Alpha Foeto Protein (AFP)

Overview

Alpha Foeto Protein (AFP) is a protein produced mainly by the fetal liver and yolk sac during pregnancy, as shown in the introduction of the document (page 2). In babies, AFP levels are naturally high and gradually decrease after birth. By adulthood, AFP becomes undetectable in healthy individuals and has no physiological role in adults.

AFP is widely used as a diagnostic and monitoring marker. It helps assess:

1. Fetal abnormalities such as neural tube defects, Down syndrome, and Edwards syndrome (page 3).
2. Liver disorders, including cirrhosis and chronic hepatitis (page 3).
3. Cancers such as hepatocellular carcinoma, germ cell tumors, and hepatoblastoma (pages 3 & 12).

The document also highlights standard laboratory methods for AFP measurement—ELISA, RIA, chemiluminescent assays, and LC-MS/MS (page 5). Blood collection requires no fasting and no medication discontinuation, making AFP testing simple and patient-friendly (page 4).

Symptoms

AFP itself does not create symptoms; rather, the conditions associated with abnormal AFP levels produce noticeable clinical signs. The document shows how AFP abnormalities reflect underlying disease.

Symptoms When AFP Is High

Conditions such as hepatocellular carcinoma, germ cell tumors, liver cirrhosis, childhood hepatoblastoma, and gastrointestinal tumors (page 9) may present with:

1. Persistent fatigue
2. Unintentional weight loss
3. Abdominal discomfort or swelling
4. Jaundice
5. Nausea
6. Palpable lumps (in germ cell tumors)

Pregnancy-related AFP elevation may indicate neural tube defects, which may present with detectable abnormalities on prenatal imaging (page 10–11).

Symptoms When AFP Is Low

Low AFP levels in pregnancy are associated with Down syndrome or Edwards syndrome (page 8). Symptoms may not be directly visible but appear as abnormal findings on prenatal screening, growth restriction, or developmental concerns in the fetus.

For non-pregnant adults, AFP is naturally low and usually symptom-free.

Causes

The document includes detailed tables on low AFP causes (page 8) and high AFP causes (page 9).

Causes of Low AFP

1. Down syndrome (Trisomy 21): Maternal serum shows reduced AFP.
2. Edwards syndrome (Trisomy 18): Very low levels indicate chromosomal abnormality.
3. Increased maternal weight: Dilutional lowering of serum AFP.
4. Incorrect gestational dating: Pregnancy further along than estimated lowers AFP.
5. Fetal demise: Non-viable fetus stops producing AFP.
6. Hydatidiform mole: Abnormal placental tissue with absent fetus.
7. Normal adults/children: AFP is naturally very low outside neonatal age.

Causes of High AFP

1. Hepatocellular carcinoma: Significant elevation (+++).
2. Germ cell tumors: Including yolk sac tumors (+++).
3. Liver cirrhosis and hepatitis: Chronic liver damage (+).
4. Pregnancy: Physiological rise due to fetal AFP production (+).
5. Neural tube defects: Elevated maternal AFP (to ++).
6. Hepatoblastoma: Childhood liver tumor (+++).
7. Gastric/pancreatic cancer: Rare AFP-producing tumors (+).
8. Hereditary persistence: A Genetic condition causing persistent elevation.
9. Abdominal wall defects: AFP leaks into amniotic fluid (to ++).

These causes help clinicians understand why AFP levels fluctuate and how they relate to disease severity or fetal development.

Risk Factors

Risk factors for abnormal AFP align with the diseases and pregnancy-related conditions where AFP changes significantly.

1. Pregnancy-Related Risks (page 13)

1. Neural tube defects
2. Down syndrome
3. Edwards syndrome
4. High-risk pregnancies
5. Incorrect gestational dating
6. Fetal anomalies
7. Adverse pregnancy outcomes

2. Liver Disease Risks (pages 3 & 12)

1. Chronic hepatitis
2. Cirrhosis
3. Neonatal cholestasis
4. Hepatocellular carcinoma development
5. Individuals with cirrhosis are especially monitored because AFP aids in cancer risk assessment.

3. Cancer Risks (page 12)

1. Germ cell tumors
2. Hepatoblastoma
3. Gastric, pancreatic, or bowel tumors

4. Structural and Genetic Abnormalities in the Fetus

1. Neural tube defects
2. Chromosomal abnormalities such as Trisomy 21 and 18

Patients in these categories benefit from routine AFP monitoring to detect abnormalities early.

Prevention

AFP itself cannot be prevented because it is a marker, not a disease. However, the document offers essential steps to prevent testing errors, misinterpretation, and false positives.

1. Follow Proper Sample Collection Methods

(Page 4)

1. Collect 3.0 mL of blood in a plain red-capped tube.
2. Separate serum early and send promptly.

2. Use Accurate Testing Platforms

(Page 5)

1. ELISA
2. RIA
3. Chemiluminescent assay
4. LC-MS/MS
5. Using reliable assays reduces diagnostic confusion.

3. Avoid Misinterpretation

(Page 14)

1. AFP results must correlate with other markers.
2. Liver diseases can overlap with cancer levels.
3. AFP alone is not reliable for screening the general population.

4. Consider Pregnancy Variables

1. Incorrect dating, multiple pregnancies, or increased maternal weight can alter AFP.
2. Combine AFP with markers like hCG and uE3 (pages 10–11) for accurate screening.

5. Monitor High-Risk Patients Regularly

(Page 12–13)

Routine AFP tracking helps detect tumor progression, recurrence, and fetal abnormalities early.