Luteinizing hormone: the norm in women and men
The content of the article:
- LH blood test
- LH norms
- Conditions in which LH is elevated
- Conditions in which LH levels are low
Luteinizing hormone (LH) is a peptide hormone that is produced by the gonadotropic cells of the anterior pituitary gland. Together with the follicle stimulating agent, it ensures the normal functioning of the reproductive system.
Synonyms: luteotropin, lutropin.
The hormone is synthesized in the brain, in the anterior pituitary gland
LH is essential for reproductive function in both women and men. In a woman's body, it stimulates the production of estrogen by the ovaries, a peak increase in its concentration causes ovulation. When the egg is released, the residual follicle turns into a corpus luteum, which begins to produce progesterone in order to prepare the endometrium for the possible implantation of a fertilized egg into the uterus. LH maintains the corpus luteum for about two weeks. In men, luteinizing hormone stimulates the Leydig cells of the testes, which produce testosterone, which is involved in spermatogenesis.
The structure of LH is similar to other glycoproteins (follicle-stimulating hormone, thyroid-stimulating hormone, human chorionic gonadotropin, etc.). The hormone has a dimeric structure, consists of α and β subunits, which are interconnected by disulfide bridges. For all these glycoproteins, the α-subunits are identical, but the β-subunits are different. The beta subunit of LH has 121 amino acids, which determines its biological effect.
The release of LH is controlled by the rhythmic release of gonadotropin-releasing hormone by the hypothalamus, while the frequency of release depends on the release of estrogen by the gonads (according to the principle of feedback).
The method for determining the onset of ovulation is based on the detection of a surge in LH. For several days before the expected ovulation, the level of the hormone in the urine is measured daily. This test is used by couples planning a pregnancy to determine the most appropriate time for conception, but it is not recommended for use for contraception, as sperm, once in the female genital tract, remain viable for several days.
Luteinizing hormone is a marker of age-related changes and dysfunctions of the hypothalamic-pituitary-ovarian system.
LH blood test
The clinical significance of determining the concentration of luteinizing hormone in women is in the diagnosis of ovulatory dysfunction (as one of the causes of infertility), menstrual irregularities, and recurrent miscarriage. The analysis is used for the differential diagnosis of hyperandrogenic conditions (hormone-producing ovarian neoplasms, polycystic ovary syndrome).
In men, determining the level of LH is one of the studies to determine the cause of gonadal dysfunction. In children, the analysis is an integral part of the diagnosis of delayed puberty and early puberty.
An analysis for luteinizing hormone is prescribed for the following indications:
- lack of menstruation;
- intermenstrual bleeding;
- scanty and / or short (less than 3 days) menstruation;
- infertility;
- a history of miscarriages;
- polycystic ovary syndrome;
- decreased libido;
- growth retardation;
- hirsutism;
- delayed or premature sexual development;
- determination of ovulation;
- in vitro fertilization (IVF).
In addition, the study of the concentration of LH in the blood is carried out in order to monitor the effectiveness of the hormone therapy.
Depending on the purpose of the LH test, blood should be donated to females on certain days of the cycle.
Two days before the study, it is necessary to stop taking steroid and thyroid hormones, give up excessive physical and mental stress in a day, and exclude smoking for three hours.
Blood sampling for analysis should be done on an empty stomach, in the morning. Venous blood is drawn into an empty tube or into a tube (vacutainer) with a separating gel. During blood sampling, the patient is in a sitting or lying position.
LH norms
The rate of luteinizing hormone in women of reproductive age varies depending on the phase of the menstrual cycle:
- follicular phase - 1.9-12.5 U / l;
- ovulation - 8.7–76.3 U / l;
- luteal phase - 0.5-16.9 U / l;
- postmenopause - 15.9-54.0 U / l.
In patients taking oral contraceptives, the normal LH content is 0.7-5.6 U / L. Norms may differ depending on the test method in different laboratories.
In patients of reproductive age with polycystic ovary syndrome, the normal ratio of luteinizing and follicle-stimulating hormones is disturbed, but in such cases, the level of LH usually does not go beyond the normal range.
In women, the content of the hormone in the blood depends on the phase of the menstrual cycle.
The norm of the content of luteinizing hormone for girls:
- up to 18 months - no more than 2.3 U / l;
- from 18 months to 9 years - up to 1.3 U / l;
- from 9 to 18 years old - 0.4–19.0 U / L (varies depending on Tanner's stage), with a steady menstrual cycle, it depends on the phase of the cycle.
For boys:
- from 1 month to 3 years - no more than 4.1 U / l;
- from 3 to 9 years old - up to 3.8 U / l;
- from 9 years and older - 1.5-9.3 U / L (varies depending on the Tanner stage).
In children with precocious puberty, LH is usually in the normal range for reproductive age, exceeding the limits for the biological age of the child.
Conditions in which LH is elevated
A persistently elevated concentration of LH indicates a disturbance in the normal feedback between the gonads and the hypothalamus. In persons of reproductive age, a high level of the hormone in the blood is observed with the following pathologies:
- ovarian hypofunction;
- polycystic ovary syndrome;
- premature menopause;
- endometriosis;
- some forms of congenital adrenal hyperplasia;
- gonadal dysgenesis (Swier's syndrome);
- Shereshevsky-Turner syndrome;
- pituitary neoplasms;
- renal failure;
- anorchism (congenital absence of the testicle);
- cryptorchidism (undescended testicle into the scrotum);
- atrophy of the gonads in men due to inflammation of the testicles (after suffering from mumps, gonorrhea, brucellosis);
- damage to testicular tissue against the background of alcoholism, exposure to the body of ionizing radiation, toxic substances, etc.;
- taking a number of medicines;
- stressful situations;
- fasting, a sharp and significant decrease in body weight.
Luteinizing hormone is elevated in women during menopause. Excessive physical activity, including intense sports, can increase its concentration in the blood in persons of reproductive age.
Conditions in which LH levels are low
Low LH concentration is typical for the following pathologies:
- neoplasms of the hypothalamus;
- traumatic brain injury with damage to the hypothalamus;
- Kallman syndrome (combination of hypogonadism with impaired sense of smell);
- hypopituitarism (complete or partial cessation of the production of hormones by the anterior pituitary gland);
- insufficiency of the luteal phase;
- amenorrhea of athletes;
- increased concentration of prolactin in the blood;
- surgical interventions;
- unbalanced diet;
- obesity;
- bad habits;
- taking certain medications (primarily gonadoliberin agonists or antagonists).
Low LH levels are common in women during pregnancy.
Measurement of the level of LH in the blood is carried out during the diagnosis of infertility and recurrent miscarriage
Decreased production of the hormone can lead to the development of hypogonadism, which in men is manifested by a decrease in sperm count, which causes infertility. In women, this condition causes the development of amenorrhea.
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Anna Aksenova Medical journalist About the author
Education: 2004-2007 "First Kiev Medical College" specialty "Laboratory Diagnostics".
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