LH

What is being tested?
Luteinising 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 and testicles), the pituitary gland and the hypothalamus.
A woman’s menstrual cycle is divided into the follicular and luteal phases, with a mid-cycle surge in follicle-stimulating hormone (FSH) and LH. The high mid-cycle level of LH (and FSH) triggers ovulation. LH stimulates the ovaries to produce steroids, mainly oestradiol. Oestradiol and other steroids help the pituitary gland regulate LH production. At the menopause the ovaries stop working and LH levels rise.
In men, LH stimulates a particular type of cell in the testicles (Leydig cells) to produce testosterone. LH levels (in males sometimes called interstitial cell-stimulating hormone, or ICSH) are relatively constant in men after puberty. A rising testosterone level has an inhibitory effect (negative feedback) on the pituitary gland and hypothalamus, reducing the amount of LH released.
In newborn babies and children, LH levels rise quickly after birth and then fall to very low levels (from 6 months in boys and from 1-2 years in girls). At about 6-8 years, hormone levels begin to rise again before the onset of puberty and the development of secondary sexual characteristics.

How is the sample collected for testing?
A blood sample is taken with a needle from a vein in the arm, or a random urine sample is used. If the doctor wants to measure the amount of LH produced over the day, a 24-hour urine collection may be requested. LH is released intermittently throughout the day, so a random sample may not give a true reading. A 24-hour urine collection can eliminate this variation.

Is any preparation needed to ensure the quality of the sample?
No preparation is needed, but in women, for example, samples must be collected at specific times in the menstrual cycle

1. How is it used?
2. When is it requested?
3. What does the test result mean?
4. Is there anything else I should know?

1. How is it used?
LH is often used together with other tests (FSH, testosterone, oestradiol and progesterone) to investigate infertility in men and women. LH levels are also useful in investigating menstrual irregularities and in helping to diagnose pituitary disorders or diseases affecting the ovaries or testicles.
Once a baseline urine test has been done, further urine tests can be used to detect the LH surge, which indicates that ovulation will occur in the next 1-2 days.
In children, FSH and LH are used to diagnose early or delayed puberty.
LH is sometimes measured in response to gonadotrophin-releasing hormone (GnRH) to distinguish between primary and secondary disorders involving the hypothalamus, pituitary gland or gonads. GnRH is the hormone produced by the hypothalamus that stimulates the pituitary gland to release LH and FSH. For this test, after a baseline blood sample has been taken, the patient is given GnRH intravenously. Further blood samples are then taken in sequence and LH is measured. This test can help distinguish between disease of the ovaries or testicles (primary) and a disorder of the pituitary gland or hypothalamus (secondary). It is also often useful in assessing early or delayed puberty.

2. When is it requested?
In women and men, LH (and FSH) tests are requested as part of the investigation of infertility, when pituitary or gonadal disorders are suspected, when a woman has difficulty getting pregnant, or when pituitary, ovarian or gonadal disorders are suspected.
The test may be requested together with FSH when a woman has irregular periods, especially at the start of the menopause.
LH and FSH may be requested when a boy or girl does not seem to have entered puberty at the appropriate age (either too late or too early). Signs of early puberty can include:

• Breast enlargement in girls
• Growth of pubic hair
• Growth of the genitals in boys
• Start of periods in girls
• Start of periods in girls

Irregular onset of puberty can indicate a more serious problem involving the hypothalamus, pituitary gland, gonads (ovaries and testicles) or other systems. Measuring LH and FSH can help distinguish between symptoms of benign and serious disease. Once it has been established that the symptoms are the result of real disease, further tests can be done to find the underlying cause.

3. What does the test result mean?
In women, LH and FSH levels can help distinguish between primary ovarian failure (failure of the ovaries themselves or failure of the ovaries to develop) and secondary ovarian failure (ovarian problems due to disorders of the pituitary gland or hypothalamus). Raised LH and FSH levels are seen in primary ovarian failure. Some causes of primary ovarian failure are listed below.
Developmental defects:

• Failure of the ovaries to develop (ovarian agenesis)
• Chromosomal abnormalities, such as Turner syndrome and Kallmann syndrome
• Defects in steroid production by the ovaries, such as 17-alpha-hydroxylase deficiency

Premature ovarian failure due to:

• Radiation
• Chemotherapy
• Autoimmune diseases

Chronic failure to ovulate (anovulation) due to:

• Polycystic ovary syndrome (PCOS)
• Adrenal diseases
• Thyroid diseases
• Ovarian tumour

During the menopause a woman’s ovaries stop working, so LH levels rise.
Low LH and FSH levels are seen in secondary ovarian failure and indicate a problem with the pituitary gland or hypothalamus.
In men, high LH levels may indicate primary testicular failure. This may be due to developmental defects in the growth of the testicles or to damage to the testicles, as described below.

Developmental defects:

• Failure of the gonads to develop (gonadal agenesis)
• Chromosomal abnormality, for example Klinefelter syndrome

Testicular failure:

• Viral infection (mumps)
• Injury
• Chemotherapy
• Autoimmune diseases
• Germ cell tumours

The LH response to GnRH stimulation can help distinguish between primary dysfunction (problems with the ovaries or testicles) and a secondary disorder (a problem involving the hypothalamus or pituitary gland). Once the baseline LH level has been measured, a dose of GnRH is given by injection. A subsequent rise in LH indicates that the pituitary gland has responded to GnRH and suggests a disorder involving the ovaries or testicles. A lack of rise in LH shows that the pituitary gland has not responded to GnRH and indicates a disease involving the pituitary gland or hypothalamus.
In young children, high LH and FSH levels together with the development of secondary sexual characteristics at an unusually young age indicate precocious puberty. This is much more common in girls than in boys. This early development can have several underlying causes that must be diagnosed and treated. Some of the causes are:

• Central nervous system lesions
• Hormone-secreting tumours
• Ovarian tumours or cysts
• Testicular tumours

Normal prepubertal levels of LH and FSH in children who show some signs of pubertal change may indicate a benign form of early puberty with no underlying or identifiable cause, or it may simply be a normal variant of puberty.
In delayed puberty, LH and FSH may be normal or lower than expected for a young person of that age. The test of the LH response to GnRH, together with other tests, can help diagnose the cause of delayed puberty. Some of the causes of delayed puberty can include:

• Gonadal failure (ovaries or testicles)
• Hormone deficiency
• Turner syndrome (chromosomal abnormality in females)
• Klinefelter syndrome (chromosomal abnormality in males)
• Chronic infections
• Cancer
• Eating disorders (anorexia nervosa)

4. Is there anything else I should know?
Some medicines can raise LH, such as anticonvulsants, clomifene and naloxone, while others lower LH, such as digoxin, oral contraceptives and hormone treatments.
A recent nuclear medicine scan can interfere with LH test results if the method used to measure it uses radioisotopes

1. I can’t get pregnant. What tests do I need?
2. Can the LH test be used to find out whether I have ovulated?
3. I’m a young woman, but I’m now growing facial hair and I still don’t have regular periods. What’s wrong with me?
4. Why would a man need a test for female hormones?
5. Is there a home test for LH?

1. I can’t get pregnant. What tests do I need?
Basic fertility tests often include measuring LH and FSH. The doctor may also ask you to record your body temperature, which rises slightly during ovulation. Other hormone tests may be carried out, as may a post-coital test (after sexual intercourse). A hysterosalpingogram (an image of the fallopian tubes) may be indicated to see whether the fallopian tubes are blocked. Your partner may be asked to provide a semen sample for analysis.

2. Can the LH test be used to find out whether I have ovulated?
The LH test is often used to predict ovulation by detecting the sharp rise in LH that precedes a woman’s monthly ovulation. However, it cannot be used to confirm that ovulation has taken place.

3. I’m a young woman, but I’m now growing facial hair and I still don’t have regular periods. What’s wrong with me?
You may have polycystic ovary syndrome (PCOS), a hormonal problem seen in 7-10% of women and one of the main causes of infertility. In this condition the ovaries may become larger because of cysts that form inside them. Women with PCOS may also have high androgen levels and not ovulate normally. You may need laboratory tests, including LH, FSH and androgens, to make sure that PCOS is the condition causing your symptoms. A combination of medicines and hormone treatment can help relieve the symptoms.

4. Why would a man need a test for female hormones?
Men also produce FSH and LH. These hormone levels are important for male fertility. In men, FSH stimulates the testicles to produce sperm, just as in women FSH stimulates the ovaries to produce eggs. In men, LH may be measured if testosterone levels are low.

5. Is there a home test for LH?
Yes, there is a home test that uses a urine sample and helps predict ovulation. For more information, see the article on home testing and the FDA website