Luteinizing hormone (LH) blood test

Contributed by – Healthians Team

What is a luteinizing hormone (LH) blood test?

Luteinizing hormone (LH) test measures the levels of luteinizing hormone in the blood. The pituitary gland, a small gland located underneath the brain, is responsible for the production of LH. This hormone plays an important role in sexual development and functioning of the body. Too much or too little of LH in both men and women can lead to a variety of problems including infertility. 

Who should get tested?

Your doctor may order an LH blood test for many reasons.

If you are a woman, this may be ordered if –

• You have been unable to get pregnant after 12 months of trying
• You have an irregular menstrual cycle
• Your periods have stopped

And if you are a man, you may need this test if – 

• You have been unable to get your partner pregnant after 12 months of trying
• Your sex drive has decreased

An LH test is also ordered for both men and women when symptoms related to pituitary disorder are present. They include – 

• Fatigue
• Weakness
• Weight loss
• Decreased appetite

An LH test may be ordered for a child if he or she seems to be entering puberty too early or too late.

Why is the LH test needed?

In women, LH blood test helps to – 

• Find the cause of infertility
• Find out when ovulation occurs
• Understand the cause of irregular periods
• Know if menstrual periods have stopped
• Confirm the start of menopause or perimenopause

In men, LH test is often needed to – 

• Find the cause of infertility
• Find the reason for a low sperm count
• Understand the cause for low sex drive

And in children, LH tests are often used to diagnose early or late puberty.

What does LH test results mean?

Normal ranges of LH blood test are as follows – 

Note that these ranges are only for reference purposes. Test results may vary from lab to lab as each lab can have slightly varying ranges. Besides, your overall health and lifestyle can also influence your test results. Therefore, to correctly understand what your report says about your health, consult with a doctor.

Usually, higher than normal LH values in women indicate – 

• Problem with ovaries
• Polycystic ovary syndrome
• Turner syndrome

Low LH levels in women indicate – 

• Pituitary gland disorder
• Eating disorder
• Malnutrition

High LH levels in men mean – 

• Damaged testicles
• Klinefelter’s syndrome

Low LH levels in men mean – 

• Pituitary gland disorder
• Hypothalamus disorder

In children, high LH levels mean that puberty has started or is about to start. If it is happening before the age of 9, it may mean – 

• Central nervous system disorder
• Brain injury

And low LH levels in children may mean delayed puberty. It may be caused by – 

• Ovaries or testicles disorder
• Turner syndrome in girls
• Klinefelter’s syndrome in boys
• Infection
• Hormone deficiency
• Eating disorder

How is the test done?

A small sample of blood is needed to perform the LH test. It is usually drawn from a vein in the arm by a professional sample collector. Any kind of special preparation or fasting for several hours before the test is not required. But a woman getting the LH test may be asked to get the test done at a certain time during her menstrual cycle. Furthermore, inform your doctor about any pre-existing medical condition you might have or any medication you may be taking regularly as they can influence your test results.