Luteinising Hormone: What do Your LH Levels Mean?

Luteinising hormone (LH) is one of the key hormones involved in the regulation of the menstrual cycle and ovulation. But what happens when our levels get a little off balance? In this article, we’ll explain exactly what luteinising hormone is, how it works, and take a deep dive into its importance for female fertility. We’ll also take a look at LH levels and why they’re important, as well as how to recognise the symptoms of low or high LH.

Quick facts:

• LH helps to regulate the menstrual cycle and trigger ovulation.
• Some people with PMOS (formerly PCOS) have higher baseline LH, but high LH alone does not diagnose PMOS.
• Low LH can sometimes occur when signalling between the hypothalamus, pituitary gland and ovaries is reduced, including with low energy availability or hypothalamic amenorrhoea.

What is Luteinising Hormone (LH)? 

Luteinising hormone is a hormone made by the pituitary gland in the brain. It forms part of a communication system between your brain and reproductive organs known as the hypothalamic-pituitary-gonadal axis (HPG axis).

The hypothalamus (also in the brain) makes gonadotrophin-releasing hormone (GnRH), which tells the pituitary gland to make two key reproductive hormones: luteinising hormone (LH) and 

LH and, follicle-stimulating hormone (FSH). These two hormones work closely together. FSH helps the follicles (the small sacs in your ovaries containing immature eggs) develop during the first half of the menstrual cycle. LH then becomes particularly important around the middle of the cycle, when a sharp rise in LH helps trigger ovulation, the release of a mature egg from the ovary.

What does luteinising hormone do during the menstrual cycle?

Luteinising hormone (LH) works alongside FSH and oestradiol to coordinate the menstrual cycle and regulate ovulation.

At the beginning of the cycle, LH levels are relatively low. During this follicular phase, FSH helps several follicles (the sacs with the immature eggs) begin developing. As one follicle becomes dominant, it produces increasing amounts of oestradiol.

The rise in oestradiol tells your pituitary gland to stop making FSH and to start making more LH. This is known as the LH surge. The LH surge helps the egg complete its final maturation and triggers the dominant follicle to rupture, releasing the egg from the ovary. This process is called ovulation.

After ovulation, LH levels fall as the cycle enters the luteal phase. LH helps the emptied follicle develop into the corpus luteum, which produces progesterone alongside oestradiol. These hormones help prepare and maintain the uterine lining in case pregnancy occurs.

If pregnancy doesn’t occur, the corpus luteum eventually breaks down. Progesterone and oestradiol levels fall, your period begins and the cycle starts again.

You can read more about how all of these hormones work together in our Menstrual Cycle 101 guide.

What is the LH surge?

The LH surge is a rapid rise in luteinising hormone that happens shortly before ovulation.

This is exactly what at home ovulation predictor kits, or OPKs, are designed to detect.

Urinary LH tests can identify the mid-cycle surge that generally occurs around 24-36 hours before ovulation, which is why they can be useful for identifying when your fertile window may be approaching.

But an LH surge predicts that ovulation may happen. It doesn’t prove that an egg was actually released.

How does luteinising hormone affect fertility?

LH is essential for fertility because it helps coordinate ovulation. Without appropriate LH signalling, the final stages of follicle maturation and egg release may not happen.

But this doesn’t mean a single LH result can tell you whether you are fertile. Fertility depends on many factors, including your age, whether you’re ovulating, ovarian reserve, fallopian-tube and uterus health, sperm health and whether underlying health conditions such as endometriosis or PMOS are present.

LH is therefore usually interpreted as one part of the fertility picture.

Current NICE guidance recommends measuring FSH and LH in people with irregular menstrual cycles who are undergoing fertility investigation, helping doctors understand whether disrupted ovulation may be part of the problem.

If you’re tracking ovulation at home, LH can also help identify when your fertile window may be approaching, although, again, it can’t confirm ovulation by itself.

Why do I need an LH test?

An LH test can be useful for several different reasons. One of the most common is investigating irregular or absent periods. Because LH is involved in ovulation, looking at it alongside hormones such as FSH and oestradiol can give clues about how the communication between your brain and ovaries is working.

LH may also be measured if you’re having difficulty conceiving, particularly if your cycles are irregular or there is reason to think you might not be ovulating consistently. It can also form part of the investigation of conditions such as PMOS, hypothalamic amenorrhoea, primary ovarian insufficiency or pituitary disorders, although LH cannot diagnose any of these conditions on its own.

For example, lower LH and FSH alongside low oestradiol can point towards reduced signalling from the hypothalamus or pituitary gland, while raised gonadotrophins alongside low ovarian hormone levels can suggest reduced ovarian function.

LH testing is therefore most useful when it is interpreted alongside your symptoms, menstrual-cycle pattern and other hormone results.

How can I find out my LH level?

LH can be measured through a blood test or, for ovulation tracking, through a urine test.

A blood test measures the amount of LH circulating in your bloodstream. This is usually the more useful approach when LH is being investigated as part of a wider hormone assessment.

Urinary ovulation tests have a different purpose. They’re designed specifically to detect the rise in LH that happens shortly before ovulation.

Standard OPKs generally show a positive or negative result once LH passes a particular threshold, while some digital or quantitative monitors show more information about changing urinary LH levels.

Can an LH test tell you if you’re ovulating?

An LH blood test can measure how much LH is circulating at one moment in time. An ovulation predictor kit measures LH in urine and looks for the surge that usually happens before ovulation. A positive ovulation test therefore suggests that ovulation may be approaching.

But LH testing doesn’t directly confirm that an egg was released. For clinical confirmation of ovulation, mid-luteal progesterone is generally more useful.

If you have PMOS and are using LH strips, interpretation can be trickier because some people have higher baseline LH or more than one apparent rise during a cycle.

We cover this in much more detail in our guide to how to track ovulation with PMOS (PCOS).

When should I take an LH test?

The best time depends on why you’re testing. If LH is being measured as part of a baseline reproductive-hormone assessment, it is usually checked during the early follicular phase, near the beginning of your menstrual cycle.

At Hertility, cycling hormones such as LH, FSH and oestradiol are generally tested around cycle day 3, because that’s when they can be compared with the appropriate early-cycle reference ranges. If your cycles are shorter than 21 days, Hertility recommends testing on day 2 instead.

If your cycles are very irregular, Hertility generally recommends waiting for a period where possible. With cycles longer than 45 days, you can test on another day rather than waiting indefinitely, although the results may need more careful interpretation.

If you’re using an LH urine test to predict ovulation, the timing is completely different. These tests are used around your expected fertile window and repeated over several days to try to identify the LH surge.

What are normal LH levels in women?

There isn’t one universal normal LH level. That’s because LH naturally changes depending on your menstrual-cycle phase, age, menopausal status, hormonal medication and the laboratory method being used.

LH is usually relatively low during the early follicular phase, rises sharply around ovulation and then falls again during the luteal phase. As a result, LH and FSH can fluctuate substantially from one day or cycle to the next. 

As you approach menopause, LH starts increasing because the ovaries produce much less oestrogen and progesterone. The pituitary responds to this reduced ovarian feedback by increasing the production of gonadotrophins, including LH and FSH.

During early pregnancy, LH levels remain low, blocked by continued progesterone production. High levels of human chorionic gonadotropin (hCG) released throughout pregnancy also ensure that they stay low throughout pregnancy, so no further ovulation is triggered.

That’s why it’s much more useful to interpret your result against the appropriate reference range for your cycle phase and circumstances than to search online for one ideal LH number.

What does a high LH level mean?

A high LH result does not automatically mean something is wrong. A high LH result around the middle of your cycle may simply reflect the normal LH surge before ovulation. Persistently or unexpectedly raised LH outside the mid-cycle surge can sometimes be seen in other situations.

PMOS (formerly PCOS)

Some people with polyendocrine metabolic ovarian syndrome (PMOS, previously PCOS) have higher LH levels. This is thought to relate to changes in signalling between the hypothalamus, pituitary gland and ovaries. But not everyone with PMOS has raised LH.

And importantly, a high LH result does not diagnose PMOS. Diagnosis is based on a combination of ovulatory dysfunction, hyperandrogenism and, where needed, ovarian morphology assessed by ultrasound or AMH.

You may also have heard that an LH ratio of 2:1 or 3:1 proves you have PCOS. It doesn’t. An increased LH ratio can occur in some people with PMOS, but it is not part of the diagnostic criteria and shouldn’t be used by itself to diagnose the condition. 

Read our complete guide to PMOS (PCOS) for more on symptoms, diagnosis and treatment.

Primary ovarian insufficiency and reduced ovarian function

Higher gonadotrophin levels can also occur when the ovaries are not responding normally to signals from the pituitary gland. One example is primary ovarian insufficiency (POI), where ovarian function becomes impaired before the age of 40.

POI diagnosis relies much more heavily on FSH and menstrual history than on LH alone, so an elevated LH result would need to be interpreted alongside FSH, oestradiol, symptoms and your wider clinical history.

Perimenopause and menopause

LH levels also rise naturally as ovarian hormone production falls during the menopausal transition and after menopause. But for otherwise healthy people aged 45 or over with typical menopause symptoms, NICE recommends diagnosing perimenopause or menopause primarily from symptoms rather than using routine hormone testing.

Turner syndrome

Turner syndrome is a genetic condition involving one of the X chromosomes and can affect ovarian development and function. Where ovarian function is reduced, the ovaries produce less oestrogen. The brain responds by producing more gonadotrophins, so both FSH and LH can become elevated. LH is not used alone to diagnose Turner syndrome, but it can form part of the broader endocrine pattern.

Pituitary conditions

Because LH is made by the pituitary gland, pituitary disorders can occasionally affect LH secretion. Rare tumours called gonadotroph adenomas arise from the pituitary cells involved in producing FSH and LH. Most do not cause isolated LH excess, so this is a much less common explanation for a raised LH result than normal cycle variation, menopause or changes in ovarian function.

If there are additional symptoms suggesting pituitary disease, such as persistent severe headaches, visual changes or abnormalities across several pituitary hormones, further investigation may be needed.

What are the Symptoms of High LH Levels?

High LH itself usually doesn’t produce a distinctive set of symptoms. Instead, symptoms tend to come from whatever is causing the hormonal pattern.

For example, if LH is raised because ovarian function is reduced, associated low oestrogen may contribute to irregular or absent periods, hot flushes, night sweats, vaginal dryness or changes in libido. If higher LH forms part of a PMOS hormone pattern, symptoms might instead include irregular cycles, acne or excess facial or body hair.

Can you lower high LH levels?

Usually, the aim isn’t to lower LH itself, the treatment depends on why the level is high.

If LH is high because you’re approaching ovulation, nothing needs treating. If it’s higher because of menopause, that’s part of the normal physiological response to lower ovarian hormone production. And if an abnormal pattern is related to PMOS, POI or another condition, treatment focuses on the underlying condition and your symptoms rather than trying to manipulate LH directly.

What does a low LH level mean?

Again, a low result only makes sense in context. LH is meant to be relatively low during much of the menstrual cycle, so a result near the bottom of a reference range isn’t automatically concerning. However, low LH alongside low FSH and low oestradiol may sometimes suggest reduced signalling from the hypothalamus or pituitary gland.

One possible cause is functional hypothalamic amenorrhoea. This happens when signalling from the hypothalamus slows down, reducing GnRH pulses and, in turn, the release of LH and FSH.

One important trigger is low energy availability, when the energy your body receives through food isn’t enough to cover both exercise and essential physiological functions. This can occur with restrictive eating, significant weight loss or high exercise loads without adequate fuelling. The result can be disrupted ovulation and irregular or absent periods. Importantly, you do not need to be underweight for low energy availability to affect reproductive function.

Conditions affecting the hypothalamus or pituitary gland can also reduce LH and FSH production. This is called hypogonadotropic hypogonadism. Possible causes range from functional suppression of the reproductive axis to rarer structural, inflammatory or genetic conditions.

Current guidance for hypogonadotropic hypogonadism and functional hypothalamic amenorrhoea focuses on restoring adequate energy availability and moderating excessive exercise where relevant.

One example is Kallmann syndrome, a rare congenital condition affecting GnRH signalling. Rare genetic changes affecting LH itself or its receptor can also interfere with LH production or action, although these are uncommon and generally only investigated when the wider clinical picture suggests a congenital reproductive-hormone disorder.

Can stress cause low LH?

It’s more complicated than saying stress lowers LH. Your reproductive system is sensitive to your overall physiological environment. Significant physical or psychological stress can influence signalling between the hypothalamus and pituitary gland, particularly when it happens alongside factors such as under-fuelling, weight change, illness or intense exercise.

But persistent low LH or absent periods shouldn’t simply be blamed on stress without investigating other possible causes. If your periods have stopped or changed significantly, it’s worth speaking to a healthcare professional rather than assuming you just need to “stress less”.

What are the symptoms of low LH? 

As with high LH, low LH itself doesn’t necessarily cause symptoms. Problems occur when reduced LH and FSH signalling leads to reduced ovarian hormone production and disrupted ovulation.

Depending on the underlying cause, this may show up as irregular or absent periods, difficulty conceiving or delayed puberty. If oestrogen remains low for a prolonged period, symptoms can include vaginal dryness or changes in libido, and long-term low oestrogen can also affect bone health.

Fatigue and mood changes can occur alongside some of these conditions, but they are non-specific and shouldn’t automatically be blamed on a low LH result.

Can you increase low LH levels naturally?

Again, the goal usually isn’t to increase LH for its own sake. If LH is genuinely low, treatment focuses on what is causing it.

For functional hypothalamic amenorrhoea related to low energy availability, that may mean increasing energy intake, improving nutritional adequacy and/or reducing excessive exercise. Psychological support can also be useful where stress, anxiety or disordered eating contributes.

If low gonadotrophins are caused by another medical or pituitary condition, treatment is directed at that underlying problem.

And if pregnancy is the goal and ovulation doesn’t recover, fertility specialists can use treatments such as gonadotrophins with LH activity or GnRH therapy in appropriate cases of hypogonadotropic hypogonadism. 

How does hormonal contraception affect LH?

Hormonal contraception can significantly alter LH. Methods such as the combined contraceptive pill suppress the hormonal signals involved in follicle development and ovulation, which changes LH, FSH and oestradiol levels.

That means testing these cycling hormones while using hormonal contraception often doesn’t provide the same information as measuring your natural cycle.

Hertility therefore does not routinely include LH, FSH or oestradiol in personalised panels for people currently using hormonal contraception or HRT, because those results are directly influenced by the hormones being taken. Other biomarkers can still be useful depending on your individual circumstances.

How Hertility can help you understand your LH

If your periods are irregular, you’re struggling to understand whether you’re ovulating or you simply want a clearer picture of your hormone health, Hertility can help you look beyond one result.

Our Advanced Hormone & Fertility Test can assess a personalised panel of up to 10 hormones, including LH where clinically appropriate. 

LH is then interpreted alongside your menstrual cycle, symptoms, health history and other hormone results. Your Advanced Test also comes with a doctor-written report, personalised care plan and a Clinical Results Review Call, so you can understand what your results mean and whether anything needs further investigation.

Not sure whether LH is actually relevant to what you’re experiencing? Start with Hertility’s Online Health Assessment, which personalises the next steps according to your symptoms, cycle and health history.

If you’ve already done a test and received an abnormal LH result, you can book an appointment with one of our Private Gynaecologists specialising in hormone and fertility concerns to discuss your results and get a personalised care plan. Appointments are available daily, with no GP referral required.

Frequently Asked Questions

What does luteinising hormone do?

LH is made by the pituitary gland and helps regulate reproductive function. During the menstrual cycle, the mid-cycle LH surge triggers ovulation. LH also supports the corpus luteum after ovulation.

What does high LH mean?

It depends on when the test was taken. LH normally rises dramatically before ovulation and is also higher after menopause. Unexpectedly high LH outside these situations can sometimes occur with conditions affecting ovarian function, including PMOS and primary ovarian insufficiency, but LH alone cannot diagnose these conditions.

What does low LH mean?

Low LH can be normal during parts of the menstrual cycle. Persistently low LH alongside other hormone changes may sometimes indicate reduced hypothalamic or pituitary signalling, including conditions such as hypothalamic amenorrhoea.

What is a normal LH level for a woman?

There is no single normal LH value. Expected levels vary according to menstrual-cycle phase, age, menopausal status, medication and the laboratory method being used.

When is LH highest?

During a typical menstrual cycle, LH rises sharply just before ovulation. This is known as the LH surge.

Does high LH mean I have PCOS or PMOS?

No. Some people with PMOS have raised LH, but many do not. LH is not one of the diagnostic criteria and a high result should not be used by itself to diagnose PMOS.

Is the LH ratio used to diagnose PCOS?

No. An increased LH ratio may be seen in some people with PMOS, but there is no diagnostic ratio and it is not part of the current diagnostic criteria.

Does an LH surge mean I definitely ovulated?

No. An LH surge predicts that ovulation is likely to occur, but it does not confirm that an egg was released. Correctly timed progesterone testing can provide stronger evidence that ovulation actually occurred.

When should I test my LH?

It depends on why you’re testing. For a baseline hormone assessment, LH is often measured during the early follicular phase. Hertility generally recommends cycle day 3 for cycling hormones in people with periods who aren’t using hormonal contraception.

Can you test LH while on the pill?

You can measure it, but hormonal contraception suppresses and alters reproductive-hormone signalling, making the result less useful for assessing your natural cycle. Hertility therefore does not include LH in its personalised testing panel while someone is using hormonal contraception or HRT.

Does LH increase during menopause?

Yes. LH generally rises as ovarian hormone production falls. However, routine hormone testing is not usually needed to diagnose perimenopause or menopause in otherwise healthy people aged 45 or over with typical symptoms.

Resources

• Luteinizing hormone and its dilemma in ovulation induction. 
• The Normal Menstrual Cycle and the Control of Ovulation 
• Physiology, Luteinizing Hormone – StatPearls – NCBI Bookshelf 
• Onset of the preovulatory luteinizing hormone surge: diurnal timing and critical follicular prerequisites 
• Stimulatory and inhibitory effects of progesterone on FSH secretion by the anterior pituitary 
• Primary ovarian insufficiency: an update 
• Idiopathic primary ovarian insufficiency: a study of serial hormonal profiles to assess ovarian follicular activity
• FSH may be a useful tool to allow early diagnosis of Turner syndrome
• Follicle Stimulating Hormone (LH: FSH) Ratio in Polycystic Ovary Syndrome (PCOS) – Obese vs. Non- Obese Women 
• Relationship of GnRH‐stimulated LH release to episodic LH secretion and baseline endocrine‐metabolic measures in women with polycystic ovary syndrome 
• Ovarian function and cigarette smoking in the BioCycle Study 
• Effects of soy foods on ovarian function in premenopausal women 
• Effects of soy foods on ovarian function in premenopausal women 
• Obstetric and gynecologic problems associated with eating disorders 
• Eating disorders from a gynecologic and endocrinologic view: hormonal changes 
• A review of the pathophysiology of functional hypothalamic amenorrhoea in women subject to psychological stress, disordered eating, excessive exercise or a combination of these factors 
• Effect of Exercise on Ovulation: A Systematic Review 
• Effects of metformin administration on plasma gonadotropin levels in women with infertility, with an in vitro study of the direct effects on the pituitary gonadotrophs. – Abstract 
• Glucocorticoids, Stress, and FertilityMarihuana S