Fertility depends on a number of factors, with the functioning of the pituitary gland being the most essential of them. The pituitary gland produces hormones that influence fertility: luteinising hormone (luteus is Latin for yellow, LH) and follicle-stimulating hormone (FSH). The production of LH is regulated by hormones secreted by the ovaries, testicles, and hypothalamus.
The primary purpose of LH is to regulate the production of sex hormones and gametes in the ovaries in women and in the testicles in men.
In women, a rapid surge of LH triggers ovulation, or the release of an egg, once the follicle has developed. After ovulation, LH supports the function of the corpus luteum developing in place of the follicle and the secretion of progesterone. Progesterone prepares the lining of the uterus for pregnancy.
In men, luteinising hormone controls the Leydig cells that secrete testosterone.
When should LH be measured?
Measuring LH levels can help in investigating infertility, irregular menstrual periods, and pituitary gland disorders. In children, FSH and LH levels are examined for diagnosing delayed or early puberty and examining growth problems.
FSH and LH levels can also be measured to find out whether problems are caused by ovarian insufficiency or a disorder of the pituitary gland.
LH should be measured when the following symptoms are present:
- Disturbance of the menstrual cycle
- Night sweats
- Sleep disorders
- Mental disorder
- Loss of libido
- Vaginal dryness
- Determining the time of ovulation
- Testosterone deficiency in men (hypogonadism, a condition caused by diminished production of sex hormones)
What does the test measure?
The test indicates the level of LH in the blood. The test is often taken when examining the cause of infertility or examining the functioning of the pituitary gland.
How to interpret the LH test result?
Normally, the result is:
- Women, follicular phase: 3.0–12 IU/l
- Women, ovulation surge: 15.0–80 IU/l
- Women, luteal phase: 2.5–10 IU/l
- Women, postmenopause: 20.0–80 IU/l
- Men under 50 years: 2.5–7 IU/l
- Men over 50 years: 2,5–12 IU/l
The reference values of this examination have changed 11.10.2021. You will find your own result's reference values from My LOUNA in touch with the graph. Read more about defining reference values.
Please contact your physician or other healthcare professional if you suspect an illness or need help interpreting the results.
What can cause elevated levels in the LH?
Elevated values can be caused by:
- Ovarian insufficiency
- Premature puberty in young children
- Premature menopause due to ovary removal surgery or ovarian damage as a consequence of radiotherapy
- Hypothyroidism (underactive thyroid)
- Polycystic ovary syndrome (PCOS)
- In men, reduced functioning of the testicles (Klinefelter syndrome)
- Disease of the adrenal gland
- Ovarian cancer
What can cause decreased levels in the LH?
- The body can secrete low LH and FSH levels, causing ovarian insufficiency because of the functioning of the pituitary gland or hypothalamus.
- Contraceptive pills and hormone treatments also cause low LH levels.
- Low LH values are seen in connection with eating disorders (anorexia nervosa).
The most typical additional LH tests:
- Oestradiol affects the brain, bones, organs, and reproduction (1366 S-E2)
- Testosterone has physical effects on social and sexual behaviour (2735 S-Testo, 2737 S-SHBG)
- Follicle stimulating hormone affects the growth and maturation of eggs (1422 S-FSH)
- Progesterone prepares the lining of the uterus for pregnancy (2502 S-Prog)
SYNLAB test list: FSH https://www.yml.fi/tuotekuvaus_show.php?tuotenro=257
Terveyskirjasto health library: Aivolisäkkeen vajaatoiminta (hypopituitarismi) https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=dlk00996&p_hakusana=luteinisoiva%20hormoni
Terveyskirjasto health library: Normaali kuukautiskierto https://www.terveyskirjasto.fi/terveyskirjasto/tk.koti?p_artikkeli=dlk00158&p_hakusana=luteinisoiva%20hormoni
Suomen endokrinologiyhdistys: Miehen hypogonadismi eli mieshormonin puutostila https://www.endo.fi/tietoa-endokrinologisista-sairau/potilasohjeet/miehen-hypogonadismi-eli-mieshor/
LabTest online: LH test https://labtestsonline.org.uk/tests/lh-test
Fasting is not required
This examination does not require fasting