Luteinizing hormone, LH

What is LH?

Luteinizing hormone (LH) is primarily a fertility hormone present in both men and women. In women, LH affects the ovaries, stimulating ovulation and the synthesis of progesterone.  In males, it affects the testes.  LH has a role in puberty, menstruation, and fertility.

Why test LH?

Unless this is ordered as a retest or for a specific reason, we recommend ordering this as part of a health test.

LH is used as included in a panel of tests to evaluate a woman’s reproductive function and menstrual problems.  Determining your blood LH levels can indicate underlying problems associated with a variety of reproductive health issues.

Reasons to test your LH include:


  • You are struggling to get pregnant or have suffered infertility or miscarriage
  • You want to evaluate your fertility health
  • You suspect that you have entered perimenopause or menopause
  • You have irregular or absent menstrual periods or other suspected problems, e.g., Polycystic Ovarian Syndrome (PCOS)

Men :

  • You have signs of low testosterone levels, such as low muscle mass or a decreased sex drive

Experts disagree about the extent to which men should test their hormones as part of a fertility assessment. It is thought that, in the majority of cases, male hormones are not the cause of male infertility.

Other factors that contribute to male infertility include, inflammation of the veins that drain the testicles, infection, antibodies attacking the sperm, thyroid-/ adrenal-/ pituitary- imbalances, nutrient deficiencies, Celiac disease, and medications. (Mayo Clinic).

LH is also tested to investigate pituitary tumours but this is out of Nordic Wellth’s scope of practice.

What causes low LH?

Low or high levels do not necessarily indicate a problem if there are no symptoms. If you are woman low LH levels may mean:

Your pituitary gland is not working correctly

If you are a man, low LH levels may mean you have a disorder of the pituitary gland or the hypothalamus. Low LH and FSH levels in children may be a sign of delayed puberty, that could be caused by:

  • Ovarian or testicle disorder
  • Turner Syndrome (girls)
  • Klinefelter's syndrome (boys)
  • Infection
  • Hormone deficiency
  • Eating disorder (s)

What causes high LH?

The results of this test are complex and need to be looked at by your doctor considering other test results. LH is used alongside other tests. LH and FSH levels can help to distinguish between primary ovarian failure (direct ovarian failure or lack of ovarian development) and secondary ovarian failure (ovarian failure due to disorders of either the pituitary or the hypothalamus).

Secondary ovarian failure causes low levels of LH and FSH and indicate a problem with the pituitary or hypothalamus.  In women who are trying to get pregnant, several LH tests can help identify the surge prior to ovulation An LH surge indicates that ovulation has occurred.

You have more circulating LH than expected. High levels do not necessarily indicate a problem if there are no symptoms.  The significance of LH results depends on a few factors, such as your gender, and your age.  If you are woman high LH levels may mean you:

  • Are not ovulating. If you are of childbearing age, this may mean you have a problem in your ovaries. If you are older, it may mean you have started menopause or are in perimenopause.
  • Have polycystic ovary syndrome (PCOS). PCOS is a common hormone disorder affecting childbearing women. It is one of the leading causes of female infertility.
  • Have Turner syndrome, a genetic disorder affects sexual development in females. It often causes infertility.


In postmenopausal women, an increase in LH levels may play a role in the development of Alzheimer’s Disease. LH promotes the deposition of amyloid β plaques in the hippocampus, as seen in Alzheimer’s Disease.

If you are a man, high LH levels may mean:

  • Your testicles were damaged by chemotherapy, radiation, infection, or alcohol abuse.
  • You have Klinefelter's syndrome, a genetic disorder that affects sexual development in males. It often causes infertility.

In children, high LH levels, along with high levels of follicle-stimulating hormone, may mean puberty is about to start or has already started. If this is happening before age 9 in a girl or before age 10 in a boy (precocious puberty), it may be a sign of:

  • A disorder of the central nervous systems
  • A brain injury

More information

LH levels should rise at mid-cycle, about 24 to 36 hours before ovulation occurs. High levels of LH on day 3 may indicate disorders such as polycystic ovary disease or ovarian failure.  If you take hormonal contraceptives, the results of this test may not be accurate.

This test should not be performed during ongoing or after recently completed antibiotic treatment.  If the purpose is to evaluate your fertility, this test should be taken on day 3 (or at least between days 2-5). A woman’s menstrual cycle is measured from the first day of her period (blood flow, not spotting), so Cycle Day 3 is the third day of her period.

On the day of the test
Remember to take I.D. with you when going to take a test.


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