophen, alcohol, aminoglutethimide, anticonvulsants, aurothioglucose, barbiturates, captopril, cetirizine, dactinomycin, dantrolene, dexfenfluramine, estrogens, flucytosine, halothane, labetalol, medroxyprogesterone, meropenem, methyldopa, naproxen, niacin, nortriptyline, oral contraceptives, pegaspargase, phenothiazines, piroxicam, probenecid, rifampin, streptokinase, tocainide, and trifluoperazine.
  • Drugs that may decrease GGT levels include clofibrate conjugated estrogens and ursodiol.

Nursing Implications and Procedure

Potential nursing problems

ProblemSigns & SymptomsInterventions
Fatigue (Related to hepatic disease process; malnutrition; anemia; chemotherapy; radiation therapy)Decreased concentration; increased physical complaints; inability to restore energy with sleep; reports being tired; inability to maintain normal routineAssess for physical cause of fatigue; pace activities to preserve energy stores; rate fatigue on a numeric scale to trend degree of fatigue over time; identify what aggravates and decreases fatigue; assess for related emotional factors such as depression; evaluate current medications in relation to fatigue; assess for physiologic factors such as anemia
Confusion (Related to an alteration in fluid and electrolytes, hepatic disease and encephalopathy; acute alcohol consumption; hepatic metabolic insufficiency)Disorganized thinking, restless, irritable, altered concentration and attention span, changeable mental function over the day, hallucinations; altered attention span; inablity to follow directions; disoriented to person, place, time, and purpose; inappropriate affectTreat the medical condition; correlate confusion with the need to reverse altered electrolytes; evaluate medications; prevent falls and injury through appropriate use of postural support, bed alarm, or restraints; consider pharmacological interventions; record accurate intake and output to assess fluid status; monitor blood ammonia level; determine last alcohol use; assess for symptoms of hepatic encephalopathy such as confusion, sleep disturbances, incoherence; protect the patient from physical harm; administer lactulose as prescribed
Fluid volume (Related to vomiting; decreased intake; compromised renal function; overly aggressive fluid resuscitation; overly aggressive diuresis)Overload: edema, shortness of breath, increased weight, ascites, rales, rhonchi, and diluted laboratory values. Deficient: decreased urinary output, fatigue, and sunken eyes, dark urine, decreased blood pressure, increased heart rate, and altered mental statusRecord daily weight and monitor trends; record accurate intake and output; collaborate with physician with administration of IV fluids to support hydration; monitor laboratory values that reflect alterations in fluid status (potassium, blood urea nitrogen, creatinine, calcium, hemoglobin, and hematocrit); manage underlying cause of fluid alteration; monitor urine characteristics and respiratory status; establish baseline assessment data; collaborate with physician to adjust oral and IV fluids to provide optimal hydration status; administer replacement electrolytes as ordered
Skin (Related to jaundice and elevated bilirubin levels; excessive scratching)Jaundiced skin and sclera; dry skin; itching skin; damage to skin associated with scratchingApply lotion to keep the skin moisturized; avoid alkaline soaps; discourage scratching; apply mittens if patient is not able to follow direction to avoid scratching; administer antihistamines as ordered

Pretest

  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this test can assist in assessing liver function.
  • Obtain a history of the patient’s complaints, including a list of known allergens, especially allergies or sensitivities to latex.
  • Obtain a history of the patient’s hepatobiliary system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a history of IV drug use, alcohol use, high-risk sexual activity, and occupational exposure.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Inform the patient that specimen collection takes approximately 5 to 10 min. Address concerns about pain and explain that there may be some discomfort during the venipuncture.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Note that there are no food, fluid, or medication restrictions unless by medical direction.

Intratest

  • Potential complications: N/A
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Instruct the patient to cooperate fully and to follow directions. Direct the patient to breathe normally and to avoid unnecessary movement.
  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient, and label the appropriate specimen container with the corresponding patient demographics, initials of the person collecting the specimen, date, and time of collection. Perform a venipuncture.
  • Remove the needle and apply direct pressure with dry gauze to stop bleeding. Observe/assess venipuncture site for bleeding or hematoma formation and secure gauze with adhesive bandage.
  • Promptly transport the specimen to the laboratory for processing and analysis.

Post-Test

  • Inform the patient that a report of the results will be sent to the requesting health-care provider (HCP), who will discuss the results with the patient.
  • Nutritional Considerations: Increased GGT levels may be associated with liver disease. Dietary recommendations may be indicated and vary depending on the condition and its severity. Currently, there are no specific medications that can be given to cure hepatitis, but elimination of alcohol ingestion and a diet optimized for convalescence are commonly included in the treatment plan. A high-calorie, high-protein, moderate-fat diet with a high fluid intake is often recommended for patients with hepatitis. Treatment of cirrhosis is different because a low-protein diet may be in order if the patient’s liver has lost the ability to process the end products of protein metabolism. A diet of soft foods also may be required if esophageal varices have developed. Ammonia levels may be used to determine whether protein should be added to or reduced from the diet. The patient should be encouraged to eat simple carbohydrates and emulsified fats (as in homogenized milk or eggs) rather than complex carbohydrates (e.g., starch, fiber, and glycogen [animal carbohydrates]) and complex fats, which require additional bile to emulsify them so that they can be used. The cirrhotic patient should also be carefully observed for the development of ascites, in which case fluid and electrolyte balance requires strict attention. The alcoholic patient should be encouraged to avoid alcohol and to seek appropriate counseling for substance abuse.
  • Recognize anxiety related to test results, and be supportive of impaired activity related to lack of neuromuscular control, perceived loss of independence, and fear of shortened life expectancy.
  • Depending on the results of this procedure, additional testing may be performed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.
  • Patient Education

    • Educate the patient regarding access to counseling services.
    • Provide teaching and information regarding the clinical implications of the test results, as appropriate.
    • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP.
    • Answer any questions or address any concerns voiced by the patient or family.
    • Discuss the implications of abnormal test results on the patient’s lifestyle.
    • Explain to the patient that ongoing fatigue can impact his or her ability to meet personal role performance expectations.
    • Explain that both physical and emotional factors can contribute to fatigue.
  • Expected Patient Outcomes

    • Knowledge
    • Validates understanding that chronic fatigue that goes untreated can decrease quality of life
    • Identifies how adequate nutrition may assist to decrease fatigue
    • Skills
    • Independently reviews his or her current list of medications to evaluate if any prescription or nonprescription medications are contributing to fatigue
    • Accurately develops a list of actions that can be taken to reduce fatigue and promote positive health
    • Attitude
    • Complies with the recommendation to obtain a sleep-disorder evaluation to assess for other causes of fatigue
    • Recognizes that both excess and inadequate exercise can contribute to fatigue and makes an effort to pace physical energy expenditures appropriately

Related Monographs

  • Related tests include ALT, ALP ammonia, AST, bilirubin, cholangiography percutaneous transhepatic, electrolytes, HAV antibody, HBV antigen and antibody, HCV antibody, hepatobiliary scan, infectious mono screen, KUB studies, liver and spleen scan, MRI liver, TSH, US abdomen, and US liver.
  • Refer to the Hepatobiliary System table at the end of the book for related tests by body system.
References in periodicals archive ?
LIVER FUNCTION TEST RESULTS Parameter (normal range) Dec 07 Jan 08 Feb 08 June 08 TBil (0-17) 3 6 87 17 ALT (0-40) 111 80 122 40 AST (0-40) 126 60 268 48 ALP (40-120) 277 190 332 100 GGT (0-35) 295 196 507 96 TBil = total bilirubin ([micro]mol/l); ALT = alanine transaminase (IU/l); AST = aspartate transaminase (IU/l); ALP = alkaline phosphatase (IU/l); GGT = gamma-glutamyltranspeptidase (IU/l).
Two proteins that serve as markers of classical liver tumors -- gamma-glutamyltranspeptidase and glutathione S-transferase-P--are conspicuously absent in PPC-induced tumors.
Accumulation of DNA damage in the organs of mice deficient in gamma-glutamyltranspeptidase.
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