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LH

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Also known as: Luteinizing Hormone; Lutropin; Interstitial Cell Stimulating Hormone; ICSH
Formal name: Luteinizing Hormone, serum or urine

At a Glance

Why Get Tested?

To evaluate fertility issues, function of reproductive organs (ovaries or testicles), or to detect the release of an egg from the ovary (ovulation); to evaluate pituitary function

In children, to evaluate early or delayed sexual maturation (puberty)

When to Get Tested?

For women, when you are having difficulty getting pregnant or are having irregular or heavy menstrual periods; when you are tracking ovulation during your menstrual cycle

For men, when your partner cannot get pregnant or you have a low sperm count, low muscle mass or decreased sex drive

When your healthcare provider thinks that you have symptoms of a pituitary disorder or hypothalamic disorder

When a health practitioner suspects that a child has delayed or earlier than expected sexual maturation

Sample Required?

A blood sample drawn from a vein in your arm; sometimes a random urine sample or a 24-hour urine collection may be taken

Test Preparation Needed?

None, but the timing of a woman's sample will be correlated with her menstrual cycle.

The Test Sample

What is being tested?

Luteinizing hormone (LH) is a hormone associated with reproduction and the stimulation of the release of an egg from the ovary (ovulation) in women and testosterone production in men. This test measures the amount of luteinizing hormone in the blood or urine.

LH is produced by the pituitary gland, a grape-sized organ found at the base of the brain. Control of LH production is a complex system involving the hypothalamus in the brain, the pituitary gland, and the hormones produced by the ovaries and testicles.

In premenopausal women, several hormones rise and fall in a specific sequence during each menstrual cycle. During the cycle, LH stimulates ovulation and the production of other hormones, estradiol and progesterone.

Womens' menstrual cycles are divided into follicular and luteal phases, with each phase lasting about 14 days. Near the end of the follicular phase, there is a mid-cycle surge of follicle-stimulating hormone (FSH) and LH. This surge triggers ovulation, causing the rupture of the egg follicle on the ovary and the release of the egg.

During the luteal phase, the site where the egg follicle ruptured becomes a "corpus luteum." LH secretion stimulates the corpus luteum to start producing progesterone. FSH and LH levels decline, while progesterone and estradiol concentrations increase. These hormone levels decrease in turn after several days if the egg is not fertilized. Menstruation starts and when it ends, the cycle begins again.

As a woman ages and menopause approaches, ovarian function wanes and eventually ceases. As this occurs, FSH and LH levels rise.

In men, LH stimulates Leydig cells in the testicles to produce testosterone. LH levels are relatively constant in men after puberty. A high testosterone level provides negative feedback to the pituitary gland and the hypothalamus, thus decreasing the amount of LH secreted.

In infants and children, LH levels rise shortly after birth and then fall to very low levels (by 6 months in boys and 1-2 years in girls). At about 6-8 years, levels again rise before the beginning of puberty and the development of secondary sexual characteristics.

How is the sample collected for testing?

A blood sample is taken by needle from a vein in the arm or a random urine sample is used. A 24-hour collection of urine may be requested if a health practitioner wants to measure LH levels produced over a 24-hour period. LH is released intermittently throughout the day; thus, a random sample may not reflect a true reading. A 24-hour urine can eliminate this variation.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

Is any test preparation needed to ensure the quality of the sample?

No test preparation is needed, but a woman's sample should be collected at specific times during her menstrual cycle.

The Test

Common Questions

Ask a Laboratory Scientist

Article Sources

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.

Sources Used in Current Review

Barker, N, et, al. (Updated 2012 March 23). Luteinizing Hormone Deficiency. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/255046-overview through http://emedicine.medscape.com. Accessed April 2014.

Dowshen, S. (2011 March). Blood Test: Luteinizing Hormone (LH). KidsHealth from Nemours [On-line information]. Available online at http://kidshealth.org/parent/system/medical/blood_test_lh.html through http://kidshealth.org. Accessed April 2014.

Kaplowitz, P. (Updated 2013 February 11). Precocious Puberty. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/924002-overview through http://emedicine.medscape.com. Accessed April 2014.

Meikle, A. and Straseski, J. (Updated 2013 November). Infertility. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Infertility.html?client_ID=LTD#tabs=0 through http://www.arupconsult.com. Accessed April 2014.

Bielak, K. and Popat, V. (Updated 2012 June 5). Amenorrhea. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/252928-overview through http://emedicine.medscape.com. Accessed April 2014.

(© 1995–2014). LH. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/8663 through http://www.mayomedicallaboratories.com. Accessed April 2014.

Vorvick, L. (2013 September 30). LH blood test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003708.htm through http://www.nlm.nih.gov. Accessed April 2014.

Pagana, K. D. & Pagana, T. J. (© 2011). Mosby's Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 649-651.

Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry 2nd Edition: AACC Press, Washington, DC. Pp 471-479.

Sources Used in Previous Reviews

Corbett, JV. Laboratory Tests & Diagnostic Procedures with Nursing Diagnoses, 4th ed. Stamford, Conn.: Appleton & Lang, 1996. pp. 429-431, 726.

Clinical Guide to Laboratory Tests. 3rd ed. Tietz N, ed. Philadelphia: W.B. Saunders & Co; 1995: 248-249, 210-211.

The InterNational Council on Infertility Information Dissemination. PCOS in Pediatrics: When and How Does it Start? Originally written and presented by Silva Arslanian, MD, Children's Hospital of Pittsburgh, Pittsburgh, PA; summarized in online version by Christine M. Schroeder, PhD. Available online at http://www.inciid.org/pcos/PCOS-pediatrics.html through http://www.inciid.org.

Gonadotropins: Luteinizing and Follicle Stimulating Hormones. Available online at http://arbl.cvmbs.colostate.edu/hbooks/pathphys/endocrine/hypopit/lhfsh.html through http://arbl.cvmbs.colostate.edu.

Blondell RD, Foster MB, Kamlesh CD. Disorders of Puberty. American Family Physician, July 1999 (online publication). Available online at http://www.aafp.org/afp/990700ap/209.html through http://www.aafp.org.

Hormone Society. Fact Sheet on Female Infertility. Available online at http://www.endo-society.org/pubrelations/patientInfo/infertility.htm through http://www.endo-society.org.

The Hormone Foundation. Fact sheet on Polycystic Ovary Syndrome (PCOS). Available online at http://www.hormone.org/pcos_factsheet.html through http://www.hormone.org.

Laurence M. Demers, PhD. Distinguished Professor of Pathology and Medicine, The Pennsylvania State University College of Medicine, The M. S. Hershey Medical Center, Hershey, PA.

A Manual of Laboratory & Diagnostic Tests. 6th ed. Fischbach F, ed. Philadelphia: Lippincott Williams & Wilkins; 2000.

Pagana K, Pagana T. Mosby's Manual of Diagnostic and Laboratory Tests. St. Louis: Mosby; 1998.

Davis B, Mass D, Bishop M. Principles of Cinical Laboratory Utilization and Consultation. Saunders; 1999.

Thompason, Sharon. LH response to GnRH. (Updated Aug 2005) MedlinePlus (online information). Available online at http://www.nlm.nih.gov/medlineplus/print/ency/article/003709.htm.

Neely EK, Wilson DM, Lee PA, Stene M, Hintz RL (July 1995). Spontaneous serum gonadotropin concentrations in the evaluation of precocious puberty. J Pediatric 127(1):47-52 from PubMed. Available online at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&dopt=Abstract&list_uids=7608810 through http://www.ncbi.nlm.nih.gov.

Nirupama Kakarla, M.D.; Karen D. Bradshaw, M.D. (Posted 03/05/2004.) Disorders of Pubertal Development: Precocious Puberty. From Seminars in Reproductive Medicine 21(4):339-351 from Medscape. Available online at http://www.medscape.com/viewarticle/468259 through http://www.medscape.com.

Brito VN, Batista MC, Borges MF, Latronico AC, Kohek MB, Thirone AC, Jorge BH, Arnhold IJ, Mendonca BB. (1999 Oct) Diagnostic value of fluorometric assays in the evaluation of precocious puberty. J Clin Endocrinol Metab. 84(10):3539-44.

Sheehan, M (Dec 2003). Polycystic Ovarian Syndrome: Diagnosis and Management. Clinical Medicine and Research, 2(1): 13-27. Available online at http://www.pubmedcentral.gov/articlerender.fcgi?artid+1069067 through http://www.pubmedcentral.gov.

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby's Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 629-631.

Wu, A. (© 2006). Tietz Clinical Guide to Laboratory Tests, 4th Edition: Saunders Elsevier, St. Louis, MO. Pp 694-697.

Vorvick, L. (Updated 2009 July 29). LH. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003708.htm. Accessed February 2010.

Giannios, N. et. al. (Updated 2008 February 12). Luteinizing Hormone Deficiency. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/255046-overview through http://emedicine.medscape.com. Accessed February 2010.

Meikle, A. W. et. al. (Updated 2009 November). Amenorrhea. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/Amenorrhea.html# through http://www.arupconsult.com. Accessed February 2010.

Brzyski, R. and Jensen, J. (Revised 2007 March) Female Reproductive Endocrinology, Introduction. Merck Manual for Healthcare Professionals [On-line information]. Available online at http://www.merck.com/mmpe/sec18/ch243/ch243a.html?qt=FSH&alt=sh through http://www.merck.com. Accessed February 2010.

Clarke, W. and Dufour, D. R., Editors (© 2006). Contemporary Practice in Clinical Chemistry: AACC Press, Washington, DC. Pp 360-361.

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