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[Biochemistry](https://durgical.com/en/biochemistry/) · Topic

# Alpha-fetoprotein (AFP)

AFP is the 'fetal albumin'; in adults it rises in liver cancer and germ cell tumours, and in pregnancy it flags neural tube defects.

Updated 2026-11-01

## Key facts

- A glycoprotein made by the yolk sac and fetal liver; in adults it almost disappears.
- Marker of hepatocellular carcinoma and non-seminomatous germ cell tumours (yolk sac); pure seminoma makes no AFP.
- In pregnancy, high maternal AFP: open neural tube defects, abdominal wall defects, multiple pregnancy or wrong dates; low: risk of trisomy 21 (with other markers).
- It also rises in acute and chronic hepatitis and cirrhosis (liver regeneration), without cancer.
- Reference values and cut-offs vary by laboratory and, in pregnancy, by gestational week.

## In detail

- What it measures: serum AFP concentration (in pregnancy reported as multiples of the median, MoM, for that week).
- Where it comes from: fetal liver and yolk sac make it as a carrier protein; tumours with a fetal phenotype express it again.
- Why it rises: hepatocellular carcinoma, hepatoblastoma, yolk sac tumour, embryonal carcinoma, liver regeneration, ataxia-telangiectasia, tyrosinaemia type 1.
- Pitfalls: a third or more of small hepatocellular carcinomas do not raise it; active hepatitis can raise it without cancer; in pregnancy the gestational age must be known accurately.
- A seminoma with a high AFP is managed as non-seminomatous, because it has a component that makes it.

**Also called**
AFP, α-fetoprotein

## Clinical notes

- In cirrhosis, a steadily rising AFP calls for imaging to look for hepatocellular carcinoma.
- With β-hCG and LDH it stages testicular germ cell tumours.
- Prenatal screening with AFP is combined with ultrasound; preconception folic acid reduces neural tube defects.

## Related conditions

- [Hepatocellular carcinoma](https://durgical.com/en/conditions/hepatocellular-carcinoma/)
- [Testicular cancer](https://durgical.com/en/conditions/testicular-cancer/)
- [Cirrhosis](https://durgical.com/en/conditions/cirrhosis/)
- [Viral hepatitis](https://durgical.com/en/conditions/viral-hepatitis/)
- [Spina bifida (myelomeningocele)](https://durgical.com/en/conditions/spina-bifida/)

## Related

- [Tumour markers: principles of use](https://durgical.com/en/biochemistry/topics/tumour-markers-principles-of-use/)
- [Serum albumin as a lab test](https://durgical.com/en/biochemistry/topics/serum-albumin-as-a-lab-test/)
- [Liver function tests: reading the pattern](https://durgical.com/en/biochemistry/topics/liver-function-tests-reading-the-pattern/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which fetal tissues make AFP?

The yolk sac and fetal liver; adults make almost none.

## Which testicular tumour does not make AFP?

Pure seminoma; a seminoma with a high AFP is treated as having a non-seminomatous component.

## What does a high second-trimester maternal AFP suggest?

An open neural tube or abdominal wall defect, a multiple pregnancy or wrong gestational dates.

## Why does a normal AFP not rule out hepatocellular carcinoma?

Many such tumours, especially small ones, do not raise it; so surveillance relies on ultrasound.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Alpha Fetoprotein (AFP) Tumor Marker Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/alpha-fetoprotein-afp-tumor-marker-test/) (MedlinePlus, US National Library of Medicine, 2026); [Alpha-Fetoprotein (AFP) Test: MedlinePlus Medical Test](https://medlineplus.gov/lab-tests/alpha-fetoprotein-afp-test/) (MedlinePlus, US National Library of Medicine, 2026); [Alpha fetoprotein: MedlinePlus Medical Encyclopedia](https://medlineplus.gov/ency/article/003573.htm) (MedlinePlus, US National Library of Medicine, 2026); Textbook of Biochemistry for Medical Students, 6th ed. (Jaypee Brothers Medical Publishers (Vasudevan DM, Sreekumari S, Vaidyanathan K), 2011).

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