Luteinizing Hormone (LH)

Luteinizing Hormone (LH)

About the Hormone:
Luteinizing Hormone (LH) is a vital substance secreted in the pituitary gland and contributes to the secretion of estrogen and progesterone in females and testosterone in males. Measurements of this hormone level are essential for diagnosing reproductive system and pituitary gland disorders.

This hormone secretion begins vigorously during the sexual maturation period, and in the female body, it is secreted according to the stages of the menstrual cycle, where its level increases sharply upon the maturation of the egg inside the follicle. This hormone firstly causes ovulation, then the formation of the corpus luteum and the secretion of progesterone. At this time, the level of the vital substance gradually decreases.

In males, luteinizing hormone contributes to the production of testosterone in Leydig cells and ensures a normal process of spermatogenesis.

Synonyms: Luteinizing cell-stimulating hormone, LH, ICSH, Lutropin.

Indications for Testing:
Analysis of luteinizing hormone (LH) level is indicated in the following cases:

  • Infertility in both women and men.
  • Recurrent miscarriage.
  • Early onset or delayed onset of menstruation in girls.
  • Delayed sexual development.
  • Menstrual cycle disorders: scanty menstrual flow, absence of menstruation, bleeding outside the menstrual cycle.
  • Endometritis (inflammation of the uterine lining).
  • Decreased sexual potency.
  • Pathological values ​​in semen analysis. Additionally, blood analysis for LH hormone in women is indicated during preparation for artificial insemination, to determine ovulation time, and during hormone therapy to monitor its effectiveness.

Study Description:
LH analysis is performed using the chemiluminescent immunoassay technique. Blood serum is collected from the vein for this purpose.

Preparation for Analysis:
Blood is drawn for LH analysis on an empty stomach after following a fasting diet for 8-12 hours beforehand. Drinking water is allowed. Several days before the test, stress and physical activity should be avoided. If there are infections in the body during the testing period, it is preferable to postpone the test and perform the diagnosis after recovery.

Blood is drawn for women on days 2-4 of the menstrual cycle, unless otherwise instructed by the doctor. If ovulation is irregular, it is necessary to test values daily between day 8 and day 18 of the menstrual cycle.

The analysis will be unhelpful if steroids or thyroid hormone-containing medications have been taken within 2 days before sample collection, so they should be avoided after consulting the treating physician.

Interpretation of Results:
Measurement Unit: mIU/mL (milli-International Units per milliliter) = mIU/L (milli-International Units per liter).

Reference Values:
Test results vary among individuals of both sexes and different ages. In women, the amount of luteinizing hormone depends on the stage of the menstrual cycle.

AgeLH Level (mIU/mL)Stage
0-12 months<3.29
1-5 years<0.27
5-10 years<0.46
10-14 years<15.26Follicular: 1.68-15, Ovulation: 21.9-56.6, Luteal: 0.61-16.3
14-20 years<15.97Follicular: 1.68-15, Ovulation: 21.9-56.6, Luteal: 0.61-16.3
Over 20 yearsDepends on the stageFollicular: 1.68-15, Ovulation: 21.9-56.6, Luteal: 0.61-16.3
AgeLH Level (mIU/mL)
0-12 months<6.34
1-5 years<0.92
5-10 years<1.03
10-14 years<5.36
14-20 years0.78-4.93
Over 20 years1.14-8.75

These tables provide the reference values for LH levels based on age and stage, aiding in the interpretation of test results.

Please note that intermediate and borderline stages may vary by sex and age, and specific medical guidance.

Possible Results of Increased LH Hormone:

  • Disorders in the function of the reproductive glands, including excessive luteinizing hormone.
  • Postmenopausal in women.
  • Pituitary gland abnormalities associated with increased luteinizing hormone: pituitary tumor.
  • Early onset of menstruation before the age of eight.
  • Polycystic ovary syndrome if luteinizing hormone is reduced or within the normal range.

Decreased hormone levels may result from:

  • Increased prolactin levels in the blood.
  • Overweight.
  • Surgical interventions on the previous day.
  • Absence of menstruation (amenorrhea).
  • Excessive stimulation of the reproductive glands.
  • Dysfunction of the pituitary or hypothalamus, including Sheehan’s syndrome (pituitary dysfunction after childbirth) and weight loss due to the hypothalamus (hypothalamic damage).
  • Genetic diseases (Dien-Morphan disease, dwarfism).
  • Disorders in the maturation stage in women.

When there is a deviation from normal values, further tests are recommended. A single test result cannot be the sole basis for diagnosing the disease, so multiple tests are recommended under the supervision of a specialist physician.

Consultation with a gynecologist, andrologist, endocrinologist, and pediatrician (if the patient is under 18 years old) is recommended if the disease involves children. X-rays and additional blood tests are essential for determining the diagnosis. These tests typically include: