Luteinizing Hormone (LH)

Sample for Luteinizing Hormone (LH)

1. The serum of the patient is needed.
2. Avoid hemolysis.
3. 24 hours urine sample may be collected. Refrigerate the urine during collection.
4. The serum is stable for 8 days at room temperature.
5. The serum is stable for 14 days at 4 °C.
6. The urine sample should not contain preservatives.

Purpose of the test (Indications)

1. LH, along with FSH, is helpful in determining menopause.
2. LH is helpful in evaluating gonadal failure.
3. LH is helpful for infertility cases to work up.
   1. LH’s essay tells about the occurrence of ovulation.
4.  It tells gonadal failure (insufficiency)  is:
   1. Primary when the problem is in the ovary (or in the testes).
   2. Secondary when the problem is in the pituitary insufficiency.

Precautions for Luteinizing Hormone (LH)

1. Some of the drugs that increase the LH value include Clomiphene, anticonvulsant, and spironolactone.
2. A few drugs decrease the LH estrogen level, Testosterone, Progesterone, oral contraceptives, Digoxin, and Phenothiazine.
3. Patients with HCG-producing tumors and Hypothyroidism may give a false increased level.
4. Avoid lipemic, hemolyzed, or icteric serum.

Pathophysiology of Luteinizing Hormone (LH)

1. LH and FSH are glycoproteins produced in the anterior pituitary gland.
   1. The placenta also produces the LH hormone.
   2. LH has a half-life of one hour.
   3. LH release is stimulated by the gonadotropin-releasing hormone (GTRH).
   1. Because of the feedback mechanism, estrogen and testosterone inhibit the production of LH and FSH.
      1. LH production is suppressed during the luteal phase by negative feedback from the progesterone combined with estradiol, but a low level of LH is necessary for prolonged corpus luteum function.
   2. LH and FSH hormones act on the ovary and testes, called Gonadotropins.

2. GTRH (Gonadotropins releasing hormone) is stimulated when there is a low estrogen level in females and testosterone in males.
   1. The hypothalamus produces GTRH.
3. Both hormones acting on the ovary and testes:
   1. In females, FSH stimulates the development of follicles in the ovary.
   2. LH Stimulate estrogen production from the follicle.
   3. LH stimulates testosterone from the Leydig cells.

4. LH stimulates in the female follicular (ovary) production of:
   1. Estrogen.
   2. Ovulation.
   3. Formation of corpus luteum cyst.
      1. LH in males stimulates Leydig cells to produce testosterone.
      2. LH has a role in the menstrual cycle, giving midcycle surge.
      3. LH stimulates the corpus luteum formation, which supports an embryo in case of fertilization.

Menstrual cycle:

1. Hypothalamus produces GTRH, which acts on the anterior pituitary glands, which produce LH and FSH.
2. There are cyclical hormonal changes in the ovary and the uterus.
3. Changes in the ovary are:
   1. Follicular maturation.
   2. Ovulation.
   3. Formation of corpus luteum.
4. Changes in the uterus are:
   1. Preparation of the endometrium for the implantation of the ovum.
   2. The vagina and cervix are prepared to allow the transfer of sperm.

6. FSH is needed for the maturation of the ovary and testes.
   1. FSH helps in the development of the follicle in the ovary.
   2. FSH stimulates the Sertoli cells in the male.
7. LH and FSH are important for the production of sperm.
   1. LH is necessary for ovulation and corpus luteum formation.
   2. LH is secreted in a variable amount in a day. So one value will not indicate the actual body hormone level.
      1. So several samples are taken, these are pooled, or all the samples are tested for LH.
   3. Raised level of LH and FSH indicates primary gonadal failure like a polycystic ovary or menopause.
      1. In gonadal failure due to the pituitary gland, LH and FSH levels are low.

Spot urine:

1. Spot urine test to detect LH surge is used to evaluate and treat infertility.
   1. This indicates the period when women are most fertile.
   2. LH surge precedes 24 hours of ovulation and can be recognized easily.
   3. A urine 24 hours sample is a better choice to avoid this variable amount of secretion of LH.
   4. LH assay can give a better idea of ovulation. There will be a surge in the LH level.
      1. The best sample is from 11 am to 3 pm.
2. LH surge gives a peak fertility period, which is due to ovulation.
   1. LH surge is between 12 to 16 days of the cycle.
   2. This surge can be found by taking a daily sample near the midcycle.

The normal value of Luteinizing Hormone (LH)

Source 1

Source 2

• Lab values may vary from different labs and different methodologies.

Increased values of Luteinizing Hormone (LH) are seen in the following:

1. A gonadal failure like:
   1. Menopause.
   2. Ovarian dysgenesis. (Turner syndrome).
   3. Testicular dysgenesis (Klinefelter syndrome).
2. Precocious puberty.
3. Pituitary adenoma.
4. Raised level of both  LH and FSH is seen in:
   1. Gonadal failure.
   2. Polycystic ovary.
   3. During menopause.

Decreased values of Luteinizing Hormone (LH) are seen in the following:

1. Pituitary failure. Both LH/ FSH are low.
2. Hypothalamic failure will also lead to low LH and FSH levels.
3. Stress.
4. Anorexia nervosa.
5. Malnutrition.
6. In secondary gonadal failure, the LH and FSH level is low.

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