Alpha-Fetoprotein (AFP) Test

1. Objective

The objective of the AFP test was to measure the level of alpha-fetoprotein in the blood to help detect certain liver diseases, cancers, and fetal abnormalities during pregnancy.

2. Principle

The principle was based on immunoassay methods. AFP in the serum bound to specific antibodies, and the antigen–antibody reaction was measured quantitatively using enzyme-linked immunosorbent assay (ELISA), chemiluminescence, or other immunoassay techniques.

3. Materials

Patient’s blood sample (serum)

Collection tubes and centrifuge

ELISA kit or automated immunoassay analyzer

Reagents: coated microplates, conjugated antibodies, substrate solution, stop solution

Micropipettes and tips

4. Procedure (ELISA method)

1. Blood sample was collected and centrifuged to obtain serum.

2. Serum was added to microplate wells coated with anti-AFP antibodies.

3. After incubation, wells were washed to remove unbound substances.

4. Enzyme-conjugated secondary antibody was added, binding to AFP.

5. Substrate solution was added, producing a color reaction proportional to AFP concentration.

6. Optical density was read using an ELISA reader, and AFP concentration was calculated from a standard curve.

5. Results 

Normal Ranges

Adults (non-pregnant): < 10 ng/mL

Pregnancy (2nd trimester): 10–150 ng/mL (varies by gestational age)

Abnormal results:

Elevated AFP in adults suggested liver cancer (hepatocellular carcinoma), germ cell tumors, or chronic liver disease (hepatitis, cirrhosis).

Elevated AFP in pregnancy suggested neural tube defects or abdominal wall defects in the fetus.

Low AFP in pregnancy was associated with Down syndrome or other chromosomal abnormalities.

6. Uses

To screen and monitor liver cancer.

To evaluate testicular or ovarian germ cell tumors.

To screen pregnant women for fetal abnormalities.

To monitor treatment response and recurrence in liver cancer patients.

7. Consultation

Abnormal AFP values required further clinical evaluation:

In adults: Imaging (ultrasound, CT, MRI) and liver function tests.

In pregnancy: Repeat AFP testing, detailed ultrasound, and possible amniocentesis.

Referral to an oncologist or gynecologist was recommended based on findings.