Luteinizing hormone (LH) is a hormone produced in the anterior pituitary gland involved in regulation of the reproductive function. Specifically, gonadotropic cells in the anterior pituitary gland produce LH or Luteinizing hormone LH SLH production is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. An acute surge in LH levels triggers ovulation and the development of the corpus luteum in females. In males, LH is also called interstitial cell-stimulating hormone (ICSH). They act on the Leydig cells to produce testosterone and work in synergy with the follicle-stimulating hormone (FSH).
The hormone is a heterodimeric glycoprotein that comprises of one alpha and one beta subunits that are non-covalently associated. The alpha subunit in humans contains 92 amino acids whereas the beta subunit varies in its composition, but generally is of 120 amino acids long.
What is the action of luteinizing hormone LH? The beta subunit is responsible for luteinizing hormones’ biological activity and interaction specificity with the LH receptor. The difference in these subunit compositions regulates the bioactivity and degradation speed of luteinizing hormone. The alpha subunit gene is on chromosome 6q12.21 while the gene for the beta subunit is on chromosome 19q13.32.
Luteinizing hormone (LH) is also known as lutrophin, lutropin, LHB, LH-B, LSH-beta, hLSB, LSH-B, and Lutropin subunit beta.
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We, at NorthEast BioLabs, perform the luteinizing hormone test to detect LH in your samples. We use MSD, ELISA, and Luminex assays that are highly precise in LH detection. Researchers use these assays to understand the functions of luteinizing hormone. Following is a typical ELISA protocol explained.
We begin the luteinizing hormone test with a pre-coated monoclonal antibody microtiter plate and add 50 μl of samples or standard in appropriate wells. The antibody is specific to LH. Therefore, if LH is present in the samples, it will bind to the pre-coated antibody. To quantify LH concentrations, we introduce an HRP-conjugated antibody in each well. This antibody achieves the sandwich effect in the reaction. Post-incubation, we add TMB substrate solution and allow it to react with the HRP enzyme. Wells containing enzyme-conjugated antibody and LH will show color change with the intensity of the color varying the hormonal concentration in the sample. We then add sulphuric acid to end the reaction and spectrophotometrically measure the color change at 450 nm.
We compare the optical density of the luteinizing hormone/ LH samples with the standard curve and determine the LH concentrations. The LH hormone assay is highly sensitive and can detect a minimum LH concentration of 3 mlU/ml.
Both high and low levels of luteinizing hormones can cause infertility in males and females. In women, research has correlated high LH levels with polycystic ovary syndrome. Low levels of LH reduce the production of eggs and sperms and thus affects reproductive efficacy. Several medications are available for LH dysregulation. Researchers have developed menotropin, a mixed form of LH and FSH, and lutropin alfa, a recombinant LH, to stimulate the development of the follicles and use them in infertility therapy.
To learn more about LH functions, explore the resources below.
https://medlineplus.gov/lab-tests/luteinizing-hormone-lh-levels-test/
https://www.webmd.com/a-to-z-guides/luteinizing-hormone-test#1
https://www.hormone.org/your-health-and-hormones/glands-and-hormones-a-to-z/hormones/luteinizing-hormone
https://www.healthline.com/health/lh-blood-test
https://www.yourhormones.info/hormones/luteinising-hormone/
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The hypothalamic-pituitary-gonadal axis is a finely tuned system that regulates luteinizing hormone secretion from the gonadotropic cells. The hypothalamus secretes a gonadotrophin-releasing hormone that binds to the receptors of the anterior pituitary gland and triggers the synthesis and release of luteinizing hormone. The secreted luteinizing hormone reaches the ovaries and testes and binds to the receptors to stimulate hormone secretion and egg or sperm production. This hormonal release also suppresses gonadotrophin-releasing hormone secretion, which in turn suppresses the release of luteinizing hormone thus regulating its release through a feedback loop. When the hormonal levels fall, gonadotrophin-releasing hormone and luteinizing hormone level rise. This phenomenon is called negative feedback. In women, progesterone and estrogen exert this negative feedback, and testosterone does the same in men.
Luteinizing hormone function plays a crucial role in regulating sexual functioning and development and also regulates the menstrual cycle in women. It triggers egg release from the ovary, also called ovulation. Just before ovulation, the LH hormone levels surge quickly in women and therefore several luteinizing hormone tests use this concept to predict the rise of LH in women, thus aiding in determining the time of ovulation.