AFP test assay is intended for the use as:
▪ An aid in the diagnosis of hepatocellular carcinoma (HCC).
▪ An aid in the management of patients with non‑seminomatous germ cell tumors
Clinical significance:
AFP ( alpha-fetoprotein) is a glycoprotein that is normally produced during gestation by fetal liver yolksac, and the fetal gastrointestinal tract . It is present in high levels in the blood of pregnant women, but levels drop sharply after birth.
Alpha1‑fetoprotein (AFP), an albumin‑like glycoprotein with a molecular weight of approximately 70 kDa, is formed in the yolk sac during fetal life, in non‑differentiated liver cells, and the fetal gastro‑intestinal tract
Role of AFP in hepatocellular carcinoma
AFP has long been recognized as a biomarker for HepatoCellular Carcinoma (HCC), and has played a prominent role in the diagnosis of HCC. AFP may regulate the growth of neoplastic and normal cells by several mechanisms that include apoptotic regulation and cytoplasmic signalling modulation.
AFP levels tend to increase with the size of the liver tumor. Larger tumors are more likely to produce higher levels of AFP. This correlation is helpful in assessing the extent and severity of the disease.
Diagnosis of HCC has primarily relied on the presence of typical features seen on contrast-enhanced imaging studies, histopathological assessment, and serum AFP levels
70 to 95% of patients with primary hepatocellular carcinoma have elevated AFP values.
Role of AFP in non‑seminomatous germ cell tumors
The measurement of AFP in serum, in conjunction with serum hCG, is an established regimen for monitoring patients with nonseminomatous testicular cancer. One or both of the markers are elevated in about 90% of patients with non-seminomatous testicular tumors2.
Reference range for AFP
Normal reference range is < 7 ng/ml.
Adult blood levels greater than 200 ng/ml in patients with liver cirrhosis strongly indicate hepatocellular carcinoma1.
Interpretation of AFP Test :
AFP is increased in
Primary hepatocellular carcinoma, teratocarcinoma, yolksac tumour, nonseminomatous testicular cancer, ovarian tumours.
Benign hepatic conditions such as acute viral hepatitis ,chronic active hepatitis, cirrhosis, alcohol abuse.
Limitations:
AFP is not recommended as a screening test to detect cancer in general population.
AFP values should be interpreted in context with clinicoradiological findings.
In rare cases heterophile antibodies in serum can react with reagent immunoglobulin and cause interference in results, particularly seen in persons exposed to animals and animal serum products .
This test may exhibit interference when the sample is collected from a person who is consuming a high dose of biotin (>5mg/day) Patients should be cautioned to stop biotin consumption at least 8 hours before collection of the sample.
References:
1.Adigun OO, Yarrarapu SNS, Zubair M, et al. Alpha Fetoprotein. [Updated 2023 Jan 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430750/
2.Dieckmann KP, Simonsen-Richter H, Kulejewski M, Anheuser P, Zecha H, Isbarn H, Pichlmeier U. Serum Tumour Markers in Testicular Germ Cell Tumours: Frequencies of Elevated Levels and Extents of Marker Elevation Are Significantly Associated with Clinical Parameters and with Response to Treatment. Biomed Res Int. 2019;2019:5030349. [PMC free article] [PubMed].
3.Henry’s clinical diagnosis and management by laboratory methods,23rd edition.
4.Wallach’s interpretation of diagnostics tests, 12th edition.