Total Testosterone (T total, serum)
Why this test?
- delayed or premature puberty in boys
- decreased sex drive in men and women
- erectile dysfunction in men
- male and female infertility
- testicular tumor diseases of the hypothalamus or pituitary gland
In what cases is it prescribed?
- With delayed sexual development of boys.
- Puberty usually occurs at the age of 10 and hormonal and physical changes occur.
- Delayed development of muscle mass, lack of a low voice and body hair, slow growth of testicles and penis indicate a delay in sexual development.
- The reason is that the testicles do not produce enough testosterone, or that the pituitary gland does not synthesize the required amount of luteinizing hormone.
- The analysis can also be performed if the boy has premature sexual development with pronounced secondary sexual characteristics - the cause may be an increased level of testosterone due to various tumors or congenital hyperplasia of the adrenal glands.
- If infertility is suspected, low sex drive or erectile dysfunction in adult men - all this can be a consequence of low testosterone secretion. In case of violation of the regularity of menstruation, in case of problems with the onset of pregnancy or in case of masculine signs in women. Their testosterone content can increase due to tumors of the ovaries or adrenal glands, due to other diseases, for example, polycystic ovary syndrome.
Testosterone is a steroid hormone (androgen) produced in the Leydig cells, an endocrine tissue of the male testes. Its synthesis is stimulated and controlled by luteinizing hormone (LH), produced by the pituitary gland. Testosterone functions in a negative feedback loop: as testosterone levels increase, luteinizing hormone concentrations decrease, while increasing luteinizing hormone levels decrease testosterone levels.
The level of testosterone fluctuates throughout the day, its peak occurs in the morning (between 4 and 8 a.m.), and it reaches its lowest values in the evening hours (between 4:00 p.m. and 8:00 p.m.). In addition, its concentration increases after exercise and decreases with age. Almost two-thirds of circulating testosterone is bound to sex hormone-binding protein, while a little less than one-third is bound to albumin. Free testosterone is very little, about 1-4%.
Testosterone promotes the development of secondary sexual characteristics, such as penis enlargement, body hair growth, muscle mass development, and a low voice. It is produced in large quantities in adolescents during puberty, and already in adult men it regulates sexual instincts and maintenance of muscle mass. In men, testosterone is produced by the glands, in women - by the glands and in a small amount by the ovaries.