Luteinizing hormone: Levels, function and tests

What is luteinizing hormone?

LH is a natural chemical that’s found in our bodies. It plays an important role in both male and female reproductive health. Testing for LH, either through taking a blood or urine sample can reveal important information about your fertility. [1]

What does luteinizing hormone do?

Hormones work as messengers, and LH is no different. It’s responsible for a number of factors connected to our reproductive health, including regulating certain processes during the menstrual cycle in females, and is important for healthy sperm development in males. [1]

Luteinizing hormone function in women

LH plays a key role in puberty by stimulating the ovaries to produce sex hormones, such as testosterone and estrogen, which are responsible for the development of reproductive organs, growth of pubic hair, and other changes that occur as we reach sexual maturity [2]

For those of us who menstruate, LH varies throughout the cycle. It’s connected to another female sex hormone, estrogen[1]. The two work together along with a bunch of other hormones, to co-ordinate and regulate the phases of the menstrual cycle. LH is crucial when it comes to the release of a female egg cell. [1] This happens at ovulation (around the mid-point of the cycle), and it’s even possible to detect a surge in LH levels with at-home ovulation tests. The LH surge usually occurs in about 1-2 days before ovulation in most women. [3]

LH also plays a role in helping with implantation of a fertilized egg cell which is a key stage in early pregnancy. [4]

In older women, consistently elevated LH levels can also be a sign of menopause, when the menstrual cycle stops altogether. [5]

Luteinizing hormone function in men

While LH is often associated with female fertility, this hormone plays an important role in male fertility too. LH is essential for the production of testosterone — the main male sex hormone — this is important for the physical developments that happen during puberty, but also essential for ongoing sperm production. [1]

Unlike adult females, adult males experience more steady LH levels, these don’t tend to fluctuate as much as fertility remains constant in healthy adult males. [6] This is different to adult females who are only fertile for a limited number of days during the menstrual cycle and cannot conceive after menopause. That said, recent research suggests that while mean LH levels do not significantly change with age, the way this hormone is produced does become more irregular and asynchronous in older men. The study indicates that these irregularities might play a role in age-related declines in male reproductive health. [7]

Where is LH found?

We’ve talked a lot about the reproductive organs, but LH is actually produced by the pituitary gland, a small but crucial organ that’s found in your brain. Once LH is produced it travels around the body and signals to the sex organs (testes and ovaries) to kickstart the various processes that are needed for reproduction.[1]

How to test for LH levels? 

Now you know what LH is, what it does, and where to find it… but how do you test for it? There are two ways to test for LH: by analyzing a sample of blood or urine. The type of test you take will depend on your needs. 

Why test for LH in female fertility?

If you’ve had trouble trying to conceive, your doctor may want to test LH levels in your blood to rule out any fertility problems. [6]

If you’re at the start of your journey in planning pregnancy, or simply want to learn more about your own fertility, you can test for LH at home using ovulation tests. These analyze levels of LH in urine and are quick and easy to use.

As LH varies throughout the cycle you should expect to see varying levels depending on when you test. Elevated LH levels throughout the cycle may be a sign that you are in perimenopause. [5] Understanding LH levels can also help diagnose or rule out conditions such as PCOS (polycystic ovary syndrome), particularly when other symptoms are taken into account. [8]

What are LH tests used for in male fertility?

In males, a blood test can be used to determine if LH levels are unusually high or low, as this can impact fertility. Unusually elevated levels of LH alongside lower testosterone levels can indicate that the testicles aren’t responding to the LH’s signal to produce more testosterone. On the other hand, lower LH levels may indicate that the pituitary gland isn’t producing enough LH, this can also cause a lower level of testosterone production. [6]

Testosterone plays an important role in healthy sperm production, so understanding its relation to LH levels is an important factor in ruling out male fertility issues.

What is a normal luteinizing hormone level?

This depends on who you are and what life stage you’re at. LH levels vary for women depending on the different parts of the cycle, adult males should expect to see less fluctuations in the LH level. Here’s a breakdown of LH units of what’s considered normal for men, and women at different points of their reproductive journey:

Normal LH result for males: 

• 1 - 8 IU/L

Normal LH results for females: 

• Follicular phase:1 – 12 IU/L
• Around ovulation: 16 – 104 IU/L
• Luteal phase (post ovulation): 1 - 12 IU/L
• Post-menopausal: 16 – 66 IU/mL

Measurements are given in international units per milliliter (IU/L). [9] Normal ranges may vary depending on the guidelines of the laboratory carrying out the analysis. 

What happens when luteinizing hormone levels are low?

In males, low LH levels are linked to reduced testosterone production, which can in turn inhibit sperm production and lead to other symptoms such as erectile dysfunction. [1]

In terms of female fertility, lower LH levels are normal during the first phase of the menstrual cycle. However, a consistently lower LH level can be a sign that there is a hormonal imbalance, the pituitary gland isn’t producing enough LH or the LH levels are impacted by another disorder. [10] This can inhibit key stages in the cycle such as ovulation, or make it more difficult for a fertilized egg cell to implant.

What does high LH mean? 

At the same time, elevated LH can also be connected to fertility issues. Consistently high levels of LH can a sign a woman is perimenopausal or has reached menopause. Menopause is defined as 12 months of not having a period. However, it’s still possible to get pregnant during the years of perimenopause (the phase before menopause) if you are still ovulating. 

Conceiving and keeping a pregnancy is likely to be more difficult for those going through perimenopause, mainly due to the quality and the quantity of the eggs that remain in the female body, and the risk of pregnancy loss also increases with age. However, some are able to successfully conceive during this time. [11,12] 

Increased LH levels can also be connected to PCOS — which is shown to affect cycle length and regularity. [13] Keep in mind it’s still possible to get pregnant for those with PCOS, but it might take longer as cycles can be more unpredictable. 

The first step is to talk to your doctor, they will be able to help you understand what’s happening in your body and the steps you can take to tackle any hormonal imbalances.

What foods increase luteinizing hormone?

Maintaining a healthy lifestyle (including a well-balanced diet) is important for hormonal health. However, while some research has been conducted into the relationship between a high-fiber diet and low LH, there is currently limited evidence to suggest that specific foods can increase LH levels or change luteinizing hormone function. [14]

If you are planning pregnancy, you may find it helpful to read up on our guide of what to eat while pregnant. Making changes to your diet ahead of pregnancy can help you prepare for the journey ahead. 

What happens during an LH levels test?

If you require a blood test, this can be carried out quickly in a couple of minutes and can be done by a nurse or doctor at a clinic or hospital. Blood is taken from the arm or hand and is then sent away for processing. Depending on where you live, you should receive your results within a few days or weeks. 

It’s also possible to test for the levels of LH in the female body at home with an ovulation test. This doesn’t require the help of a medical professional, and you can read the results in just a few minutes. At-home ovulation tests analyze the presence of LH in urine. 

Depending on the test you use, you may either need to pee on the test stick or place the end of the stick into a urine sample. Always read the instructions that come with tests.

Unlike blood tests, testing LH levels at home with an ovulation test won’t tell you the specific levels of LH in your body. Instead, it can help you identify your fertile window. For most women, the LH surge typically occurs 1 to 2 days before ovulation. [15]

Digital tests will display an icon that indicates if an LH surge is detected (ovulation likely to occur) or if no surge is detected (ovulation is less likely). Strip tests are more basic tests that show two strong lines if enough LH levels are detected to confirm a surge.

These at-home tests only tell you what’s happening on one day in your cycle, and you may find you need to take tests for multiple days in order to capture the LH surge that’s associated with ovulation. 

This type of testing does not replace a consultation with a doctor or more thorough blood tests, so while it can be a useful first step to understanding your fertility, and can help you find fertile days in your cycle, you may need to talk to a healthcare professional if you have continued difficulty conceiving.

Do I need to do anything to prepare for the test?

Blood test: No specific action is required, but you may be asked to wait until a certain phase in your cycle or come for the test several days. Recording your cycle on an app or calendar will help you know what cycle day you’re on when you go for the test. 

Urine test: Follow the specific instructions that come with your ovulation tests, these may specify the best time of day to test and any other guidance you should follow. 

When to see a doctor

It’s recommended you try to conceive for at least 12 months before seeking medical advice. [16] You may want to talk to a healthcare professional sooner if you are 36 years or older or have a condition that could make it harder to get pregnant, such as PCOS. [17]

How does Natural Cycles measure LH?

Natural Cycles is a hormone-free birth control app that can also help you plan pregnancy. Based on the science of your cycle, the app’s algorithm uses temperature and period dates to work out your fertile window. However, it can also be used with ovulation tests. Measuring for an LH surge can help the NC° algorithm narrow down fertile days, meaning that those using the app as birth control don’t need to use protection on as many days, while those using it to plan pregnancy have more precise knowledge about the best time to conceive. Furthermore, the NC° app will prompt you on the best days to take ovulation tests, saving you time and money!

Freedom is taking control of your fertility

Thanks for reading up on luteinizing hormone function. Whether you’re planning pregnancy now, want kids someday, or never do, Natural Cycles is designed to empower you with the knowledge you need to take charge of your health. Choosing a hormone-free birth control today can help you plan for tomorrow, and provides a unique learning journey like no other. Get started and find out if NC° could work for you!