Alanine Aminotransferase (ALT) (GPT), Serum

CPT CODE:

USEFUL FOR:

ALT is useful in the diagnosis and monitoring of liver diseaseassociated with hepatic necrosis.

SPECIMEN REQUIRED:

Draw blood in a plain, red-top tube(s) or a serum gel tube(s). Spin down and send 0.5 mL of serum either refrigerated or frozen in plastic vial.Note:    Patient's age and sex are required on request form for              processing.

TRANSPORT TEMPERATURE:

Refrig\Frozen OK\Ambient NO

CLINICAL INFORMATION:

Alanine aminotransferase (ALT) is present primarily in liver cells. Inviral hepatitis and other forms of liver disease associated with hepaticnecrosis, serum ALT is elevated even before the clinical signs andsymptoms of the disease appear. Although serum levels of both ASTand ALT become elevated whenever disease processes affect livercell integrity, ALT is a more liver-specific enzyme. Serum elevationsof ALT are rarely observed in conditions other than parenchymal liverdisease. Moreover, the elevation of ALT activity persists longer thandoes AST activity.

CLINICAL INTERPRETATION:

Elevated ALT values are seen in parenchymal liver diseasescharacterized by a destruction of hepatocytes. Values aretypically at least ten times above the normal range. Levels mayreach values as high as one hundred times the upper referencelimit, although twenty to fifty-fold elevations are most frequentlyencountered. In infectious hepatitis and other inflammatory conditionsaffecting the liver, ALT is characteristically as high as or higher thanAST, and the ALT/AST ratio, which normally and in other conditionis less than 1, becomes greater than unity. ALT levels are usuallyelevated before clinical signs and symptoms of disease appear.

REFERENCE VALUES:

Males

      0-11 months:  not established

      > or = 1 year:  7-55 U/L

Females

      0-11 months:  not established

      > or = 1 year:  7-45 U/L