The luteinizing hormone, also called LH, is a hormone produced by the pituitary gland and which, in women, is responsible for follicle maturation, ovulation and progesterone production, having a fundamental role in the woman's reproductive capacity. In men, LH is also directly related to fertility, acting directly on the testicles and influencing sperm production.
In the menstrual cycle, LH is found in higher concentrations during the ovulatory phase, however it is present throughout the woman's life, having different concentrations according to the phase of the menstrual cycle.
In addition to playing an important role in verifying the reproductive capacity of men and women, the concentration of LH in the blood helps in the diagnosis of tumors in the pituitary gland and changes in the ovaries, such as the presence of cysts, for example. This test is more requested by the gynecologist to check the woman's health, and is usually requested together with the measurement of FSH and Gonadotropin Releasing Hormone, GnRH.
What is it for
The measurement of luteinizing hormone in the blood is usually required to check the person's reproductive capacity and assist in the diagnosis of some changes related to the pituitary, hypothalamus or gonads. Thus, according to the amount of LH in the blood, it is possible to:
- Diagnose infertility; Evaluate the sperm production capacity by men; Check if the woman has entered menopause; Assess the causes of the absence of menstruation; Check if there is adequate egg production in the case of women; Assist in the diagnosis of tumor in the pituitary, for example.
In men, the production of LH is regulated by the pituitary gland and acts directly on the testicles, regulating the production of sperm and the production of hormones, especially testosterone. In women, the production of LH by the pituitary gland stimulates the production of progesterone, mainly, and estrogen, being essential for pregnancy.
In order to assess the reproductive capacity of both men and women, the doctor may also request the measurement of FSH, which is a hormone that is also present in the woman's menstrual cycle and influences the production of sperm. Understand what it is for and how to understand the FSH result.
LH reference values
The reference values of luteinizing hormone vary according to age, gender and phase of the menstrual cycle, in the case of women, the values being:
Children: less than 0.15 U / L;
Men: between 0.6 - 12.1 U / L;
Women:
- Follicular phase: between 1.8 and 11.8 U / L; Ovulatory peak: between 7.6 and 89.1 U / L; Luteal phase: between 0.6 and 14.0 U / L; Menopause: between 5.2 and 62.9 U / L.
The analysis of the results of the exams must be done by the doctor, as it is necessary to analyze all the exams together, as well as the comparison with the previous exams.
Low luteinizing hormone
When the LH values are below the reference value, it can be indicative of:
- Alteration in the pituitary gland, resulting in a decrease in the production of FSH and LH; Deficiency in the production of gonadotropin (GnRH), which is a hormone produced and released by the hypothalamus and whose function is to stimulate the pituitary gland to produce LH and FSH; Kallmann, which is a genetic and hereditary disease characterized by the absence of GnRH production, which leads to hypogonadotrophic hypogonadism; Hyperprolactinemia, which is the increase in the production of the hormone prolactin.
The decrease in LH can lead to a decrease in the production of sperm by men and in the absence of menstruation in women, a situation known as amenorrhea, and it is important to consult the doctor so that the best treatment is indicated, which is usually done with the use of hormonal supplementation..
High luteinizing hormone
The increase in LH concentration may be indicative of:
- Pituitary tumor, with an increase in GnRH and, consequently, LH secretion; Early puberty; Testicular failure; Early menopause; Polycystic Ovary Syndrome.
In addition, the LH hormone may be increased in pregnancy, because the hCG hormone can mimic LH, and may appear elevated on exams.
