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Testosterone Levels by Age

What does it mean by testosterone levels by age? This means that testosterone levels at diefferent stages of human beings do vary with age. The careful study of the age versus testosterone levels chart clearly indicates the trend in testosterone level by age. The level of testosterone serum normally fluctuates from normal, optimal and the average levels.

What is the test for testosterone levels?

Testosterone is an androgen, or a sex hormone, produced by both males and females. Testosterone is a formal name of this hormone. This hormone does exists in different forms in the blood. The different form are, total testosterone, free testosterone and bioavailable testosterone. It plays a very significant role in puberty and fertility.

The relevance for testosterone test in males and females is to determine the amount of testosterone hormone in the blood. The testosterone levels in the blood is normally measured in Nano grams per deciliter. This test is also known as serum testosterone test.

What is free testosterone in blood test?

Free testosterone test is used for measuring the amount of testosterone in the blood and is recorded Nano grams per deciliter (ng/dl). The test is also termed as a serum testosterone test.

Testosterone levels by age chart
Testosterone levels by age chart

About two-thirds of testosterone circulates in the blood bound to SHBG and slightly less than one-third bound to albumin. A small percentage of less than 4% circulates as free testosterone. Free testosterone plus the testosterone bound to albumin is the bioavailable testosterone, which can act on target tissues.

It is very important to note that, small fraction is albumin bound and a small proportion exists as free hormone. According to history, only the free testosterone was thought to be the biologically active component.

However, testosterone is weakly bound to serum albumin and dissociates freely in the capillary bed, thereby becoming readily available for tissue uptake. All non-SHBG-bound testosterone is therefore considered bioavailable.

Total testosterone test

Typically, a test for total testosterone is used for diagnosis. The total testosterone test measures testosterone that is bound to proteins in the blood, for example, albumin and sex-hormone binding globulin as well as free testosterone.

In many occasions, the total testosterone test gives reliable adequate information. However, in certain cases, for example when the level of Sex-hormone binding globulin is abnormal, a test for free or bioavailable testosterone may be performed as it may more accurately reflect the presence of a medical condition.

Bioavailable testosterone test

All the non-SHBG-bound testosterone is therefore considered bioavailable. Bioavailable testosterone test is online carried out when other tests may be insufficient for diagnosis of mild abnormalities of testosterone. In such a situation, additional measurements of free testosterone or bioavailable testosterone are recommended for better and accurate results.

Usually, bioavailable and free testosterone levels parallel the total testosterone levels. However, a number of conditions and medications are known to increase or decrease the SHBG (SHBG / Sex Hormone Binding Globulin [SHBG], Serum) concentration, which may cause total testosterone concentration to change without necessarily influencing the bioavailable or free testosterone concentration.

It should be noted that, while free testosterone can be used for the same indications as bioavailable testosterone, determination of bioavailable testosterone levels may be superior to free testosterone measurement in most cases.

Other hormone level tests

There are many other hormone level tests. However, the test will always depend on the relevance of it be carried out. Other tests and hormone levels may be done in conjunction with testosterone testing. Some examples include: SHBG, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), Estrogens, DHEAS, Prolactin, 17-Hydroxyprogesterone, and Androstenedione.

When is testosterone test relevant?

Testosterone is the main sex hormone in men, produced mainly by the testicles, and is responsible for male physical characteristics. Although this hormone is considered to be a “male” sex hormone, testosterone hormone is present in the blood of both males and females.Testosterone levels in men by age

Testosterone test is normally used to diagnose various conditions that commonly affect, men and women. Let’s take a look on the relevance of testosterone test in both males and females:

1. Relevance of testosterone test in men

Testosterone test is carried in men when infertility is suspected or when a man has a decreased sex drive or erectile dysfunction. Some other symptoms that may call for testosterone test are;

  • Lack of beard and body hair.
  • Decreased muscle mass, and development of breast tissue.
  • Erectile dysfunction.
  • Testicular tumors.

It is important to note that, low levels of total and bioavailable testosterone have also been associated with, or caused by, a greater presence of visceral fat, insulin resistance, and increased risk of coronary artery disease.

2. Relevance of testosterone test in boys

In boys characterized by delayed or slowly progressing puberty, testosterone test is often needed with the FSH and LH tests. Although there is variation in beginning of the puberty stage in boys, it is generally by the age of 10 years.

Testosterone test in boys can also be relevant when a young boy seems to be undergoing a very early puberty stage with obvious secondary sex characteristics. Causes of precocious puberty in boys, due to increased testosterone, include various tumors and congenital adrenal hyperplasia.

Other common symptoms of delayed puberty may include:

  • Delayed development of muscle mass
  • Lack of deepening of the voice or growth of body hair
  • Slow or delayed growth of testicles and penis
  • Delayed or early puberty in boys

3. Relevance of testosterone test in women

Testosterone levels in females can rise because of tumors that develop in either the ovary or adrenal gland or because of other conditions, such as polycystic ovarian syndrome. In females, testosterone testing may be done when a woman has the following symptoms:-

  • Irregular or no menstrual periods (amenorrhea),
  • Having difficulty getting pregnant
  • Females appearing to have masculine features, such as excessive facial and body hair,
  • Females having male pattern baldness, and/or a low voice.
  • Decreased sex drive in men and women
  • Infertility cases
  • Hypothalamus or pituitary disorders
  • Increased size of the clitoris
  • Decrease in the size of the breasts.

What does the test result mean?

Testosterone results in both males and females may be normal or abnormal.

1. Normal Testosterone Results

When carrying out testosterone level tests, normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different specimens. This means that, it is important to talk to your provider about the results obtained and their interpretation.

Below is a brief overview of normal testosterone results in males and females;


In males, testosterone test results should range from 300 Nano grams per deciliter up to 1,000 Nano grams per deciliter or else it should range from 10.41 to 34.70 Nano moles per liter for it to be normal.


Normal testosterone level test results ought to be ranging from 15 to 70 Nano grams per deciliter or range from 0.52 to 2.43 Nano moles per liter.

2. Abnormal testosterone results

Abnormal testosterone results normally arise due certain health conditions and medicines. Injuries can also lead to low testosterone. Testosterone level also naturally drops with age. Low testosterone can affect sex drive, mood, and the body in men.

Decreased total testosterone level

Decreased total hormones either in males or females is not something obvious. It is actually an alert that something somewhere is wrong. Below are some of the causes of decrease testosterone hormones in males and females;


In males, the decrease in testosterone levels indicate partial or complete hypogonadism. This is a condition where by, serum testosterone levels are usually below the normal range. The major cause of this condition may either be primary, secondary, tertiary or due to testicular failure.

Other causes of decreased total testosterone level in males may include:

  • Infection from a chronic illness
  • Failure of the pituitary glands to produce normal amounts of some or all of its hormones.
  • Males having problems with areas of the brain that control hormones
  • Low thyroid function
  • Delays of the puberty stage
  • Diseases such as, trauma, cancer, infection, immune that may affect the testicles
  • Having a benign tumor of the pituitary cells that produce too much of the hormone prolactin
  • Obesity


The decrease in testosterone levels may be observed in females due to primary or secondary ovarian failure, which is distinct to the situation in men, alongside the more prominent changes in female hormone levels. Most women with oophorectomy have a significant decrease in testosterone levels.

Increased total testosterone level

  • Resistance to the action of male hormones (androgen resistance)
  • Tumor of the ovaries
  • Cancer of the testes
  • Congenital adrenal hyperplasia
  • Taking medications or drugs that increase testosterone level

Testosterone levels by age

Testosterone is an essential hormone, it has the ability to regulate sex drive, sperm production, promote muscle mass, increase energy, and even influence human behavior. This hormone is also a natural part of aging in human beings.

Studies on testosterone levels by age indicates that, as men age, total testosterone levels decline. The worse part of it is that, free testosterone levels decline more rapidly that total testosterone. According to studies carried out, total testosterone normally decreases by 30% in health men of the age that range between 25 to75 years.

Testosterone levels in the womb

When in the womb, testosterone hormone plays a very important role in shaping the developing fetus during pregnancy. It drives the development of the male reproductive system. Testosterone also masculinizes the brain.

However, testosterone levels have to fall within a very narrow range in order for the fetal brain to be healthy. High levels of fetal testosterone may be linked to autism. Other research has found that low levels of fetal testosterone may boost your chances of getting Alzheimer’s disease later in life.

Testosterone levels in adolescents to early Adulthood

Testosterone levels are at their highest during adolescence and early adulthood. The initial visible signs of testosterone, or androgens, in the body are apparent during puberty.

In boys, the voice normally changes, shoulders broaden, and the facial structure becomes more masculine. But as men get older, their testosterone levels decline about 1 percent per year after age 30.

Optimal and normal testosterone levels in men and women

In summary, the optimal normal testosterone range in males is about 270 to 1070 ng/dl with an average level of 679 ng/dl.

A normal male testosterone level normally peaks up at the age of 20, the level then slowly declines. Testosterone levels above or below the normal range are considered by many to be out of balance.

Even so, when it comes to average testosterone levels, women naturally have much lower than men. According to the National Institutes of Health, the normal total testosterone range for a female is from 30 to 95 ng/dl. Free testosterone levels in women should be between 0.3 and 1.9 ng/dl.

Average testosterone levels by age

It should be kept in mind that testosterone levels do vary with age. However, the normal testosterone hormone range in women is 30 to 90 Nano grams per deciliter while in men it ranges from 300 to 1200 Nano grams per deciliter. In addition the average level of testosterone in males is 679 ng/dl.

Bioavailable testosterone range

When determining bioavailable testosterone range, it is good to note that, both free and albumin-bound testosterone are biologically active. The two are altogether referred to as the bioavailable fraction. Thus, bioavailable testosterone levels depend on albumin levels to a small extent and SHBG levels to a large extent.

Testosterone hormone injections

Injection refers to the act or process of forcing a liquid medicine or drug into someone or something by using a special needle. Therefore testosterone injections ae widely used for the treatment of various conditions in males and females.

In men and boys it is used for the treatment of conditions caused by the lack of this hormone. The lack of testosterone hormone in males in characterized by delayed puberty, impotence, or other hormonal imbalances. Such treatments are given in hormone therapy clinics such as the TRT Medical Center.

On the other hand, testosterone injection is also used in women for the treatment of breast cancer that has spread to other parts of the body.

How testosterone injections are administered

Knowing how to administer testosterone injection is very significant. This is because, misuse of testosterone can cause dangerous or irreversible effects, such as enlarged breasts, small testicles, infertility, high blood pressure, heart attack, stroke, liver disease, bone growth problems, addiction, and mental effects such as aggression and violence.

Therefore, testosterone hormone is injected into a muscle. The injection is usually given after every 2 to 4 weeks. However, for effectiveness and excellent use of testosterone injection, the following steps should be carefully adhered to:

1. Identify the concentration of the testosterone

Different testosterones normally have distinct concentrations. Some testosterone have twice as the concentrated as others. Before giving any injection, it is very important to make sure that the right dosage is used by taking into consideration its concentration.

2. Use a sterile needle and syringe.

Ensure that you use a sterile, never-before-used needle when administering testosterone. Dirty needles can spread deadly blood-borne diseases like hepatitis and HIV. For this reason, it is advisable to use a clean, sealed, capped needle every time you give a testosterone injection.

3. Wash your hands thoroughly and put on sterile gloves. 

To reduce the risk of infection, it is very important that you keep your hands clean when giving an injection. Therefore, wash your hands thoroughly with antibacterial soap and water, then put on sterile gloves.

However, if you accidentally touch any un-sterilized objects or surfaces before giving the injection, discard replace your gloves as a safety measure.

4. Draw up a dose. 

Draw up a dose as recommended by the doctor. Make sure that you determine the volume of your dose in relation to the concentration of your testosterone. To draw up your dose,

  1. First draw air into your syringe equal to the volume of your dosage.
  2. Then, wipe the top of the medication bottle with an alcohol wipe,
  3. Insert your needle through the lid and into the medication,
  4. And push the air from your syringe into the bottle.
  5. Turn the bottle upside down and draw out the exact dosage of testosterone.

5. Switch to a smaller needle. 

Thick needles can be fairly painful. There is no need to subject yourself to this extra pain, especially if you’re on a program that calls for frequent injections. To switch to a smaller needle once you’ve drawn up your dose,

  1. Remove the needle from the bottle and hold it point-up in front of you.
  2. Draw a small amount of air – this is to put space between the medicine and the top of the syringe so that you don’t spill.
  3. Using the hand that is not holding the syringe, carefully re-cap and unscrew the needle, then replace it with a thinner one.

6. Aspirate the syringe. 

Injecting air bubbles into a person’s body can cause a serious medical condition called an embolism. Because of this, it’s very important to ensure there are no air bubbles in the syringe when you inject the testosterone.

Side effects of testosterone injections

However, it should be made clear that, testosterone hormone cannot be used to enhance athletic performance and should not be used for that purpose. When receiving testosterone injections, it is advisable to take blood tests frequently.

In addition to that, there are is a risk for using testosterone injections. It can significantly affect bone growth in boys who are treated for delayed puberty. Therefore, bone development may need to be checked with x-rays every 6 months during this treatment.

7. Prepare the injection site. 

Testosterone injections are typically given directly into a muscle. Two relatively easy and accessible sites for intramuscular injection are the top outside region of the thigh or the upper back portion of the thigh called the butt cheek.

8. Inject

Hold your loaded syringe like a dart at a 90 degree angle above the sterile injection site. Quickly plunge it into the flesh. Before depressing the plunger, draw back on it slightly. If you draw blood into the syringe, remove the needle and choose a different spot, as this means you’ve hit a vein. Inject the medication at a steady, controlled pace.

9. Care for the injection site post-injection

Once you have fully depressed the plunger, slowly pull the needle out. Press around the injection site with a sterile cotton swab as you do so – this prevents the emerging needle from pulling on the skin and causing extra pain. Assess the needle entry point for bleeding, and apply a sterile Band-Aid or cotton swab if needed.

Sources and references

  1. Lab Tests Online: Testosterone
  2. ELITE MEN’S GUIDE: Testosterone Levels by Age
  3. ELITE MEN’S GUIDE: Testosterone injections
  4. MedlinePlus: Testosterone
  5. MAYO CLINIC: Testosterone, Total, Bioavailable, and Free, Serum
  6. Wiki How: How to Give a Shot of Testosterone

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