- 0 — 5 months: 75 — 400 ng / dl
- 6 months — 9 years: 7 — 20 ng / dl
- 10 — 11 years: 7 — 130 ng / dl
- 12 — 13 years: 7 — 800 ng / dl
- 14 years: 7 — 1,200 ng / dl
- 15 — 16 years: 100 — 1,200 ng / dl
- 17 — 18 years: 300 — 1,200 ng / dl
- Adults: 240 — 950 ng / dl
- 0 — 5 months: 20 — 80 ng / dl
- 6 months — 9 years: 7 — 20 ng / dl
- 10 — 11 years: 7 — 44 ng / dl
- 12 — 16 years: 7 — 75 ng / dl
- 17 — 18 years: 20 — 75 ng / dl
- Adults: 8 — 60 ng / dl
- Men: 9 — 30 ng / dl
- Women: 0.3 — 1.9 ng / dl
- 20 — 29 years: 83 — 257 ng / dl
- 30 — 39 years: 72 — 235 ng / dl
- 40 — 49 years: 61 — 213 ng / dl
- 50 — 59 years: 50 — 190 ng / dl
- 60 — 69 years: 40 — 168 ng / dl
(Attention, the reference intervals may differ from one laboratory to another, therefore refer to those present on the report in case of blood and urine tests.)
Testosterone is the most important androgenic steroid hormone and is responsible for it
- in the man of the development of the genital organs and secondary sexual characteristics (beard, hair, timbre of the voice, musculature),
- while in women it acts as a precursor for the synthesis of an important female hormone (estrogen).
In both sexes, it then shows an anabolic effect (stimulation of the synthesis of new proteins with consequent increase in muscle mass) and is the cause of an important impact on the behavior model (also, but not only, on sexual desire).
In man it is mainly produced by Leydig cells, present in the testes, while in women the production takes place in the ovaries (especially in fertile age); production is stimulated and controlled by the luteinizing hormone (LH), synthesized by the pituitary gland: as the LH increases, the production of testosterone decreases.
The test measures the concentration of this hormone in a blood sample.
Testosterone circulates in free (1-4%) and bound (98% approximately) blood. The latter can be partly linked to albumin (38%), the main plasma protein, or to a specific binding protein, namely SHBG, sex hormone-binding globulin (60%), also called SSBG, i.e. sex steroid-binding globulin.
The bond between the hormone and albumin is not very strong and can be easily broken, therefore the expression bioavailable testosterone (BAT) refers to the sum of the free testosterone and that related to albumin.
It is believed that the bioavailable fraction represents the part of the circulating hormone that enters the cells more easily and better reflects the bioactivity than the pure measure of the total quantity.
We also remind that the variation of the SHBG levels can cause inaccuracies in the measurement of the bioavailable concentration.
- The decrease in the level of SHBG can be found in the case of obesity, hypothyroidism, during the use of androgens and in nephrotic syndrome.
- SHBG increases in the case of cirrhosis, hyperthyroidism and the use of estrogen. In these situations, the measurement of free testosterone may be more indicative.
In many cases the measurement of the total quantity gives the doctor all the information he needs, however, in certain cases (for example if there is an anomaly of the level of the SHBG), the bioavailable testosterone test can be performed which can diagnose any disease more precisely.
In adult men, testosterone levels play a fundamental role in relation to
- sexuality and fertility (regulates sexual desire and allows sperm maturation),
- skeletal muscle system (prevents osteoporosis),
- cardiovascular health (represents a protective factor against various metabolic diseases, such as high blood pressure and diabetes ).
It is also used as a drug, in both men and women, in case of deficiency.
In childhood, excessive testosterone production can cause the onset of early puberty.
In adults, a slight increase is generally asymptomatic (without symptoms); more important increases can be a sign of cancer and as such, the result will be investigated.
In the case of values lower than normal, there is generally hypogonadism, which can manifest itself with alteration of sexual characteristics (for example impotence) and reduced fertility. In these cases we speak of:
primary hypogonadism, when associated with an increase in LH and FSH levels, linked to causes:
- genetic (e.g. Klinefelter syndrome),
- development (testicle retained),
- ischemia (blockage of blood flow due for example to testicular torsion),
- infections (in the past, for example, a big risk was represented by mumps/mumps),
- autoimmune diseases,
- metabolic diseases (e.g. liver failure),
- orchiectomy (removal of testicles);
- secondary/tertiary hypogonadism, associated with normal LH / FSH levels:
- hypothalamic problems,
- pituitary problems,
- excess exercise,
- some substances of abuse such as cannabis.
During childhood, excessive testosterone production can cause masculinization in girls.
In adulthood, it can instead manifest itself in the form of
- appearance of hair (hirsutism),
- menstrual irregularities,
- fertility problems.
This condition is often part of a more general when of polycystic ovary syndrome, more common in overweight women; it can also be caused by
- tumor of the ovaries or adrenal glands,
- congenital adrenocortical hyperplasia.
A decrease in concentrations compared to the reference values instead causes more nuanced symptoms, such as a decrease in sexual desire and alterations in mood; it may be due to ovarian failure.
- Bilateral cryptorchidism
- Myotonic dystrophy
- Kidney failure
- Congenital adrenal hyperplasia
- Late puberty
- Down syndrome
- Klinefelter syndrome
- Celiac disease
- Molar pregnancy
- Female obesity
- Polycystic ovary
- Early puberty comprar trenabol 75
- Cushing’s syndrome
- Reifenstein syndrome
- Androgen-secreting tumor
- Adrenal tumor
- Ovarian tumors
(Attention, non-exhaustive list. It is also underlined that often small variations from the reference intervals may not have clinical significance.)
Factors influencing the exam
- In young men, the level measured in the early morning hours is on average 50% higher than the measurement in the evening hours.
- The level can vary considerably depending on the day it is measured, and sometimes it even changes more quickly. The assessment of androgen levels should, therefore, be based on several measurements.
- An excessive increase can be linked to the use of anabolic steroids.
- In men, the values may decrease in the use of alcoholism and liver disease. Some types of medications, such as androgens and steroids, can also decrease androgen levels.
- The prostate cancer responds to androgens, so many men with prostate cancer at an advanced stage receiving treatment with drugs that decrease testosterone levels.
- Drugs such as anticonvulsants, barbiturates, and clomiphene (ClomidВ®) can increase the concentration of the hormone. Women on estrogen therapy may have higher than normal values.
- It increases after exercise and decreases with age (over 40 years it tends to decrease annually by 1%).
When the exam is requested
In many cases, this test is prescribed together with those of FSH and LH to children in whom development occurs late or does not progress. Not all boys start developing at the same time, but development usually starts before the age of 10. Symptoms of delayed puberty include:
- delay in the development of muscle mass,
- voice that does not lower and hair that does not grow,
- penis and testicles that do not develop or develop too slowly.
The examination can also be prescribed in case of precocious puberty, with a too rapid development of secondary sexual characteristics (beard, hair, adult voice, …). Among the causes of early puberty, we mention different types of cancer and congenital adrenal hyperplasia.
Other alarm bells include lack of beard and hair, decrease in muscle mass and gynecomastia (i.e. breast development). The total and bioavailable testosterone deficiency was also linked to the greater presence of visceral adipose tissue (visceral fat or intra-abdominal fat) and to the increased risk of coronary artery disease.
In women, the examination can be prescribed in case of menstrual irregularities or amenorrhea (absence of menstruation), problems with getting pregnant or male sexual characteristics, such as excess hair, baldness, acne, and / or lowering of the voice. The level may increase due to tumors that develop in the ovaries or adrenal glands, or for other diseases, such as PCOS (polycystic ovary syndrome).
No preparation is required.
The hormone peaks during adolescence and the early stages of adulthood. As we age, the amount gradually decreases, usually about 1% per year after the age of 30. In older men, it is important to understand whether testosterone deficiency is caused by aging or by a disease (hypogonadism).
Testosterone therapy (with patches or injections) is able to increase the amount of the hormone in the body. It can be useful to relieve some symptoms and / or prevent the loss of muscle and bone tissue that accompanies aging. The benefits of therapy, however, have not yet been conclusively proven. Experts, in fact, fear that hormone replacement therapy may aggravate prostate cancer, but no research has so far shown that such therapy can cause cancer. Those suffering from erectile dysfunction may have a hormone deficiency, but in many cases, the administration of testosterone does not improve the symptoms because there are other pathologies upstream.
Replacement therapy offers many fascinating possibilities:
- can increase muscle mass,
- improve memory and concentration,
- improve libido,
- Increase in energy.
but the health benefits offered by replacement therapy are not so clear.
What are the risks?
Testosterone therapy has several risks, for example, it can:
- increase the risk of developing sleep apnea, a potentially serious sleep disorder in which breathing stops and resumes several times during the night’s sleep,
- make the body produce too many red blood cells (polycythemia), increasing the risk of heart disease,
- cause acne or other skin reactions,
- cause benign prostatic hyperplasia (a benign increase in the size of the prostate) and perhaps also the growth of prostate tumors,
- increase breast size,
- limit the production of sperm or contract the testicles.
If you think replacement therapy is right for you, ask your doctor what the risks are and what the benefits are. Therapy may be necessary if there is a condition that decreases the concentration of circulating hormone, but currently, it is not advisable to treat the normal problems associated with aging with testosterone.
Is the amount of hair directly proportional to that of testosterone?
Research has shown that there is a proportionality between the amount of hormone and that of the hair, but the growth is different in the various parts of the body; for example in some men the hormone makes the hair grow on the abdomen and on the back, but not on the scalp, causing baldness. Genetic factors are primarily responsible for the expression of the 5-alpha reductase enzyme, which converts testosterone into dihydrotestosterone, causing family predisposition to baldness. Finasteride (PropeciaВ®) is a drug that inhibits the action of 5-alpha reductase and can resolve the balding tendency in some men.