Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (684 page)

   False-positive elevations can occur with tumors of the GI tract or with liver damage (e.g., cirrhosis, hepatitis, or drug or alcohol abuse) and pregnancy.

   Failure of the AFP value to return to normal by approximately 1 month after surgery suggests the presence of residual tumor.

   Elevation of AFP after remission suggests tumor recurrence; however, tumors originally producing AFP may recur without an increase in AFP.

   Fucosylated form of serum AFP that is most closely associated with HCC is recognized by a lectin from the common lentil (AFP-L3). AFP-L3 is most useful in the differential diagnosis of individuals with total serum AFP ≤200 ng/mL.

Suggested Reading

Trevisani F, D’Intino PE, Morselli-Labate AM, et al. Serum alpha-fetoprotein for diagnosis of hepatocellular carcinoma in patients with chronic liver disease: influence of HBsAg and anti-HCV status.
J Hepatol.
2001;34(4):570–575.

AMINOTRANSFERASES (AST, ALT)

   Definition

   Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT) are members of the transaminase family of enzymes, widely distributed in cells throughout the body. AST is primarily found in the heart, liver, skeletal muscle, and kidney, whereas ALT is found primarily in the liver and kidney, with lesser amounts in the heart and skeletal muscle. AST and ALT activities in the liver are about 7,000 and 3,000 times serum activities, respectively.

   
Normal range:

   AST:

   Less than or equal to 1 year: 30–80 U/L

   Greater than 1 year: 10–40 U/L

   ALT:

   Less than or equal to 1 year: 5–50 U/L

   Greater than 1 year: 10–40 U/L