Luteinising Hormone: What Do Your LH Levels Mean?

October 6, 2021Bríd Ní Dhonnabháin BSc (hons), MSc

If FSH and LH sound familiar, that’s because we talk about them a lot, especially when it comes to fertility and ovulation. Here, we’re going to talk all about LH in detail. You can read more about its partner in crime, FSH here.  Let’s start with a whistle-stop tour of everything you need to know about luteinising hormone and LH levels. For more details, keep reading.

  1. What is LH?  LH is a hormone released by the pituitary gland in the brain that acts on the ovaries. 
  1. What does it do? LH plays an important role in regulating the menstrual cycle and a surge in LH at the midpoint of the cycle triggers ovulation. 
  1. How is LH regulated?  LH is regulated by other hormones, including E2 and progesterone, acting on the hypothalamus to either upregulate or downregulate LH production. 
  1. What does high LH mean and what causes it?  A high LH level is commonly seen in people with polycystic ovary syndrome (PCOS), however, it can also be caused by certain diet and lifestyle factors.
  1. What does low LH mean and what causes it?  A low LH level is commonly seen in people who have a problem with their pituitary gland, a common cause of which is stress.  A low LH level can also be caused by diet and lifestyle factors.
  1. What can I do to manage my LH?  Some changes to diet and lifestyle may help with hormone imbalances. 

What is LH? 

Gonadotropic hormones are hormones released from the pituitary gland in the brain and released into the bloodstream. Gonadotropins act on the gonads, i.e. ovaries in females and testes in males. There are two types of gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH). 

What does LH do? 

LH has a few functions: 

  • Stimulates the ovaries to produce oestrogen 
  • Causes ovulation by surging at the midpoint (roughly) of your cycle. 
  • Stimulates the empty follicle to produce progesterone after ovulation, which helps maintain a healthy pregnancy in the early weeks. 

Oestrogen production

Oestrogen isn’t directly produced by the ovaries. Instead, testosterone is produced by theca cells in the ovaries in response to stimulation from LH. At the same time, the testosterone is converted to oestrogen, more specifically a type of oestrogen, called oestradiol (E2). When the nearby granulosa cells are stimulated by FSH to produce an enzyme called aromatase which converts the testosterone into E2 (a). 


LH is crucial for successful ovulation.  In the days leading up to ovulation, the most mature follicle increases its sensitivity to LH (b). As the follicle matures, it produces more and more E2 and when this reaches a certain level, it feeds back to the pituitary gland to release a surge of LH (1). This LH causes the follicle to rupture and release the mature egg into the fallopian tube (2). 

Progesterone production 

LH plays an important role in progesterone production in the second half of the menstrual cycle, the luteal phase. During the second phase of the cycle, the luteal phase, LH stimulates the empty follicle to produce progesterone after ovulation has taken place. Progesterone and estradiol released by the empty follicle 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 wastes away at the end of the menstrual cycle (3). 

How are your LH levels regulated? 

Before ovulation, a dramatic surge in oestradiol acts on the brain to release a surge of LH to trigger ovulation (4). After ovulation, the progesterone produced by the empty follicle prevents the release of more LH from the pituitary gland. The drop in progesterone if no embryo implants allow for LH production to start again at the beginning of the next menstrual cycle (5). 

In the lead up to your period, the drop in oestradiol and progesterone is sensed by the hypothalamus in the brain which begins to produce gonadotropin-releasing hormone (GnRH), which travels to the pituitary to produce gonadotropins FSH and LH.

What does high LH mean and what causes it? 

Too much LH can cause fertility problems. Baseline levels of LH rise after menopause and therefore high LH levels are seen in people with primary ovarian insufficiency (6,7). 

Women 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 (9,10). 

Sometimes, LH levels can be elevated due to dietary and lifestyle factors and there may be steps you can take to reduce it. Dietary and lifestyle factors that may cause elevated LH levels include: 

  • Smoking (11)
  • Excessive alcohol intake 

What does low LH mean and what causes it? 

Too little LH can lead to problems with ovulation. This includes anovulation, which is not ovulating at all (1). This can also lead to problems with menstruation, such as irregular, missing or complete cessation of periods.  

Eating disorders have been linked to lower LH levels (14,15).  A meningitis infection in the previous 12 months has also been linked to low LH levels (23,24).  Sometimes, LH levels can be decreased due to dietary and lifestyle factors and there may be  steps you can take to increase it. Dietary and lifestyle factors and medications that may cause elevated LH levels include: 

  • A diet rich in soy products or isoflavones (12,13)
  • Excessive exercise (16,17) 
  • Metformin (10,18)
  • Glucocorticoids (19) 
  • Cannabis (20)

What can I do to manage my 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 (23). The use of recreational drugs, including cannabis is not advised if you’re trying to conceive. For advice on how to quit smoking, see the full list of NHS quit smoking services here.

If your LH level is on the lower side, it may be helpful to re-evaluate your diet and exercise regime. Excessive exercise is known to disrupt the release of GnRH from the hypothalamus which has knock-on effects on FSH and LH levels. You can read more about the relationship between exercise and fertility and how much exercise is too much here. If you regularly consume soy or isoflavone products, these may cause excessively high levels of oestrogens, which as mentioned above, suppresses LH release from the pituitary.  However, data on the effects of soy on oestrogen is conflicting and further studies are needed. If you have a vegan diet and regularly use soy-based meat and dairy substitutes, you may want to consider switching to other plant -based protein sources. 

If you have a prescription for glucocorticoid medication, metformin or you have had meningitis in the previous 12 months, these can temporarily decrease your LH levels by disrupting GnRH release from the hypothalamus. 

If you’re concerned about your LH results and would like to speak to someone, we recommend booking a teleconsultation with one of our Hertility experts. 

  1. Luteinizing hormone and its dilemma in ovulation induction
  2. The Normal Menstrual Cycle and the Control of Ovulation 
  3. Physiology, Luteinizing Hormone – StatPearls – NCBI Bookshelf 
  4. Onset of the preovulatory luteinizing hormone surge: diurnal timing and critical follicular prerequisites 
  5. Stimulatory and inhibitory effects of progesterone on FSH secretion by the anterior pituitary 
  6. Primary ovarian insufficiency: an update 
  7. Idiopathic primary ovarian insufficiency: a study of serial hormonal profiles to assess ovarian follicular activity
  8. FSH may be a useful tool to allow early diagnosis of Turner syndrome
  9. Follicle Stimulating Hormone (LH: FSH) Ratio in Polycystic Ovary Syndrome (PCOS) – Obese vs. Non- Obese Women 
  10. Relationship of GnRH‐stimulated LH release to episodic LH secretion and baseline endocrine‐metabolic measures in women with polycystic ovary syndrome 
  11. Ovarian function and cigarette smoking in the BioCycle Study 
  12. Effects of soy foods on ovarian function in premenopausal women 
  13. Effects of soy foods on ovarian function in premenopausal women 
  14. Obstetric and gynecologic problems associated with eating disorders 
  15. Eating disorders from a gynecologic and endocrinologic view: hormonal changes 
  16. 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 
  17. Effect of Exercise on Ovulation: A Systematic Review 
  18. 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 
  19. Glucocorticoids, Stress, and Fertility 
  20. Marihuana Smoking Suppresses Luteinizing Hormone in Women 
  21. Prospective investigation of pituitary functions in patients with acute infectious meningitis 
  22. Hypothalamic pituitary dysfunction in acute nonmycobacterial infections of central nervous system 

Preconception care: caffeine, smoking, alcohol, drugs and other environmental chemical/radiation exposure

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