Testosterone Total, and Free Testosterone
Testosterone
Sample for Testosterone
- It is done in the serum.
- Can use heparinized plasma.
- 24 hours of the urine sample.
- Separate the serum immediately; if kept for a longer period (more than 6 hours), may get false high values.
- The sample is stable at 1 to 4 °C for one week.
- Free Testosterone is stable for 1 to 2 days at 4 °C.
- At -20 °C sample is stable for 6 months.
Precautions for Testosterone estimation
- Separate serum from the cells within 6 hours; otherwise, there is a false value elevation.
- The level is high in adults in the AM sample and 25% lower in the evening sample.
- In females, lower values increase 1 to 2 days mid-cycle.
- High values after the exercise.
- Value is decreased after the overload with glucose.
- There is a slow progressive decrease after the age of 50 years.
Purpose of the test (Indications) for Testosterone level
- In males, this test is done to evaluate the following:
- Hypogonadism.
- This stimulation can be done by giving clomiphene and HCG.
- Cryptorchidism.
- Impotence.
- Pituitary gonadotropic function.
- Infertility.
- Precocious puberty.
- Tumor marker for the testicular tumors.
- Hypogonadism.
- In the female, this test is done to assess:
- Hirsutism and virilizing syndrome.
- Ambiguous sex character.
- Precocious puberty.
- Tumor marker for ovarian tumors.
- Maybe part of the fertility workup of the chronic anovulatory cycle due to the polycystic ovary.
Pathophysiology of Testosterone
- Testosterone is the main androgen secreted by the testes, and its production increases by puberty.
- Women only produce 5% to 10% of the testosterone as much as males.
- Androgenic hormone includes:
- Dehydroepiandrosterone (DHEA).
- Androsterone.
- Testosterone.
- The adrenal gland produces DHEA, Cortisol, Aldosterone, and Testosterone.
- Testes produce DHEA.
- Ovaries produce DHEA.
- DHEA is a precursor of the Androstenedione precursor of Testosterone and estrogen.
- Testosterone is responsible for the development of male secondary characters.
Testosterone secretion:
- In men, testosterone is secreted by:
- Adrenal glands produce 2/3 of the total testosterone.
- Testes produce 1/3 of the total testosterone.
- In females, testosterone is secreted by:
- The adrenal gland is the source of all testosterone in females.
- Ovaries also produce some testosterone.
- Testosterone fluctuation in the level.:
- In the male, there is a peak level early in the morning.
- The female has cyclic elevation for 1 to 2 days around mid-cycle.
- Testosterone is made by:
- In males, mainly by the Leydig cells, which is almost 95 % of the total.
- In female :
- About 50 % is made by converting DHEA into fatty tissue.
- 30% conversion of DHEA in the adrenal glands.
- 20% is made directly by the ovaries.
The pituitary gland role in testosterone:
- The pituitary gland produces LH in males and FSH in females.
- LH stimulates the Leydig cells to produce Testosterone.
- FSH Stimulates Sertoli cell to help in spermatogenesis.
Testosterone functions:
- Testosterone stimulates spermatogenesis and secondary sex character.
- Testosterone Increased production is seen in:
- In Male produces premature puberty.
- In Females produce masculinity (manifested by amenorrhea and excessive growth of body hairs).
- Testosterone exists in two forms in the serum:
- In males:
- Circulating testosterone is bound to:
- 60% to 65% strongly bound to sex hormone-binding globulin (beta-globulin).
- 20% to 40% is bound to serum albumin.
- 1% to 2% testosterone is free or unbound testosterone. This is the only biologically active testosterone.
- Circulating testosterone is bound to:
- In females:
- Abound fraction consists of:
- 1% is free testosterone.
- 80% bound to sex hormone-binding globulin (SHBD).
- 19% bound to albumin.
- The free fraction is 2% unbound to the sex hormone globulin and albumin.
- Abound fraction consists of:
- Total testosterone = Bound fraction + Free fraction.
- Free fraction is the Active form.
Testosterone metabolism:
- Testosterone is metabolized in the liver, and the main metabolites are:
- Androsterone.
- DHT (dihydrotestosterone).
- These are further metabolized into androstenedione and etiocholanelone.
- End metabolites are excreted through the kidneys.
- The main metabolites of adrenal, testicular, and ovarian hormones are secreted through the kidneys as 17-ketosteroids.
NORMAL Testosterone
Source 1
Testosterone Free
Age | pg/mL | |
Male | Female | |
Cord | 5 to 22 | 4 to 16 |
Newborn (1 to 15 days) | 1.5 to 31.0 | 0.5 to 2.5 |
1 to 3 month | 3.3 to 8.0 | 0.1 to 1.3 |
3 to5 month | 0.7 to 14.0 | 0.3 to 1.1 |
5 to 7 month | 0.4 to 4.8 | 0.2 to 0.6 |
Children | ||
6 to 9 year | 0.1 to 3.2 | 0.1 to 0.9 |
10 to 11 year | 0.6 to 5.7 | 1.0 to 5.2 |
12 to 14 year | 1.4 to 156 | 1.0 to 5.2 |
15 to 17 year | 80 to 159 | 1.0 to 5.2 |
Adult | 50 to 110 | 1.0 to 8.5 |
- To convert into SI units x 3.47 = pmol/L
Testosterone Total (blood)
Age | ng/dL | |
Male | Female | |
Cord | 13 to 55 | 5 to 45 |
Premature | 37 to 198 | 5 to 22 |
Newborn | 75 to 400 | 20 to 64 |
1 to 5 month | 1 to 177 | 1 to 5 |
6 to 11 month | 2 to 7 | 2 to 5 |
Children | ||
1 to 5 year | 2 to 25 | 2 to 10 |
6 to 9 year | 3 to 30 | 2 to 20 |
Puberty Tanner stage | ||
1 | 2 to 23 | 2 to 10 |
2 | 5 to 70 | 5 to 30 |
3 | 15 to 280 | 10 to 30 |
4 | 105 to545 | 15 to 40 |
5 | 265 to 800 | 10 to 40 |
Adult | 280 to 1100 | 15 to 70 |
Pregnancy | 3 to 4 x adult level | |
Postmenopausal | 8 to 35 |
- 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
- >50 years
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
- Serum level of testosterone :
- In male infants :
- By 2 weeks = around 25 ng/dL.
- BY 2 months = around 275 ng/dL.
- In female infants :
- By 2 weeks = around 25 ng/dL.
- By 2 months = Value decreases and remains low throughout early childhood.
Increased values of Total Testosterone are seen in the following:
- Male
- hyperthyroidism.
- Adrenal tumors.
- Adrenal Hyperplasia.
- Hypothalamic tumor, Pinealoma.
- Viral encephalitis.
- Testicular or extragonadal tumors where Leydig cells produce testosterone.
- Testosterone resistance syndrome.
- Female
- Adrenal neoplasm.
- Hilar cell tumor.
- Idiopathic Hirsutism.
- Trophoblastic disease during pregnancy
- Ovarian tumors
- Polycystic ovary.
Decreased Total testosterone value is seen in Males:
- Klinefelter syndrome.
- Pituitary failure leading to hypogonadism.
- Hypopituitarism may be primary or secondary.
- Orchiectomy.
- Delayed puberty.
- Down syndrome (trisomy 21).
- Cirrhosis.
- Cryptorchidism due to undescended testes.
Increased Free Testosterone is seen in Females:
- Hirsutism.
- Virilization.
- Polycystic ovaries.
Decreased Free Testosterone is seen in Males:
- Hypogonadism.
- Old age.
Questions and answers:
Question 1: What type of cell is the source of testosterone?
Question 2: Total testosterone is biologically active?