Luteinising hormone (LH)

The luteinising hormone test checks the level of luteinising hormone (LH) in the blood. The pituitary gland, a small gland positioned underneath the brain, produces the luteinising hormone. This hormone plays a vital role in sexual function and development.

Its function includes:

• In women – LH helps to control the menstrual cycle. This hormone also triggers the ovary to release an egg (ovulation), so LH levels rise quickly before ovulation
• In men – LH triggers testosterone production from the testicles, which is essential for sperm production. LH levels in men do not usually change much.
• In children – LH levels are often low during early childhood but gradually rise a few years before the onset of puberty. In girls, LH signals the ovaries to produce oestrogen. In boys, it signals the testes to produce testosterone

Excess or insufficient LH can cause different problems, including menstrual difficulties in women, delayed or early puberty, low sex drive in men and infertility.

LH is also known as interstitial cell-stimulating hormone or lutropin.

What is the LH test for?

LH mostly works with the follicle-stimulating hormone (FSH) to control sexual function, so most doctors order the LH and FSH tests together. The tests have different functions, depending on if you are a child, man or woman.

In women, the FSH and LH tests have the following functions.

• Help determine the cause of infertility
• Check the cause of stopped or irregular menstrual periods
• Check for perimenopause or the onset of menopause. Menopause is when a woman no longer has her menstrual periods, and she cannot become pregnant anymore. It often starts around age 50. Perimenopause is the transition period before menopause. This period can last for several years, and the LH test can be carried out close to the end of this period
• Determine when ovulation occurs – the chances of getting pregnant are high during ovulation

The LH and FSH test has the following functions for men

• Help determine the cause of infertility
• Help determine the cause of low sex drive
• Determine the cause of a low sperm count

In children, these tests are usually for diagnosing delayed or early puberty.

• Puberty is early if it starts before age 10 for boys, and age nine for girls
• Puberty is delayed if it hasn’t started when a boy is 14 years or a girl is 13 years

Why is the LH test necessary?

If you are a woman, you may need this test in the following cases.

• You aren’t able to get pregnant after 12 months of trying
• Your periods have stopped – this test can help find out if you are in perimenopause or have gone through menopause

You may need this test in the following situations if you are a man

• You have a reduced sex drive
• You haven’t been able to get your partner pregnant after 12 months of trying

Men and women will need the LH test if symptoms of a pituitary disorder occur. These symptoms include

• Weight loss
• Weakness
• Decreased appetite
• Fatigue

A child may need the LH test if puberty doesn’t start at the right age, either too late or early.

What happens during an LH test?

The healthcare professional will draw your blood sample from a vein in your arm with a small needle. After inserting the needle, the professional will collect a small amount of blood into a vial or tube. The needle entering inside or out of your hand may cause a slight sting. This procedure takes less than five minutes.

Do I need to prepare for the test?

For women, the healthcare professional may schedule the test at a specific time during the menstrual cycle.

Does the test have any risk?

A blood test has a minimal risk. The blood draw may cause slight pain or bruising where the provider inserted the needle, but the symptoms clear quickly.

What does the result mean?

The result’s meaning often depends on if you are a child, man, or woman.

For women, high LH levels may mean the following.

• You aren’t ovulating – if you are within childbearing age, your ovaries have an issue. For older women, it means menopause has started or perimenopause
• You have polycystic ovary syndrome (PCOS) – a common hormone disorder in children of childbearing age. It is one of the most common causes of female infertility
• You have Turner syndrome – this is a genetic disorder affecting sexual development in females and usually causes infertility

For women, low LH levels may indicate

• You are malnourished
• You have an eating disorder
• Your pituitary gland isn’t functioning correctly

For men, elevated LH levels may indicate

• You have Klinefelter’s syndrome – a genetic disorder affecting sexual development in males. It usually causes infertility
• Your testicles are damaged due to radiation, infection, alcohol abuse or chemotherapy

For men, low LH levels may indicate pituitary gland or hypothalamus disorder. The hypothalamus is a part of the brain that controls vital body functions and the pituitary gland.

In children, elevated LH and FSH hormones may indicate the onset of puberty or puberty has already started. If this occurs before age nine in a girl or age ten in a boy, it may signify

• A brain injury
• A central nervous system disorder

Low LH and FSH levels in children may be a sign of delayed puberty, which often results from

• An eating disorder
• Turner syndrome in girls
• An infection
• Klinefelter’s syndrome in boys
• A hormone deficiency
• A disorder of the testicles or ovaries

Other facts about the LH test

An at-home test for measuring LH levels with urine is available. The kit helps detect the rise in LH levels before ovulation. It can help determine when you will be ovulating, which has the best chance of getting pregnant, but this test isn’t reliable if you want to prevent pregnancy.

If you want to undergo an LH blood test, visit our clinic at Suite E, 117a Harley St, Marylebone, London W1G 6AT. You can also call us on 02071830244 to book an appointment for your LH test or to get more information on our test.