LH, Luteinizing Hormone

This is a test used to check your pituitary function. It is often used to investigate infertility issues. This test may be done if you are having difficulty getting pregnant or are having irregular menstrual periods or if your doctor thinks that you have symptoms of a pituitary or hypothalamic disorder.

Luteinizing hormone (LH) is produced by the pituitary gland in the brain. Control of LH production is a complex system involving hormones produced by the gonads (ovaries or testes), the pituitary, and the hypothalamus, such as gonadotrophin-releasing hormone.

Women's menstrual cycles are divided into 2 phases, the follicular and luteal, by a mid-cycle surge of follicle-stimulating hormone (FSH) and LH. The high level of LH (and FSH) at mid-cycle triggers ovulation. LH also stimulates the ovaries to produce steroids, primarily estradiol. Estradiol and other steroids help the pituitary to regulate the production of LH. At the time of menopause, the ovaries stop functioning and LH levels rise.

In men, LH stimulates the Leydig cells in the testes to produce testosterone. LH levels are relatively constant in men after puberty. Testosterone provides negative feedback to the pituitary and the hypothalamus, helping to regulate the amount of LH secreted.

In infants and children, LH levels rise shortly after birth and then fall to very low levels (by 6 months in boys and 1-2 years in girls). At about 6-8 years, levels again rise with the beginning of puberty and the development of secondary sexual characteristics.

PREPARATION FOR TEST

A blood sample is obtained by inserting a needle into a vein in the arm.

NORMAL FINDINGS

Values may vary depending on assay method.

Age / Luteinizing Hormone (international units/L) / Follicle-Stimulating Hormone (international units/L)

  • Adult, Male / 1.24-7.8 / 1.42-15.4

  • Adult, Female, Follicular phase / 1.68-15 / 1.37-9.9

  • Adult, Female, Ovulatory peak / 21.9-56.6 / 6.17-17.2

  • Adult, Female, Luteal phase / 0.61-16.3 / 1.09-9.2

  • Adult, Female, Postmenopause / 14.2-52.3 / 19.3-100.6

  • Child (age 1-10 years), Male / 0.04-3.6 / 0.3-4.6

  • Child (age 1-10 years), Female / 0.03-3.9 / 0.68-6.7

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

MEANING OF TEST

Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.

OBTAINING THE TEST RESULTS

It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.