LH – Luteinizing Hormone

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LH Luteinizing Hormone

Luteinizing Hormone (LH) is a hormone secreted by the anterior pituitary gland (a small endocrine gland in the base of the brain). Once secreted in men, it stimulates the testes to produce testosterone, which acts as the primary male hormone and is essential for the production of sperm.1

Similar to follicle stimulating hormone (FSH), which is also produced by the pituitary gland, LH plays a vital role in the hormonal status and reproductive ability of men. Abnormal levels (levels that are too high or too low) may indicate either a problem with testicular function or hypothalamic/pituitary function.

 

The Hypothalamic-Pituitary-Testicular Axis

In much the same production process as FSH, the anterior pituitary secretes luteinizing hormone in response to gonadotropin-releasing hormone (GnRH) that is, in turn, secreted by the hypothalamus (another small endocrine gland in the base of the brain). This axis also includes feedback mechanisms that inhibit production of LH when appropriate.

In males, LH triggers the production of testosterone by Leydig cells in the testes, which, of course, acts as an endocrine hormone and is essential for the production of sperm. Because it is part of the hypothalamic-pituitary-gonadal axis, its levels are regulated by stimulation and inhibition by GnRH and testosterone (T). Thus, when T levels are low, the hypothalamus is stimulated to increase production of GnRH. This increase in GnRH in turn stimulates LH production. Thus, high LH levels can be an indicator of low T. (Similarly, high FSH levels can also be an indicator of low T.)
 


 

LH Levels

Normal luteinizing hormone levels for an adult male should fall between 1.8 and 8.6 IU/L (IU/L = international units per liter).2 Several disease states are related to either increased or decreased levels. In general, levels progressively increase in aging males as testosterone levels concurrently decline.3 However, levels fail to increase appropriately in response to the decreasing T levels.

Most often in men, an LH test may be used to determine the cause for infertility, to determine the cause for low testosterone, or to aid in the diagnosis of pituitary or hypothalamus disorders.

Luteinizing Hormone

Description

1.8 – 8.6 IU/L Normal LH Levels

 

High LH Levels

High levels are generally seen with gonadal dysfunction (dysfunction with the testes). Gonadal dysfunction can be seen in a variety of diseases, including but not limited to testicular failure, congenital adrenal hyperplasia (a genetic adrenal gland disorder often causing increased or decreased levels of sex hormones), and gonadal dysgenesis (abnormal development of the gonads).4

With regard to T levels, if you have low testosterone and your LH levels are high, the testes themselves may not be working properly. Ideally, high LH and FSH levels should tell your testicles to increase testosterone production. However, if T levels remain low while LH levels are high, the problem likely lies with the testicles’ inability to produce testosterone.

Low LH Levels

Disease states with low levels include eating disorders, hypothalamic suppression, hypopituitarism, hyperprolactinemia (often in seen a certain type of brain tumor of the pituitary gland and sometimes associated with vision changes), and sex hormone deficiency among others.5

With regard to T levels, if you have low testosterone and your LH and FSH levels are low, the feedback loop in the hypothalamus/pituitary may not working properly. Ideally, low T levels should increase the secretion of GnRH and thus LH. However, if luteinizing hormone levels remain low when T levels are low, the problem is likely due to functional problems with the hypothalamus/pituitary.

Supplementation

Supplementation is mainly used by females in combination with FSH to increase fertility or to induce ovulation in women who have had a difficult time conceiving or during IVF (in vitro fertilization).6,7

Concluding Remarks

In conclusion, luteinizing hormone is an essential component of the hormonal system that regulates growth, development, and sexual reproduction in both males and females. It can be used as a marker with which to identify and monitor certain disease states and as a therapy for others.

Updated April 17, 2015

 

1. Bowen R. Gonadotropins: Luteinizing and Follicle Stimulating Hormones. Colorado State University. May 2004.

2. Burris CA, Ashwood ER, Burns DE. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 4th ed. St. Louis: Elsevier Saunders; 2006.

3. Morley JE, Kaiser FE, Perry HM III et al. Longitudinal changes in testosterone, luteinizing hormone and follicle stimulating hormone in healthy older men. Metabolism 1997; 46(4): 410-413.

4. Nguyen, HCT et al. Luteinizing Hormone. Medscape. http://emedicine.medscape.com/article/2089268-overview#a30.

5. Barker NM. Luteinizing Hormone Deficiency. Medscape Reference. 8/31/2010. Available at http://emedicine.medscape.com/article/255046-overview.

6. Mahesh VB. Hirsutism, virilism, polycystic ovarian disease, and the steroid-gonadotropin-feedback system: a career retrospective. AJP: Endocrinology and Metabolism 2011; 302 (1): E4-E18.

7. Dahan MH, Agdi M, Shehata F, Son W, Tan SL. A comparison of outcomes from in vitro fertilization cycles stimulated with either recombinant luteinizing hormone or human chorionic gonadotropin acting as an analogue delivered as human menopausal gonadotropins, in subjects with good or poor ovarian reserve: A retrospective analysis. Eur J Obstet Gynecol Reprod Biol. Jan 2014;172:70-3.