Luteinizing Hormone (LH)

Take-home points

• The testicles need luteinizing hormone to produce testosterone and sperm.  
• Abnormal levels of luteinizing hormone can indicate a testosterone deficiency, testicular damage and other health problems.
• If you are experiencing symptoms of low testosterone (sexual dysfunction, muscle loss, weakness and fatigue), consult a healthcare professional for evaluation and guidance.  

What is luteinizing hormone and where is it released from?

The luteinizing hormone is a chemical messenger, produced by the pituitary gland in the brain.  

What does luteinizing hormone do in males?

Among a few of its roles in the body, the luteinizing hormone stimulates the testicles to produce sex hormones. In men, testosterone and sperm production relies on the luteinizing hormone.¹

During puberty, luteinizing hormone levels increase, stimulating testosterone production and driving the physical changes associated with sexual maturation, such as deepening of the voice, growth of facial and body hair, and development of muscle mass.² In adulthood, luteinizing hormone levels generally remain within the normal range, crucial for maintaining male characteristics and reproductive function.¹

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Measuring luteinizing hormone and follicle-stimulating hormone (LH & FSH)

With luteinizing hormone's key role in men’s health, it is routinely measured through blood tests as part of a diagnostic evaluation by healthcare professionals if suspected symptoms are present. It is often measured alongside follicle-stimulating hormone (FSH), a separate hormone released by the pituitary gland to stimulate the testes to drive sperm production.¹  

Learn more about the role of follicle-stimulating hormone here

What are normal levels of luteinizing hormone in men?

In adult men below 70 years old, normal luteinizing hormone levels are between 0.7–7.9 IU/L. In men above 70 years old, the normal range increases to 3.1–34.0 IU/L. Luteinizing hormone levels tend to be relatively stable in men throughout the day, with minor fluctuations.

Keep in mind that these ranges can vary depending on how luteinizing hormone is measured, so check with your healthcare professional if tested.  

What do high or low levels of luteinizing hormone indicate?

High levels of luteinizing hormone in men can indicate various underlying health conditions:

• Impaired or damaged testicles: High luteinizing hormone levels can indicate that the pituitary gland is trying to compensate for impaired or damaged testicles. For this reason, a high LH level is often used to diagnose testicular failure.³
• Primary Hypogonadism: High luteinizing hormone coupled with low testosterone levels and related symptoms would strongly indicate primary hypogonadism, a condition where the testicles are unable to produce adequate testosterone. Primary hypogonadism is often the result of testicular failure, Klinefelter syndrome (born with an extra copy of the X chromosome) or autoimmune disorders that affect the testicles.³
• Testicular tumours: The type of cells in the testicles that produce luteinizing hormone are called Leydig cells. One sign of a Leydig cell tumour is excessive luteinizing hormone production, causing elevated levels of luteinizing hormone in the blood.⁴
• Pituitary Disorders: Rare conditions that disrupt the pituitary gland can cause elevated luteinizing hormone levels. For example, pituitary hyperplasia.¹

Conversely, low levels of luteinizing hormone in men may indicate:

• Secondary hypogonadism (hypogonadotropic hypogonadism): Whereas the pituitary works in overdrive in primary hypogonadism, secondary hypogonadism centres on defects in the brain that result in insufficient/low production of the luteinizing hormone. Testosterone levels remain low as a result. The causes of secondary hypogonadism include genetic disorders, pituitary tumours and certain medications.³
• Chronic Illness: Serious medical conditions such as liver disease⁵ and diabetes⁶ can suppress the production of luteinizing hormone.  
• Obesity: Obesity has been associated with decreased luteinizing hormone levels in men, possibly due to disruptions in hormone regulation caused by excess body fat.⁷  

Understanding the significance of the luteinizing hormone is crucial for identifying underlying health issues and initiating appropriate treatment. If you have concerns about your hormonal health, particularly if you are experiencing symptoms of low testosterone (sexual dysfunction, muscle loss, weakness and fatigue), consult a healthcare professional for evaluation and guidance.

Learn more about symptoms, diagnosis, and treatment of low testosterone by clicking here

References

1. Physiology, Luteinizing Hormone.(Accessed February 2024)
2. Dunkel L et al. J Clin Endocrinol Metab 1992;74(4):890–897
3. Dandona P & Rosenberg MT. Int J Clin Pract 2010;64(6):682–696
4. Liu G et al. N Engl J Med 1999;341(23):1731–1736
5. Baker HW et al. Q J Med 1976;45(177):145–178
6. Ballester J et al. J Androl 2004;25(5):706–719
7. Lima N et al. Int J Obes Relat Metab Disord 2000;24(11):1433–1437