Luteinising hormone is an important cycling hormone, 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: What is Luteinising Hormone (LH)?  Luteinising hormone (LH) plays a huge role when it comes to fertility and ovulation, despite it being one of the lesser-known cycling hormones. Luteinising hormone (LH) is what’s known as a gonadotropin hormone. There are only two types of this hormone, LH and its partner in crime, follicle-stimulating hormone (FSH). Gonadotropins are hormones that are released from the pituitary gland in the brain, into the bloodstream where they are transported to the gonads—or ovaries in those assigned female-at-birth and the testes in those assigned male-at-birth. LH has 3 main functions in those assigned-female-at-birth:  Oestrogen production LH works in tandem with FSH to stimulate the ovaries and surrounding cells to produce oestrogen. First, LH stimulates what’s known as theca cells in the ovaries, which then produce testosterone. Once testosterone is abundant, nearby granulosa cells are then stimulated by FSH to produce an enzyme called aromatase, which converts the testosterone into a type of oestrogen, oestradiol, or E2. Without the correct functioning of LH or FSH, testosterone and oestrogen production can become impacted. Ovulation LH is also crucial for successful ovulation. First, FSH stimulates the growth of follicles (small sacs that contain your eggs) in your ovaries. A number of eggs mature during the first half of your cycle, but only one gets released during ovulation—usually the ‘most mature’ follicle. In the days leading up to ovulation, this follicle increases its sensitivity to LH. It gradually produces more and more E2 and when this reaches a certain level, the pituitary gland releases a surge of LH. This LH surge is what causes the follicle to rupture and release the mature egg into the fallopian tube—triggering ovulation. Progesterone production After ovulation has occurred, LH stimulates the now empty follicle to start producing progesterone throughout the second half of the menstrual cycle—also known as the luteal phase. Both progesterone and E2 released by the empty follicle are intended to support conception, implantation and the early stages of pregnancy. However, if the egg is not fertilised and no embryo implants into the uterus, the empty follicle stops producing these hormones and eventually wastes away at the end of the menstrual cycle. What are normal LH levels in women? LH levels in women, or those assigned-female-at-birth, fluctuate during the menstrual cycle—so their levels will vary depending on where you are in your monthly cycle. LH levels can also vary depending on an individual’s age and whether they’re pregnant. Normal LH levels for women before menopause are around 5-25 IU/L, depending on the stage of the menstrual cycle. After menopause, normal LH levels range from around 14-52 IU/L. LH levels during the menstrual cycle Let’s take a closer look at how LH fluctuates during the menstrual cycle. As we mentioned earlier, a dramatic surge in LH around the middle of the cycle triggers ovulation. But after ovulation, LH production is dulled by rising levels of progesterone. If no pregnancy occurs and progesterone levels fall, LH production will start again anew at the beginning of the next cycle. LH levels during pregnancy 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. LH levels in menopause During menopause, LH levels become elevated, although this can vary from person to person. This increase in LH levels happen as a result of the general decline in hormone production by the ovaries. When the ovaries stop producing as much oestrogen and progesterone, the pituitary responds by increasing the production of FSH and LH, in an attempt to stimulate the ovaries. However, the ovaries become less responsive and, instead, LH levels rise. This rise in LH levels is associated with a lot of the typical symptoms of menopause, including hot flashes and night sweats. After menopause, LH levels can decline by around 30-40%. High LH levels High LH levels in females outside of normal menstrual cycle fluctuations can cause fertility problems, irregular periods and early puberty. High LH levels are often seen in people with primary ovarian insufficiency and in those with polycystic ovary syndrome (PCOS) often have elevated LH compared to their FSH. This unusual imbalance can lead to irregular periods and the overproduction of testosterone, both key symptoms of PCOS. Sometimes LH levels can become elevated due to dietary and lifestyle factors, including: Symptoms of high LH levels Symptoms of high LH levels in females are more related to the underlying cause than the LH itself. However, some of the most common symptoms associated with the causes of high LH levels include: How to lower LH levels If your LH levels are elevated and you are a regular smoker or drinker, consider taking steps to reduce these habits. If you’re trying to conceive, consider cutting alcohol and cigarettes completely as this will improve your chances of conception and prevent harmful effects to the baby during pregnancy. Low LH levels There are also a number of reasons why low LH levels might occur. Meningitis infections that have occurred in the last 12 months have been linked to low LH levels and so have eating disorders. Sometimes, LH levels can be decreased due to dietary and lifestyle factors as well as certain medications including: Low LH levels in females can lead to problems with ovulation. This includes anovulation, which is not ovulating at all. This can also lead to problems with menstruation, such as irregular, missing, or complete cessation of periods. Symptoms […]

Follicle-stimulating hormone (FSH) is really important for our reproductive health. In this article, find out how to know what normal FSH levels look like, what the symptoms of high and low FSH levels are and how to balance your FSH levels. Quick facts: What is FSH?  FSH stands for Follicle-Stimulating Hormone and is one of the main hormones involved in the regulation of your menstrual cycle and ovulation—making it an important hormone not only for your health but your fertility too. FSH is what’s known as a gonadotropin hormone. It’s released by the pituitary gland in the brain and then acts on the ovaries.There is only one other gonadotropin hormone in the body—luteinising hormone (LH). True partners in crime, there’s no FSH without LH, and they act in tandem to bring about changes which essentially regulate ovulation. Normal FSH levels in women Because our FSH levels are intricately linked to our ovarian reserve, what’s considered a ‘normal’ FSH level changes as we age. This is because our ovarian reserve declines as we age which makes our FSH levels increase.  Gonadotropic hormones are hormones released from the pituitary gland in the brain and released into the bloodstream. Gonadotropins then go on to act on the ovaries. There are two types of gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH).  The pituitary gland produces FSH which acts on the ovaries to stimulate the growth of follicles containing your eggs. As well as growing the ovarian follicles, FSH stimulates the granulosa cells that surround the follicle to produce oestrogen from testosterone, an essential hormone for regulating the menstrual cycle (1). You can read more about oestrogen here.  What does FSH do? FSH has two primary functions:  Follicular development FSH does pretty much exactly what it says on the tin—it stimulates the growth of follicles which contain your eggs.  You’re born with ‘immature’ eggs. So each month, a number of them start maturing before one is released during ovulation. Your eggs are housed in tiny follicles inside your ovaries, and it’s these follicles that FSH signals to prepare your eggs for ovulation (2). Oestrogen production FSH also stimulates the cells that surround the follicles to make an enzyme called aromatse, which converts testosterone into oestrogen, another essential hormone for regulating the menstrual cycle and reproductive health (1). The relationship between FSH and LH When your eggs are fully mature and ready to be released during ovulation, LH steps in. A surge of LH is released, again by the pituitary gland in the brain, causing the most mature follicle to rupture—releasing an egg into your Fallopian tube. This is ovulation.  Despite FSH causing numerous follicles, and therefore numerous eggs, to mature each cycle, only one follicle will release an egg each month. This is because FSH and LH are both involved in negative feedback loops, controlled by E2. But what does negative feedback loop mean? Increasing FSH levels in the early stages of your menstrual cycle leads to more oestrogen being made, but this ha, a negative feedback effect on FSH levels. In other words, when you have lots of oestrogen, it feeds back to the brain that it needs to stop making more FSH. Similarly, with LH, oestrogen levels keep increasing through the cycle and once they reach a peak around the middle of the cycle, it causes a sudden surge in LH that promotes ovulation. After ovulation, the empty follicle that once contained the egg makes another hormone, progesterone, to support conception, implantation and the early stages of pregnancy. High levels of progesterone tell the brain to stop making more FSH. Now if a pregnancy doesn’t happen, there is a drop in oestrogen and progesterone which triggers your period. It also tells the brain it needs to start making FSH to start the whole process all over again in the next menstrual cycle (5). High FSH levels Okay, but what happens when we have high FSH levels? Let’s take a look at the causes and symptoms of high FSH levels. What causes high FSH levels? The most common reason for high FSH levels is a low ovarian reserve (egg count), or ovaries that aren’t functioning properly. When we have a low ovarian reserve, this essentially means we have a smaller number of immature follicles available in our ovaries and our bodies will produce less oestrogen.  Because oestrogen controls how much FSH we produce (remember that negative feedback loop), when we have less oestrogen, our FSH levels may go up.  High FSH levels can therefore indicate that our ovaries aren’t functioning properly, be an indicator of low ovarian reserve or an indicator of the onset of menopause. Other reasons for high FSH levels can be ovarian cancer (although this is very rare) (9) and Premature Ovarian Insufficiency (POI) which is the loss of ovarian function before the age of 40 (6,7). In some cases, dietary and lifestyle factors can moderately raise FSH levels. Symptoms of high FSH levels Symptoms of high FSH levels usually mimic symptoms of menopause and are related to low oestradiol levels —which is why it’s so important to test a range of your reproductive hormones to get to the bottom of symptoms. Symptoms can include: How to lower FSH levels? It is important to understand that if high FSH levels have been caused by menopause or a low egg reserve, modifications to your diet or lifestyle will not be able to reverse this. However, there are some dietary lifestyle factors associated with a higher FSH, such as smoking and high alcohol consumption.  If you’re trying to conceive, consider cutting alcohol and cigarettes completely as this will improve your chances of conception and prevent harmful effects to the baby during pregnancy (17). For advice on how to quit smoking, see the full list of NHS quit smoking services here. Nutrition can be a really powerful tool in balancing hormones and helping to alleviate symptoms. You can book a nutritional health consultation with one of our registered nutritionists via your health hub. […]