Alpha-Fetoprotein (AFP)

Overview

Alpha-fetoprotein (AFP) is a protein produced by the liver and yolk sac of a developing fetus during pregnancy. It serves as a carrier protein, similar to albumin, transporting substances like fatty acids to cells^[1]. AFP levels in maternal blood are used to screen for fetal abnormalities, such as neural tube defects and chromosomal disorders like Down syndrome^[2]. In adults, elevated AFP levels can indicate certain cancers, including liver cancer and testicular cancer^[4].

Scientific Background

AFP is synthesized by the fetal liver and yolk sac, peaking in maternal plasma during the first trimester and decreasing after birth^[1]. Its function in adults is unclear, but it may have immunoregulatory properties^[3]. In rodents, AFP binds estradiol, preventing its transfer to the fetus and thus preventing virilization of female fetuses^[1]. In humans, AFP does not bind estrogen, making its role less clear^[1].

Measurement and Testing

A blood test measures AFP levels in pregnant women, typically between 15 and 22 weeks of gestation^[2]. This test is part of a quadruple screen that includes other markers like hCG and estriol^[5]. Factors affecting results include gestational age and multiple pregnancies^[5].

Reference Ranges

Normal AFP levels vary by laboratory but are generally less than 40 micrograms per liter in nonpregnant individuals^[4]. Levels increase during pregnancy and decrease after birth^[4]. Demographic variations include higher levels in multiple pregnancies and lower levels in chromosomal abnormalities like Down syndrome^[5].

High Values

Elevated AFP levels can indicate open neural tube defects, abdominal wall defects, or certain cancers like hepatocellular carcinoma^[1][4]. High levels during pregnancy may suggest a miscalculated due date or multiple fetuses^[5].

Low Values

Low AFP levels are associated with chromosomal abnormalities such as Down syndrome and Edwards syndrome^[2][5]. They may also indicate a miscalculated gestational age^[5].

Improving Biomarker Levels

Improving AFP levels is not typically a goal, as it is primarily used for diagnostic purposes. However, addressing underlying conditions (e.g., liver disease) can normalize AFP levels^[4]. Lifestyle modifications are not directly linked to altering AFP levels.

Importance of Tracking

Tracking AFP levels is crucial for identifying potential fetal abnormalities and monitoring certain cancers^[1][4]. It aids in decision-making for further diagnostic tests and interventions^[5].

Disclaimer

The information provided in this document is for educational purposes only and does not constitute medical advice. It is essential to consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.