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FSH and LH Test

What is FSH and LH?

Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH) are made by your pituitary gland, a small gland located underneath the brain. FSH and LH play an important role in sexual development and functioning.

FSH helps control the menstrual cycle and stimulates the growth of eggs in the ovaries. FSH levels in women change throughout the menstrual cycle, with the highest levels happening just before an egg is released by the ovary. This is known as ovulation.

LH helps control the menstrual cycle. It also triggers the release of an egg from the ovary. This is known as ovulation. LH levels quickly rise just before ovulation.

In children, FSH and LH levels are usually low until puberty, when levels begin to rise. FSH and LH helps signal the ovaries to make estrogen.

Too much or too little FSH and LH can cause a variety of problems, including infertility (the inability to get pregnant), menstrual difficulties or delayed puberty in children.

What is the FSH and LH test used for?

FSH and LH test work closely together and are usually done together. These tests are used in different ways, depending on whether you are a woman or a child.

In women, these tests are most often used to:

  • Help find the cause of infertility

  • Find out when ovulation occurs, this is the time when you are most likely to get pregnant.

  • Find the reason for irregular or stopped menstrual periods.

  • Confirm the start of menopause, or perimenopause. Menopause is the time in a woman's life when her menstrual periods have stopped, and she can't become pregnant anymore. It usually starts when a woman is around 50 years old. Perimenopause is the transition period before menopause. It can last for several years. LH testing may be done towards the end of this transition.

In children, these tests are most often used to help diagnose early or delayed puberty.

  • Puberty is considered early if it starts before age 9 in girls.

  • Puberty is considered delayed if hasn't started by age 13 in girls.

Why do I need the FSH and LH test?

If you are a woman, you may need this test if:

  • You've been unable to get pregnant.

  • Your menstrual cycle is irregular.

  • Your periods have stopped. The test may be used to find out if you have gone through menopause or are in perimenopause.

You may need testing if they have symptoms of a pituitary disorder. These include some of the symptoms listed above, as well as:

  • Fatigue

  • Weakness

  • Weight loss

  • Decreased appetite

Your daughter may need the FSH and LH test if she is does not seem to be starting puberty at the right age (either too early or too late).

What do the results mean?

In a woman, high FSH and LH levels may mean you have:

  • Primary ovarian insufficiency (POI), also known as premature ovarian failure. POI is the loss of ovarian function before the age of 40.

  • Started menopause or are in perimenopause

  • A pituitary tumor

  • Turner syndrome, a genetic disorder that affects sexual development in females. It often causes infertility.

If your LH is considerably higher than your FSH it can also mean that you have polycystic ovary syndrome (PCOS). PCOS is a common hormone disorder affecting childbearing women. It is one of the leading causes of female infertility due to absence of or dysfunctional ovulation.

In a woman, low FSH and LH levels may mean:

  • Your ovaries are not making enough eggs.

  • Your pituitary gland is not working correctly.

  • You have a problem with your hypothalamus, a part of the brain that controls the pituitary gland and other important body functions.

  • You are very underweight or malnourished

  • You have functional hypothalamic amenorrhea

In children, high FSH and LH levels, may mean puberty is about to start or has already started. If this is happening before age 9 in a girl (precocious puberty), it may be a sign of:

  • A disorder of the central nervous system

  • A brain injury

Low FSH and LH in girls may be a sign of delayed puberty. Delayed puberty may be caused by:

  • A disorder of the ovaries

  • Turner syndrome

  • An infection

  • A hormone deficiency

  • An eating disorder


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