Introduction
Testosterone is a hormone primarily synthesized in males within the testicles and in females within the ovaries. However, it is also present in smaller amounts in other body tissues. It is a steroid hormone that belongs to the class of androgens, which promotes the development of male sexual characteristics.
What Is the Physiological Role of Testosterone?
Testosterone plays a critical physiological role in both males and females.
- In males, testosterone is pivotal for the development of masculine sexual characteristics, including the deepening of the voice, the growth of facial and body hair, the augmentation of muscle mass, and the enhancement of bone density. It also plays a crucial role in the production of sperm and the regulation of sex drive (libido).
- In females, testosterone is also important for maintaining bone density and muscle mass, and it also contributes to sex drive and overall health. Both males and females rely on testosterone to support the production of red blood cells, which, in turn, facilitates the transportation of oxygen to tissues across the body.
As individuals age, testosterone levels naturally decrease in both males and females, which can give rise to various health concerns. In males, reduced testosterone levels can contribute to a decrease in muscle mass, bone density, and sex drive, as well as erectile dysfunction. Similarly, females may experience decreased muscle mass, decreased bone density, and a decrease in sex drive due to low testosterone levels.
What Are the Normal Levels of Testosterone?
Normal testosterone levels can vary depending on age and gender.
For Adult Males:
- The normal range for total testosterone is between 300 and 1000 ng/dL (nanograms per deciliter).
- The normal range for free testosterone is between 50 and 250 pg/mL (picograms per milliliter).
For Adult Females:
- The normal range for total testosterone is between 15 and 70 ng/dL.
- The normal range for free testosterone is between 1 and 8 pg/mL.
Generally, the following ranges are considered normal for total testosterone levels in adults:
- Men: 300 to 1,000 ng/dL.
- Women: 15 to 70 ng/dL.
What Is a Testosterone Levels Test?
A testosterone levels test is a medical test that measures the amount of testosterone present in a person's blood. This test is typically used to diagnose conditions related to testosterone levels, such as hypogonadism, which is a condition characterized by low testosterone levels.
Typically, the test involves taking a blood sample from the subject's arm and submitting it to a lab for evaluation. In order to ensure reliable findings, the blood sample is often taken in the morning when testosterone levels are at their peak. The subject may also be given specific instructions regarding what to avoid doing or taking before the test.
What Are the Different Types of Testosterone Level Tests?
The following are the three primary testosterone blood test types:
1. Total Testosterone Test: This test measures the total amount of testosterone in the blood, including free and testosterone bound to proteins. The test is commonly used to diagnose conditions related to testosterone levels, such as hypogonadism, and is usually performed in the morning when testosterone levels are highest. This is the most common type of testosterone test and provides a general picture of a person's overall testosterone levels.
2. Free Testosterone Test: This test measures the amount of testosterone that is not bound to proteins in the blood, also known as the "active" form of testosterone. This type of testosterone is not bound to proteins and is available for use by the body's tissues. Free testosterone is thought to be a more accurate reflection of a person's testosterone levels, as it is the form of testosterone that is most active in the body. However, free testosterone levels can be affected by factors such as age and health conditions, and the test may not always be accurate.
3. Bioavailable Testosterone Test: This test measures the amount of free testosterone and testosterone that is loosely bound to a blood protein called albumin. This form of testosterone is also available for use by the body's tissues and is thought to be a more accurate reflection of a person's overall testosterone levels than the total testosterone test. However, this test is not commonly done and may not be necessary in all cases.
What Is the Purpose of the Testosterone Levels Test?
Here are some particular reasons for a doctor to request a testosterone test:
- Hypogonadism: This is a condition in which the body produces abnormally low levels of testosterone. Symptoms of hypogonadism in men can include low sex drive, decreased muscle mass, fatigue, and erectile dysfunction. In women, symptoms include irregular periods, decreased sex drive, and fatigue.
- Infertility: Testosterone is important for the production of sperm in men, and low testosterone levels can contribute to infertility. A testosterone levels test may be ordered to assess a man's fertility if he has difficulty conceiving with his partner.
- Prostate Cancer: Reducing testosterone levels is often a component of prostate cancer treatment due to the potential of testosterone to stimulate the growth of cancer cells in the prostate. A test to measure testosterone levels can be utilized to assess the efficacy of prostate cancer treatment.
- TRT: Hypogonadism and other diseases associated with low testosterone levels are occasionally treated with testosterone replacement treatment (TRT). To track the results of TRT and make sure that testosterone levels are within a healthy range, a test of testosterone levels may be used.
When Is the Testosterone Levels Test Advised?
A testosterone level test may be advised by a healthcare provider if a person is experiencing symptoms that suggest a hormone imbalance or a condition related to testosterone levels.
Some of the common signs and symptoms that may prompt a healthcare provider to order a testosterone levels test include:
In Men:
- Decreased sex drive.
- Erectile dysfunction.
- Decreased muscle mass.
- Fatigue.
- Depressed mood.
- Loss of body hair.
- Infertility.
In Women:
- Irregular periods.
- Decreased sex drive.
- Fatigue.
- Infertility.
What Is the Inference of Testosterone Levels Test Results?
Generally, the test measures the amount of testosterone in a person's blood, and the results may indicate whether the levels of this hormone are within a normal range or if there is a deficiency or excess.
Total testosterone levels below 300 ng/dL in men and below 15 ng/dL in women may indicate low testosterone levels.
If the results show low testosterone levels, it may suggest a medical condition affecting testosterone production or distribution, such as
- Pituitary gland disorder.
- Injury to the testicles.
- Alcohol use disorder.
- Genetic disorders like Klinefelter syndrome.
Total testosterone levels above 1,000 ng/dL in men or above 70 ng/dL in women may be considered high.
High testosterone levels may indicate:
In Men-
- Tumor in the testicles.
- Steroid use.
- Adrenal gland disorders like congenital adrenal hyperplasia (CAH).
In Women-
- Polycystic ovary syndrome (PCOS).
- Ovarian cancer.
- Adrenal gland disorders.
Conclusion
In conclusion, testosterone plays a critical role in various bodily functions, and blood tests can be used to measure testosterone levels. However, a testosterone levels test alone cannot diagnose any health conditions, and abnormal results should be interpreted in conjunction with other factors such as medical history, symptoms, and physical examination. Seeking guidance from a healthcare provider is crucial as they can interpret the test results and offer suitable treatment options if needed.
