Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (682 page)

   Limitations

   Phenotypic studies are recommended to confirm a suspected hereditary deficiency.

   False-positive results can occur if rheumatoid factor present.

α-FETOPROTEIN (AFP) TUMOR MARKER, SERUM

   Definition

   AFP is a glycoprotein that is normally produced during gestation by the fetal liver and yolk sac, the serum concentration of which is often elevated in patients with hepatocellular carcinoma (HCC). It is also found in some patients with cancer of the testes and ovaries.

   
Normal range:
0.6–6.60 ng/mL.

   Use

   Marker for hepatocellular and germ cell (nonseminoma) carcinoma.

   Follow-up management of patients undergoing cancer therapy, especially for testicular and ovarian tumors and for hepatocellular carcinoma. The measurement of AFP in serum, in conjunction with serum human chorionic gonadotropin, is an established regimen for monitoring patients with nonseminomatous testicular cancer. In addition, monitoring the rate of AFP clearance from serum after treatment is an indicator of the effectiveness of therapy. Conversely, the growth rate of progressive cancer can be monitored by serially measuring serum AFP concentration over time.

   Serial serum AFP testing is a useful adjunctive test for managing nonseminomatous testicular cancer.

   Interpretation

   
AFP is increased in the following disorders:

   Ataxia telangiectasia