Reference Intervals of Alpha-Fetoprotein and Carcinoembryonic Antigen in the Apparently Healthy Population

BACKGROUND: The aim of this study was to calculate 95% reference intervals and double-sided limits of serum alpha-fetoprotein (AFP) and carcinoembryonic antigen (CEA) according to the CLSI EP28-A3 guideline. MATERIAL/METHODS: Serum AFP and CEA values were measured in samples from 26 000 healthy subjects in the Shuyang area receiving general health checkups. The 95% reference intervals and upper limits were calculated by using MedCalc. RESULTS: We provided continuous reference intervals from 20 years old to 90 years old for AFP and CEA. The reference intervals were: AFP, 1.31–7.89 ng/ml (males) and 1.01–7.10 ng/ml (females); CEA, 0.51–4.86 ng/ml (males) and 0.35–3.45ng/ml (females). AFP and CEA were significantly positively correlated with age in both males (r=0.196 and r=0.198) and females (r=0.121 and r=0.197). CONCLUSIONS: Different races or populations and different detection systems may result in different reference intervals for AFP and CEA. Continuous reference intervals of age changes are more accurate than age groups.