Luteinizing Hormone
Luteinizing hormone (LH) is a chemical in your body that triggers important processes in your reproductive system. LH spurs ovulation and helps with the hormone production needed to support pregnancy.
What is Luteinizing hormone?
Luteinizing hormone (LH) stimulates processes in your body that are important for sexual health, development and reproduction.
A tiny structure in your brain called the pituitary gland secretes LH.
In turn, LH causes changes in your sex organs your ovaries or testes that allow your reproductive system to function correctly.
What does Luteinizing hormone do?
Your pituitary gland secretes two important hormones that work together to regulate processes in your reproductive system: follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
These hormones are chemical messengers that signal your sex organs (ovaries or testes) to start processes needed to support your reproductive health.
Think of LH as a chemical agitator that spurs your reproductive system to action.
Your sex organs produce either steroids or hormones (progesterone, testosterone) in response to LH.
In the pituitary of people designated female at birth (DFAB), LH is released only in the second part of the menstrual cycle.
That is, after an initial surge causes the release of an egg (ovulation), LH is released at a constant pace for two weeks.
This stimulates ovarian progesterone production.
In the pituitary of people designated male at birth (DMAB), LH is released at a constant pace over time and testosterone is produced at a constant level, as well.
Luteinizing hormone in women or DFAB
LH stimulates changes in your ovaries that maintain your menstrual cycle and support pregnancy
LH causes these changes in people designated female at birth (DFAB), including cisgender women and some transgender men and nonbinary people with vaginas.
Ovulation: A surge in LH causes your ovary to release a mature egg around the second week of each menstrual cycle. A high LH level around this time means that you’re at that moment in your cycle when you’re most likely to get pregnant.
Progesterone production: LH causes a structure in your ovary called the corpus luteum to produce more progesterone during the third and fourth week of your menstrual cycle. Progesterone is a hormone that’s needed to support the early stages of pregnancy.
Luteinizing hormone in men or DMAB
LH stimulates your testes to make testosterone, a hormone your body needs to produce sperm.
Testosterone is also responsible for secondary sex characteristics, like a deeper voice and more body hair and muscle mass.
LH causes testosterone release in people designated male at birth (DMAB), including cisgender men and some transgender women and nonbinary people with penises.
What happens when Luteinizing hormone levels are high?
High LH levels can signify that your sex organs aren’t producing enough steroid hormones needed for a reproductive process to take place.
This is typical of when the ovaries and testes have exhausted their ability to produce estrogen and testosterone, from genetic, autoimmune, surgical, or physiologic causes.
Turner syndrome or Fragile X in DFAB people and Klinefelter syndrome in DMAB people are examples of genetic conditions associated with high LH levels.
Polycystic ovary syndrome (PCOS) is a condition that affects DFAB people that can cause mildly elevated LH levels.
These are associated with irregular periods and infertility.
What happens when Luteinizing hormone levels are low?
Low LH levels can signify that your pituitary gland isn’t making the LH needed to spur changes in your body that support sexual development or reproduction.
Low LH levels can be a sign of:
Kallmann syndrome: A rare condition that leads to insufficient testosterone and estrogen production.
Functional Hypothalamic Amenorrhea: When irregular or missed periods are related to excessive exercise habits.
What is a normal Luteinizing hormone level?
When you get your test results, remember that what’s considered normal depends on various factors, including your age, gender and medical history.
For DFAB people, the timing of your menstrual cycle or whether you’ve gone through menopause will affect your LH levels.
The numbers below provide a general snapshot of normal LH levels for cisgender men and women. Ask your healthcare provider what your test results mean for you.
Women, weeks one and two of the menstrual cycle: 1.37 to 9 IU/L (international units per liter).
Women, week two, before ovulation: 6.17 to 17.2 IU/L.
Women, weeks three and four of the menstrual cycle: 1.09 to 9.2 IU/L.
Women, postmenopausal: 19.3 to 100.6IU/L.
Men: 1.42 to 15.4 IU/L.