Luteinizing Hormone (LH)

Luteinizing Hormone (LH)

Definition: Luteinizing hormone (LH) is a gonadotropin produced and secreted by the anterior pituitary gland. It plays a crucial role in regulating reproductive functions in both males and females.

Functions of Luteinizing Hormone

• In Females:

• Ovulation: LH surges mid-cycle, triggering ovulation—the release of a mature egg from the ovary.
• Corpus Luteum Formation: After ovulation, LH stimulates the formation of the corpus luteum, which produces progesterone to maintain the uterine lining for potential implantation.

• In Males:

• Testosterone Production: LH stimulates Leydig cells in the testes to produce testosterone, which is essential for sperm production and the development of male secondary sexual characteristics.

Regulation of LH Secretion

• Hormonal Control: LH secretion is regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus. The pulsatile release of GnRH stimulates the pituitary gland to produce and release LH.
• Feedback Mechanism: Estrogen and progesterone in females and testosterone in males exert negative feedback on LH production, regulating its levels based on reproductive needs.

Clinical Relevance

• Infertility: Abnormal LH levels can indicate issues with ovulation in women or testosterone production in men, leading to fertility problems.
• Polycystic Ovary Syndrome (PCOS): Women with PCOS often have elevated LH levels, which can disrupt normal ovarian function.
• LH Testing: Blood tests measuring LH levels are commonly used to assess reproductive health and diagnose various conditions related to hormonal imbalances.

Conclusion

Luteinizing hormone is vital for reproductive health, influencing ovulation in females and testosterone production in males. Understanding its functions and regulation is essential for diagnosing and managing reproductive disorders.

References

1. Melmed S, et al. “The Pituitary.” 4th ed. Elsevier; 2016.
2. Finkelstein JW, et al. “Luteinizing hormone: physiology and clinical significance.” Endocrine Reviews. 1990; 11(3): 291-307. DOI: 10.1210/edrv-11-3-291
3. Rosenfield RL. “Clinical review: The polycystic ovary syndrome.” The Journal of Clinical Endocrinology & Metabolism. 2000; 85(5): 1997-2006. DOI: 10.1210/jcem.85.5.6612