Serum glutamic-oxaloacetic transaminase

serum

[se´rum] (pl. serums, se´ra) (L.) the clear portion of any animal or plant fluid that remains after the solid elements have been separated out. The term usually refers to blood serum, the clear, straw-colored, liquid portion of the plasma that does not contain fibrinogen or blood cells, and remains fluid after clotting of blood. Blood serum from persons or animals whose bodies have built up antibodies is called antiserum or immune serum. Inoculation with such an antiserum provides temporary, or passive, immunity against the disease, and is used when a person has already been exposed to or has contracted the disease. Diseases in which passive immunization is sometimes used include diphtheria, tetanus, botulism, and gas gangrene.antilymphocyte serum (ALS) antiserum derived from animals that have been immunized against human lymphocytes, a powerful nonspecific immunosuppressive agent that causes destruction of circulating lymphocytes.antirabies serum antiserum obtained from the blood serum or plasma of animals immunized with vaccine" >rabies vaccine; used for postexposure prophylaxis against rabies if globulin" >rabies immune globulin is unavailable.blood grouping s's preparations containing particular antibodies against red cell antigens, used for blood typing. Those most commonly used are the anti-A and anti-B blood grouping serums used to determine ABO blood types and the anti-Rh blood grouping serums (anti-D, anti-C, anti-E, anti-c, and anti-e) used to determine Rh blood types.serum glutamic-oxaloacetic transaminase (SGOT) see aspartate transaminase.serum glutamic-pyruvic transaminase (SGPT) see alanine transaminase.immune serum antiserum.pooled serum the mixed serum from a number of individuals.serum sickness a hypersensitivity reaction following the administration of foreign serum or other antigens; it is marked by urticarial rashes, edema, adenitis, joint pains, high fever, and prostration. Reactions to antitoxin" >tetanus antitoxin derived from horse serum were especially common but are now rare owing to refinement of the antigenic components.serum sickness syndrome a serum sickness–like hypersensitivity reaction occurring after the administration of certain drugs. It is marked clinically by low-grade fever, urticaria, facial edema, pain and swelling of the joints, and lymphadenopathy, and occasionally may be associated with neuritis of the brachial plexus, guillain-barré syndrome, periarteritis nodosa, and nephritis.

as·par·tate a·mi·no·trans·fer·ase

(AST) (as-pahr'tāt ă-mē'nō-trans'fĕr-ās) An enzyme catalyzing the reversible transfer of an amine group from l-glutamic acid to oxaloacetic acid, forming α-ketoglutaric acid and l-aspartic acid; a diagnostic aid in viral hepatitis and in myocardial infarction.
Synonym(s): glutamic-oxaloacetic transaminase, serum glutamic-oxaloacetic transaminase.

Aspartate Aminotransferase

Synonym/acronym: Serum glutamic-oxaloacetic transaminase, AST, SGOT.

Common use

Considered an indicator of cellular damage in liver disease, such as hepatitis or cirrhosis; and in heart disease, such as myocardial infarction.

Specimen

Serum (1 mL) collected in a gold-, red-, or red/gray-top tube.

Normal findings

(Method: Spectrophotometry, enzymatic at 37°C)

Age	Conventional Units	SI Units (Conventional Units × 0.017)
Newborn	25–75 units/L	0.43–1.28 micro kat/L
10 days–23 mo	15–60 units/L	0.26–1.02 micro kat/L
2–3 yr	10–56 units/L	0.17–0.95 micro kat/L
4–6 yr	20–39 units/L	0.34–0.66 micro kat/L
7–19 yr	12–32 units/L	0.2–0.54 micro kat/L
20–49 yr
Male	20–40 units/L	0.34–0.68 micro kat/L
Female	15–30 units/L	0.26–0.51 micro kat/L
Greater than 50 yr (older adult)
Male	10–35 units/L	0.17–0.6 micro kat/L
Greater than 45 yr (older adult)
Female	10–35 units/L	0.17–0.6 micro kat/L

Values may be slightly 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

Aspartate aminotransferase (AST) is an enzyme that catalyzes the reversible transfer of an amino group between aspartate and α-ketoglutaric acid in the citric acid or Krebs cycle, a powerful and essential biochemical pathway for releasing stored energy. It was formerly known as serum glutamic-oxaloacetic transaminase (SGOT). AST exists in large amounts in liver and myocardial cells and in smaller but significant amounts in skeletal muscle, kidneys, pancreas, red blood cells, and the brain. Serum AST rises when there is damage to the tissues and cells where the enzyme is found and levels directly reflect the extent of damage. AST values greater than 500 units/L are usually associated with hepatitis and other hepatocellular diseases in an acute phase. AST levels are very elevated at birth, decrease with age to adulthood, and increase slightly in elderly adults. Note: Measurement of AST in evaluation of myocardial infarction has been replaced by more sensitive tests, such as creatine kinase–MB fraction (CK-MB) and troponin.

This procedure is contraindicated for

N/A

Indications

Assist in the diagnosis of disorders or injuries involving the tissues where AST is normally found
Assist (formerly) in the diagnosis of myocardial infarction (Note: AST rises within 6 to 8 hr, peaks at 24 to 48 hr, and declines to normal within 72 to 96 hr of a myocardial infarction if no further cardiac damage occurs)
Compare serially with alanine aminotransferase levels to track the course of hepatitis
Monitor response to therapy with potentially hepatotoxic or nephrotoxic drugs
Monitor response to treatment for various disorders in which AST may be elevated, with tissue repair indicated by declining levels

Potential diagnosis

Increased in

AST is released from any damaged cell in which it is stored, so conditions that affect the liver, kidneys, heart, pancreas, red blood cells, or skeletal muscle, and cause cellular destruction demonstrate elevated AST levels.

Significantly Increased in (greater than five times normal levels)

Acute hepatitis (AST is very elevated in acute viral hepatitis)
Acute hepatocellular disease (especially related to chemical toxicity or drug overdose; moderate doses of acetaminophen have initiated severe hepatocellular disease in alcoholics)
Acute pancreatitis
Shock

Moderately Increased in (three to five times normal levels)

Alcohol abuse (chronic)
Biliary tract obstruction
Cardiac arrhythmias
Cardiac catheterization, angioplasty, or surgery
Cirrhosis
Chronic hepatitis
Congestive heart failure
Infectious mononucleosis
Liver tumors
Muscle diseases (e.g., dermatomyositis, dystrophy, gangrene, polymyositis, trichinosis)
Myocardial infarct
Reye’s syndrome
Trauma (related to injury or surgery of liver, head, and other sites where AST is found)

Slightly Increased in (two to three times normal)

Cerebrovascular accident
Cirrhosis, fatty liver (related to obesity, diabetes, jejunoileal bypass, administration of total parenteral nutrition)
Delirium tremens
Hemolytic anemia
Pericarditis
Pulmonary infarction

Decreased in

(presumed to be related to a corresponding deficiency of vitamin B₆ observed in hemodialysis patients)

(related to a buildup of toxins which modify the activity of coenzymes required for transaminase activity)

₆

(related to the lack of vitamin B₆, a required cofactor for the transaminases)

Critical findings

N/A

Interfering factors

Drugs that may increase AST levels by causing cholestasis include amitriptyline, anabolic steroids, androgens, benzodiazepines, chlorothiazide, chlorpropamide, dapsone, erythromycin, estrogens, ethionamide, gold salts, imipramine, mercaptopurine, nitrofurans, oral contraceptives, penicillins, phenothiazines, progesterone, propoxyphene, sulfonamides, tamoxifen, and tolbutamide.
Drugs that may increase AST levels by causing hepatocellular damage include acetaminophen, acetylsalicylic acid, allopurinol, amiodarone, anabolic steroids, anticonvulsants, asparaginase, azithromycin, bromocriptine, captopril, cephalosporins, chloramphenicol, clindamycin, clofibrate, danazol, enflurane, ethambutol, ethionamide, fenofibrate, fluconazole, fluoroquinolones, foscarnet, gentamicin, indomethacin, interferon, interleukin-2, levamisole, levodopa, lincomycin, low-molecular-weight heparin, methyldopa, monoamine oxidase inhibitors, naproxen, nifedipine, nitrofurans, oral contraceptives, probenecid, procainamide, quinine, ranitidine, retinol, ritodrine, sulfonylureas, tetracyclines, tobramycin, and verapamil.
Drugs that may decrease AST levels include allopurinol, cyclosporine, interferon alpha, naltrexone, progesterone, trifluoperazine, and ursodiol.
Hemolysis falsely increases AST values.
Hemodialysis falsely decreases AST values.

Nursing Implications and Procedure

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 cardiovascular and hepatobiliary systems, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
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 to the patient 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 made available to the requesting health-care provider (HCP), who will discuss the results with the patient.
Nutritional Considerations: Increased AST levels may be associated with liver disease. Dietary recommendations may be indicated and will 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; a low-protein diet may be in order if the patient’s liver can no longer process the end products of protein metabolism. A diet of soft foods 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. Patients 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 be observed carefully for the development of ascites, in which case fluid and electrolyte balance requires strict attention.
Nutritional Considerations: Increased AST levels may be associated with coronary artery disease (CAD). Nutritional therapy is recommended for the patient identified to be at risk for developing CAD or for individuals who have specific risk factors and/or existing medical conditions (e.g., elevated LDL cholesterol levels, other lipid disorders, insulin-dependent diabetes, insulin resistance, or metabolic syndrome). Other changeable risk factors warranting patient education include strategies to encourage patients, especially those who are overweight and with high blood pressure, to safely decrease sodium intake, achieve a normal weight, ensure regular participation in moderate aerobic physical activity three to four times per week, eliminate tobacco use, and adhere to a heart-healthy diet. If triglycerides also are elevated, the patient should be advised to eliminate or reduce alcohol. The 2013 Guideline on Lifestyle Management to Reduce Cardiovascular Risk published by the ACC and AHA in conjunction with the NHLBI recommends a “Mediterranean”-style diet rather than a low-fat diet. The new guideline emphasizes inclusion of vegetables, whole grains, fruits, low-fat dairy, nuts, legumes, and nontropical vegetable oils (e.g., olive, canola, peanut, sunflower, flaxseed) along with fish and lean poultry. A similar dietary pattern known as the DASH diet makes additional recommendations for the reduction of dietary sodium. Both dietary styles emphasize a reduction in consumption of red meats, which are high in saturated fats and cholesterol, and other foods containing sugar, saturated fats, trans fats, and sodium.
Social and Cultural Considerations: Numerous studies point to the prevalence of excess body weight in American children and adolescents. Experts estimate that obesity is present in 25% of the population ages 6 to 11. The medical, social, and emotional consequences of excess body weight are significant. Special attention should be given to instructing the child and caregiver regarding health risks and weight-control education.
Recognize anxiety related to test results, and be supportive of fear of shortened life expectancy. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate. Educate the patient regarding access to counseling services. Provide contact information, if desired, for the American Heart Association (www.americanheart.org) or the NHLBI (www.nhlbi.nih.gov).
Instruct the patient to immediately report chest pain and changes in breathing pattern to the HCP.
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.
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.

Related Monographs

Related tests include acetaminophen, ALT, albumin, ALP, ammonia, AMA/ASMA, α₁-antitrypsin/phenotyping, bilirubin and fractions, biopsy liver, cholangiography percutaneous transhepatic, cholangiography post-op, CT biliary tract and liver, ERCP, ethanol, ferritin, GGT, hepatitis antigens and antibodies, hepatobiliary scan, iron/total iron-binding capacity, liver and spleen scan, protein and fractions, PT/INR, US abdomen, and US liver if liver disease is suspected; and antiarrhythmic drugs, apolipoprotein A and B, ANP, BNP, blood gases, CRP, calcium/ionized calcium, CT scoring, cholesterol (total, HDL, and LDL), CK, echocardiography, Holter monitor, homocysteine, LDH, MRI chest, myocardial infarct scan, myocardial perfusion heart scan, myoglobin, PET heart, potassium, triglycerides, and troponin if myocardial infarction is suspected.
See the Cardiovascular and Hepatobiliary systems tables at the end of the book for related tests by body system.