Related Subjects:
|Ferritin
|CEA
|ESR
|CRP
|ALP
|LDH
|HbA1c
|Alpha Fetoprotein
|Anti-Hu ab
|Biochemical Lab values
๐งช Alpha-Fetoprotein (AFP) is a tumour marker most often used alongside ฮฒ-hCG to monitor Non-Seminomatous Germ Cell Tumours (NSGCT).
It is also clinically important in hepatocellular carcinoma (HCC) and pregnancy-related conditions.
๐ About
- Tumour marker with a relatively high incidence of false positives and false negatives.
- Best used for monitoring disease course and treatment response once a diagnosis is confirmed, rather than as a screening test.
- Serum AFP often rises prior to treatment and declines with effective therapy, making it a useful dynamic marker.
๐งฌ AFP as a Marker
- ๐ฏ NSGCT of the Testis (raised in ~50โ70%).
- ๐ฏ NSGCT at other sites (40โ60% of cases, rarely stage I).
- ๐ฏ Ovarian NSGCT.
- ๐ฉธ Hepatocellular Carcinoma (HCC) โ elevated in 70โ90% (threshold >500 ng/mL strongly suggestive).
- ๐ง Hepatoblastoma โ mainly in children, rare in adults.
๐งพ Sample Requirements
- โ ๏ธ Avoid interference: if on high-dose biotin therapy (>5 mg/day), collect sample โฅ8 hours after last dose.
- Adults: blood sample in a 5 mL gold-top gel tube (or rust-top in the Acute Unit).
๐ถ Normal Physiology
- In pregnancy, AFP is produced by the yolk sac, fetal GI tract, and liver.
- Passes via the placenta into maternal circulation โ basis of maternal serum AFP testing.
- Structurally related to albumin; encoded by a gene on chromosome 4 (q arm).
๐ Causes of High AFP
- Adults:
- Hepatocellular carcinoma (AFP >500 ng/mL is highly specific, though 10% remain normal).
- Other liver pathology: acute viral hepatitis, alcoholic hepatitis, drug-induced hepatitis.
- Used in combination with liver ultrasound for hepatoma screening.
- Children: Ataxiaโtelangiectasia.
- Pregnancy: Neural tube defects, multiple pregnancy, abdominal wall defects, fetal growth restriction, eclampsia, fetal loss.
๐ Causes of Low AFP
- Downโs Syndrome: Reduced maternal serum AFP is part of the triple/quadruple test in prenatal screening.
- NSGCT: In testicular nonseminoma, falling AFP suggests treatment response, while rising AFP indicates relapse.
๐ Clinical Pearls
- AFP is not a screening tool due to limited sensitivity and specificity.
- Its greatest utility is in trend monitoring (rise or fall over time).
- Interpret AFP in context with ฮฒ-hCG, LDH, imaging, and clinical findings.
