The key difference between beta hCG and hCG is that beta hCG is the free form of the human chorionic gonadotropin, while hCG is the total form of human chorionic gonadotropin.
Human chorionic gonadotropin (hCG) is a hormone produced by the placenta of a pregnant woman after implantation. Beta hCG and hCG are two forms of hCG. The early detection of pregnancy is an important factor to ensure a safe pregnancy period. Thus, hCG test is the classic pregnancy detection test that is done on women. It is an easy test which detects the presence and level of hCG in the blood.
CONTENTS
1. Overview and Key Difference
2. What is Beta hCG
3. What is hCG
4. Similarities Between Beta hCG and hCG
5. Side by Side Comparison – Beta hCG vs hCG in Tabular Form
6. Summary
What is Beta hCG?
Beta hCG or beta human chorionic gonadotropin is a hormone. The human placenta secretes beta hCG. The name beta hCG arises due to the characteristic beta subunit that is present in the hormone. The beta hCG hormone consists of 145 amino acids. These acids are encoded by six different genes. These genes show high homology between them. They are mainly found as tandem repeats and as inverted pairs in the q arm on the chromosome 19. The beta hCG is a form of hCG in the free state. Therefore, it is easily detectable in blood.
Figure 01: Pregnancy Hormone Graph
The beta hCG also resembles the beta Luteinizing hormone (LH) in the structure. Beta hCG form plays an important role in pregnancy tests by acting as an early marker of pregnancy.
What is hCG?
hCG is also known as the human chorionic gonadotropin. This hormone is produced by the human placenta following implantation. Therefore, this hormone is used as a classic mode of detection for pregnancy. The hCG test done on women is also called the pregnancy test. However, apart from being an early marker of pregnancy, hCG can also act as a marker of cancer in cases where women are not pregnant.
Figure 02: hCG
The hCG is a glycoprotein composed of 237 amino acids and have a molecular weight of 36.7 kDa. Typical hCG glycoprotein has an alpha subunit and a beta subunit. The beta subunit is unique to the hCG protein while the alpha subunit also mimics with the subunit proteins of the luteinizing hormone and the follicle-stimulating hormone. In comparison, the beta subunit is larger than the alpha subunit. Overall, the hCG hormone has a hydrophobic core and a hydrophilic outer region. This enables the easy dissolution of the hormone.
The primary function of the hCG hormone is to maintain the corpus luteum during the beginning of pregnancy. This will facilitate the release of progesterone from the corpus luteum that will enrich the uterus with increased blood supply and sustain the growing fetus.
What are the Similarities Between Beta hCG and hCG?
- Both are used in the detection of pregnancy.
- They are secreted by the human placenta following pregnancy.
- Both can also act as cancer markers if the individual is not pregnant.
- They have the ability to protect the corpus luteum from degradation.
- Moreover, they allow the secretion of progesterone.
What is the Difference Between Beta hCG and hCG?
The difference between beta hCG and hCG relies on its ability to exist in the free state. Thus, beta hCG is the free form while total hCG is the bound form. Due to this nature, their chemical structure and the accuracy in detection also vary. The detection of beta hCG shows more accuracy in pregnancy test than the hCG detection test. Therefore, this is also a difference between beta hCG and hCG.
The below infographic summarizes the difference between beta hCG and hCG.
Summary – Beta hCG vs hCG
Human chorionic gonadotropin or hCG is a placental hormone. The total hCG is in the bound form. However, the beta form or the beta hCG is the free hCG that is present in humans. This is the key difference between beta hCG and hCG hormone. However, the accuracy in detecting the two types vary. Beta hCG is more accurate in detection than total hCG. Collectively, both forms are used in pregnancy detection as it is secreted by the placenta during pregnancy. In the absence of a pregnant condition, the presence of both forms of hCG in blood may suggest a presence of cancer. So, this is the summary of the difference between beta hCG and hCG.
Reference:
1. Hsieh, Tsang-Tang, et al. “Total HCG versus Free Beta-HCG Combined with Alpha-Fetoprotein for Down Syndrome Screening in Taiwan.” Taiwanese Journal of Obstetrics & Gynecology, U.S. National Library of Medicine, Sept. 2007, Available here.
Image Courtesy:
1. “Pregnancy hormone graph” By Osmosis – open.osmosis.org (CC BY-SA 4.0) via Commons Wikimedia
2. “HCG structure” By Borislav Mitev – borislav_mitev@hotmail.com – PyMOL (Public Domain) via Commons Wikimedia