Alanine Aminotransferase (ALT, Serum Glutamic-Pyruvic Transaminase [SGPT])

Test Description

Alanine aminotransferase (ALT) is an enzyme found in the kidneys, heart, and skeletal

muscle tissue but primarily in liver tissue. It functions as a catalyst in the reaction

needed for amino acid production. The test is used mainly in the diagnosis of

liver disease and to monitor the effects of hepatotoxic drugs.

ALT is assessed along with asparate aminotransferase (AST) in monitoring liver

damage. These two values normally exist in an approximately 1:1 ratio. The AST is

greater than the ALT in alcohol-induced hepatitis, cirrhosis, and metastatic cancer

of the liver. ALT is greater than AST in the case of viral or drug-induced hepatitis

and hepatic obstruction due to causes other than malignancy.

The degree of increase in these enzyme levels provides information as to the

possible source of the problem. A twofold increase is suggestive of an obstructive

problem, often requiring surgical intervention. A 10-fold increase of ALT and AST

indicates a probable medical problem such as hepatitis.

THE EVIDENCE FOR PRACTICE

In managing abnormal lipids, statin medications are commonly used. One major side effect

of statin use is liver toxicity, although the likelihood of liver transaminase elevations

>3 times the upper limit of normal is small. Liver transaminases (ALT and AST) are

obtained 6 to 12 weeks after statin therapy is initiated.

Normal Values

Female: 7–30 U/L (0.12–0.50 μkat/L SI units)

Male: 10–55 U/L (0.17–0.91 μkat/L SI units)

Possible Meanings of Abnormal Values

Increased                                                                                                                                              

Biliary obstruction

Bone metastases

Cholestasis

Cirrhosis

Congestive heart failure

Eclampsia

Hepatic ischemia

Hepatic necrosis

Hepatitis

Infectious mononucleosis

Liver cancer

Muscle inflammation

Obesity

Pancreatitis

Pulmonary infarction

Reye’s syndrome

Shock

Trauma

Contributing Factors to Abnormal Values

• Hemolysis of the blood sample may alter test results.

• Drugs that may increase ALT levels are numerous and include: ACE-inhibitors,

acetaminophen, anticonvulsants, antibiotics, antipsychotics, benzodiazepines, estrogens,

ferrous sulfate, heparin, interferons, lipid-lowering agents, NSAIDs, salicylates,

thiazides.

Interventions/Implications

Pretest

• Explain to the patient the purpose of the test and the need for a blood sample to be drawn.

• No fasting is required before the test. 

Procedure

• A 7-mL blood sample is drawn in a collection tube containing a silicone gel.

• Gloves are worn throughout the procedure.

Posttest

• Apply pressure for 3 to 5 minutes at venipuncture site. Apply dressing, periodically

   assessing for continued bleeding.

• Teach the patient to monitor the site. If the site begins to bleed, the patient should apply

   direct pressure and, if unable to control the bleeding, return to the laboratory or notify

   the primary care provider.

• Label the specimen and transport it to the laboratory.

• Report abnormal findings to the primary care provider.

 Clinical Alerts                                                                                                                                   

• With liver dysfunction, the patient may have prolonged clotting time.

• Liver enzymes, including ALT and AST, are routinely monitored in patients who

   take HMG-CoEnzyme A reductase inhibitors (“statin” medications).