Testosterone

Sample for Testosterone

1. It is done in the serum.
2. Can use heparinized plasma.
3. 24 hours of the urine sample.
4. Separate the serum immediately; if kept for a longer period (more than 6 hours),  may get false high values.
5. The sample is stable at 1 to 4 °C for one week.
6. Free Testosterone is stable for 1 to 2 days at 4 °C.
7. At -20 °C sample is stable for 6 months.

Precautions for Testosterone estimation

1. Separate serum from the cells within 6 hours; otherwise, there is a false value elevation.
2. The level is high in adults in the AM sample and 25% lower in the evening sample.
3. In females, lower values increase 1 to 2 days mid-cycle.
4. High values after the exercise.
5. Value is decreased after the overload with glucose.
6. There is a slow progressive decrease after the age of 50 years.

Purpose of the test (Indications) for Testosterone level

1. In males, this test is done to evaluate the following:
   1. Hypogonadism.
      1. This stimulation can be done by giving clomiphene and HCG.
   2. Cryptorchidism.
   3. Impotence.
   4. Pituitary gonadotropic function.
   5. Infertility.
   6. Precocious puberty.
   7. Tumor marker for the testicular tumors.
2. In the female, this test is done to assess:
   1. Hirsutism and virilizing syndrome.
   2. Ambiguous sex character.
   3. Precocious puberty.
   4. Tumor marker for ovarian tumors.
   5. Maybe part of the fertility workup of the chronic anovulatory cycle due to the polycystic ovary.

Pathophysiology of Testosterone

1. Testosterone is the main androgen secreted by the testes, and its production increases by puberty.
   1. Women only produce 5% to 10% of the testosterone as much as males.
2. Androgenic hormone includes:
   1. Dehydroepiandrosterone (DHEA).
   2. Androsterone.
   3. Testosterone.
3. The adrenal gland produces   DHEA, Cortisol, Aldosterone, and Testosterone.

4. Testes produce DHEA.
5. Ovaries produce DHEA.
6. DHEA is a precursor of the Androstenedione precursor of Testosterone and estrogen.

7. Testosterone is responsible for the development of male secondary characters.

Testosterone secretion: 

1. In men, testosterone is secreted by:
   1. Adrenal glands produce 2/3 of the total testosterone.
   2. Testes produce 1/3 of the total testosterone.
2. In females, testosterone is secreted by:
   1. The adrenal gland is the source of all testosterone in females.
   2. Ovaries also produce some testosterone.

The pituitary gland role in testosterone:

1. The pituitary gland produces LH in males and FSH in females.
2. LH  stimulates the Leydig cells to produce  Testosterone.
3. FSH  Stimulates Sertoli cell to help in spermatogenesis.

Testosterone synthesis in the testes

Testosterone functions:

1. Testosterone stimulates spermatogenesis and secondary sex character.
2. Testosterone Increased production is seen in:
   1. In Male produces premature puberty.
   2. In Females produce masculinity (manifested by amenorrhea and excessive growth of body hairs).
3. Testosterone exists in two forms in the serum:
4. In males:
   1. Circulating testosterone is bound to:
      1. 60% to 65% strongly bound to sex hormone-binding globulin (beta-globulin).
      2. 20% to 40% is bound to serum albumin.
      3. 1% to 2% testosterone is free or unbound testosterone. This is the only biologically active testosterone.
5. In females:
   1. Abound fraction consists of:
      1. 1% is free testosterone.
      2. 80% bound to sex hormone-binding globulin (SHBD).
      3. 19% bound to albumin.
   2. The free fraction is 2% unbound to the sex hormone globulin and albumin.
6. Total testosterone = Bound fraction + Free fraction.
   1. Free fraction is the Active form.

Testosterone metabolism:

1. Testosterone is metabolized in the liver, and the main metabolites are:
   1. Androsterone.
   2. DHT (dihydrotestosterone).
   3. These are further metabolized into androstenedione and etiocholanelone.
   4. End metabolites are excreted through the kidneys.
2. The main metabolites of adrenal, testicular, and ovarian hormones are secreted through the kidneys as 17-ketosteroids.

NORMAL Testosterone

Source 1

Testosterone Free

• To convert into SI units x 3.47 = pmol/L

Testosterone Total (blood)

1. To convert into SI unit x 0.0347 = nmol/L

Urine

• 20 to 50 years
• Male   = 50 to 135 µg/day
• Female = 2 to 12 µg/day
  • >50 years
    • Male = 40 to 60 µg/day
    • Female = 2 to 8 µg/day

Source 2

Total testosterone

• Men = 3 to 10 ng/mL
• Women = <1 ng/mL
• Prepubertal boys and girls = 0.05 to 0.2 ng/mL

Source 4

Free testosterone

• Men = 50 to 210 pg/mL.
• Women = 1.0 to 8.5 pg/mL.
• Children:
  • Boy = 0.1 to 3.2 pg/mL.
  • Children Girl = 0.1 to 0.9 pg/mL.
• Puberty:
  • Boy = 1.4 to 156 pg/mL.
  • Puberty Girls = 1.0 to 5.2 pg/ml.

Total testosterone

• Men = 270 to 1070 ng/dL.
• Women = 15 to 70 ng/dL.
• Postmenopausal women = 8 to 35 ng/dL.
• Pregnant women = 3 to 4 ng/dL

Testosterone by age

1. Serum level of testosterone :
2. In male infants :
   1. By 2 weeks = around 25 ng/dL.
   2. BY 2 months = around 275 ng/dL.
3. In female infants :
   1. By 2 weeks = around 25 ng/dL.
   2. By 2 months = Value decreases and remains low throughout early childhood.

Increased values of Total Testosterone are seen in the following:

1. Male
   1. hyperthyroidism.
   2. Adrenal tumors.
   3. Adrenal Hyperplasia.
   4. Hypothalamic tumor, Pinealoma.
   5. Viral encephalitis.
   6. Testicular or extragonadal tumors where Leydig cells produce testosterone.
   7. Testosterone resistance syndrome.
2. Female
   1. Adrenal neoplasm.
   2. Hilar cell tumor.
   3. Idiopathic Hirsutism.
   4. Trophoblastic disease during pregnancy
   5. Ovarian tumors
   6. Polycystic ovary.

Decreased Total testosterone value is seen  in Males:

1. Klinefelter syndrome.
2. Pituitary failure leading to hypogonadism.
3. Hypopituitarism may be primary or secondary.
4. Orchiectomy.
5. Delayed puberty.
6. Down syndrome (trisomy 21).
7. Cirrhosis.
8. Cryptorchidism due to undescended testes.

Increased Free Testosterone is seen in Females:

1. Hirsutism.
2. Virilization.
3. Polycystic ovaries.

Decreased Free Testosterone is seen in Males:

1. Hypogonadism.
2. Old age.

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