Luteinizing Hormone

What is luteinizing hormone?

Luteinizing hormone (LH) stimulates processes in your body that are important for puberty, sexual function, reproduction and sex drive. A tiny structure at the base of your brain called the pituitary gland secretes LH.

LH works differently in your body depending on whether you have ovaries or testes. Having too much or too little can affect how these sex organs and your entire reproductive system function.

What does luteinizing hormone do?

Think of LH as a hormone that spurs your reproductive system into action. Along with another hormone called follicle-stimulating hormone (FSH), LH helps regulate processes in your reproductive system that help your body do important things like menstruate and produce testosterone. They act as chemical messengers that signal your sex organs to start processes needed to support your reproductive health.

Luteinizing hormone in people with ovaries

LH stimulates changes in your ovaries that maintain your menstrual cycle and support pregnancy.

• Follicle development. In the first several days of your cycle, LH helps grow your ovarian follicles, which contain your eggs.
• Ovulation. A surge in LH causes your ovary to release an egg around the second week of each menstrual cycle. A high LH level around this time means that you’re at that moment in your cycle when you’re most likely to get pregnant.
• Progesterone production. LH causes a structure in your ovary called the corpus luteum to produce more progesterone during the third and fourth week of your menstrual cycle. Progesterone is a hormone that supports the early stages of pregnancy.

As you age and go through menopause, your LH levels will increase as your levels of estrogen and progesterone decrease.

Luteinizing hormone in people with testes

LH stimulates your testes to make testosterone, a hormone your body needs to produce sperm. Testosterone is also responsible for secondary sex characteristics, like a deeper voice, more body hair and increased muscle mass. LH hormone levels remain stable after puberty.

Luteinizing hormone in infants and children

During puberty, LH stimulates both ovaries and testes to make more testosterone. The ovary converts testosterone into estrogen. These hormones cause changes related to sexual development.

Where is it located?

LH gets made in the part of your body that’s responsible for regulating complex processes — your brain. But the organs that LH helps regulate are in your reproductive system.

LH is part of a complex communication network that involves your brain (hypothalamus and pituitary gland) and your sex organs (ovaries and testes). Your hypothalamus secretes a hormone called gonadotropin-releasing hormone (GnRH) that signals your pituitary gland to secrete LH. LH signals your ovaries or testes to make the hormones needed to start and maintain reproductive processes.

Understanding this communication network is important when it comes to diagnosing reproductive health issues. For example, fertility issues may involve issues with your sex hormones or hormone production in your brain. Your healthcare provider will consider multiple factors that play a role in your reproductive health when diagnosing conditions that involve LH.

What are the common conditions and disorders associated with luteinizing hormone?

LH levels fluctuate, especially with your menstrual cycle. A high or low LH level isn’t simply good or bad.

For instance, a surge in your LH can show that you’re about to ovulate. You’re most likely to become pregnant at this time. This information that LH provides about your fertility is helpful if you’re trying to have a baby.

LH levels in your body can signal problems, too. Knowing your LH level at a particular moment in time can help your provider learn:

• If you have a pituitary gland disorder
• What’s causing fertility issues
• What’s causing you to have irregular periods
• How close you are to perimenopause or menopause
• What’s causing you to have low testosterone levels

LH levels tests can also help a provider diagnose early or delayed puberty in children.

What happens when luteinizing hormone levels are high?

High LH levels can be a sign that your sex organs aren’t producing enough steroid hormones needed for a reproductive process to take place.

This happens when your ovaries or testes can no longer produce estrogen or testosterone. Genetic conditions, autoimmune conditions and trauma during surgery are all potential causes.

Turner syndrome or Fragile X in women and Klinefelter syndrome in men are examples of genetic conditions associated with high LH levels.

Polycystic ovary syndrome (PCOS) is a condition that affects women, which can cause mildly elevated LH levels. It’s a cause of irregular periods and infertility.

What happens when luteinizing hormone levels are low?

Low LH levels can mean that your pituitary gland isn’t making the LH needed to spur changes in your body that support sexual development or reproduction.

Low LH levels can be a sign of:

• Kallmann syndrome. This is a rare condition that leads to insufficient testosterone and estrogen production.
• Hypothalamic amenorrhea. This is when your period stops due to a problem with your hypothalamus. Excessive exercise, stress and poor nutrition are common causes of it.

Common tests to check luteinizing hormone levels

An LH test checks how much LH is in your blood and involves a simple blood draw. Sometimes, your healthcare provider will recommend doing an LH level test alongside an FSH test, as these hormones work together to regulate your reproductive system.

What are normal luteinizing hormone levels?

When you get your test results, remember that what’s considered normal depends on various factors, including your age, sex and medical history. The timing of your menstrual cycle or whether you’ve gone through menopause will also affect your LH levels.

The numbers below provide a general snapshot of normal LH levels. Ask your healthcare provider what your test results mean for you.

Can you get pregnant if LH is low?

Yes, you can still get pregnant if your LH level is low. LH levels can vary. You should ask your healthcare provider if your LH level is playing a role in your ability to get pregnant.

What LH level indicates pregnancy?

LH isn’t a measurement that your healthcare provider uses to confirm pregnancy. Human chorionic gonadotropin (hCG) is the hormone for that.