Luteinizing Hormone (LH), Lutropin

Sample

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 to determine menopause.
2. LH is helpful in evaluating the gonadal failure.
3. LH is helpful for infertility cases to work up.
   1. LH 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

1. Some of the drugs given to increase the LH value like Clomiphene, anticonvulsant, and spironolactone.
2. There are a few drugs that decrease the level of LH are estrogen, 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

1. LH and FSH are glycoproteins produced in the anterior pituitary gland.
   1. LH hormone is also produced by the placenta.
   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 the prolonged corpus luteum function.
   2. Both hormones, LH and FSH act on the ovary and testes, these are called as Gonadotropins.

2. GTRH (Gonadotropins releasing hormone) is stimulated when there is a low level of estrogen in females and testosterone in the male.
   1. GTRH is produced by the hypothalamus.
3. Both hormones acting on the ovary and testes:
   1. In female FSH stimulate 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 where it gives midcycle surge.
      3. LH stimulates the corpus luteum formation which supports an embryo in case of fertilization.
5. Menstrual cycle:
   1. Hypothalamus produces GTRH which acts on the anterior pituitary glands which produce LH and FSH.
   2. There are hormonal cyclical 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. Vagina and cervix are prepared to allow the transfer of the sperms.

phase of cycle	LH IU/L	FSH  IU/L	Progesterone	Estradiol
Early follicular phase	low	raised	low	low
Late follicular phase	High = 1.68 to 15	low = 1.37 to 9.9	lower limit = <50 ng/dL	high = 20 to 350 pg/mL
Mid cycle	Peak = 21.9 to 56.6	raised = 6.17 to 17.2	increasing	high = 150 to 750 pg/mL
Luteal phase	low = 0.61 to  16.3	low = 1.09 to 9.2	increasing = 300 to 2500 ng/dL	increasing = 30 to 450 pg/mL
Start of Next cycle	low	rising	rising	rising

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 sperms.
   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 then 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 then LH and FSH levels are low.

7. Spot urine test to detect LH surge is used to evaluate and treating infertility.
   1. This indicates the period when women are most fertile.
   2. LH surge precedes 24 hours of ovulation can be recognized easily.
   3. 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 for ovulation. There will be a surge in the LH level.
      1. The best sample is from 11 am to 3 pm.
8. LH surge gives 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.

 
Normal values

Source 1

Age	Male  mIU/mL	Female  mIU/mL
Prepubertal child
Cord blood	0.04 to 2.6	0.04 to 2.6
2 to 11 month	0.02 to 8.0	0.02 to 8.0
1 to 10 year	0.04 to 3.6	0.03 to 3.9
Puberty Tanner stage
1	0.04 to 3.6	0.03 to 3.0
2	0.26 to 4.8	0.10 to 4.1
3	0.56 to 6.3	0.20 to 9.1
4  to 5	0.56 to 7.8	0.50 to 15.0
Adult	1.24 to 7.8
	Follicular	1.68 to 15
	Ovulatory	21.9 to 56.6
	Luteal phase	0.61 to 16.3
	Postmenopausal	14.2 to 52.3
Urine 24 hours	Male IU/day	Female IU/day
Child 1 to 10 year	<1.0 to 5.6	1.4 to 4.9
Puberty Tanner stage
1	1 to 5	1 to 5
2	1.5 to 11	3 to 10
3	2.5 to 13	5 to 18
4	5 to 16	6 to 21
5	4 to 28	5 to 24
Adult	9 to 23	4 to 30 (non-midcycle)

Source 2

		IU/L
Male		1.24 to 7.8
Female
	Follicular	1.6  to  15
	Ovulatory phase	21.9 to 56.6
	Luteal phase	0.61 to 16.3
	Postmenopausal	14.2 to 52.3
Child	Male 1 to 10 years	0.04 to 3.6
	Female 1 to 10 years	0.03 to 3.9

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

Increased values of LH seen in:

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 LH seen in:

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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