We educate men on how to understand and interpret their testosterone levels, and show the effects on various aspects of health such as mood, energy, libido, muscle strength and bone density.
Testosterone, often viewed simply as a hormone, plays a vital and far-reaching role in men's health. This blog post is for men who want to understand the significance and impact of their testosterone levels on their overall well-being. Our goal is to explain the complexity and medical terminology associated with testosterone testing in a clear and practical way. We'll explore how testosterone levels, which are more than just numbers, can profoundly influence a man's well-being and are shaped by numerous factors such as age, lifestyle, and overall health. By providing a detailed explanation of what normal, low, and high testosterone levels mean at different stages of life, we aim to equip you with the knowledge to properly interpret and understand your test results. This will empower you to actively manage and improve your hormonal health.
How Testosterone Affects Your Health
Testosterone plays a key role in many aspects of men's health. Balanced testosterone levels can have a positive impact on mood, energy, libido, muscle strength, and bone density (Zitzmann et al., 2006) . But what does it actually mean if your testosterone levels are outside the normal range?
- Mood and mental health: Testosterone significantly influences mood. A balanced testosterone level can contribute to a positive mood and increased quality of life, while an imbalance can lead to mood swings, depression, or reduced self-esteem (Hintikka et al., 2009) .
- Energy levels: This hormone plays a key role in regulating energy balance. Optimal testosterone levels are often associated with a feeling of vitality and increased energy, while a deficiency can often lead to chronic fatigue and a general feeling of lethargy (Zitzmann, 2020) .
- Libido and sexual health: Testosterone is crucial for sexual function and libido. Low testosterone levels can cause decreased sexual interest and problems with sexual performance, while healthy levels support sexual desire and health (Hintikka et al., 2009) .
- Muscle strength and mass: Testosterone is an important hormone for muscle growth and strength. Healthy testosterone levels promote muscle growth and maintenance, which is important for physical activity and overall health (The Physiological Society, 2019) .
- Bone density: Testosterone also helps maintain bone density. Low levels can increase the risk of osteoporosis and fractures, especially in advanced age (Fink et al., 2006) .
What is a testosterone test?
A testosterone test is a medical examination that measures the amount of testosterone in the blood. Testosterone, often referred to as the "male" sex hormone, plays a vital role in the bodies of both men and women, with men producing larger amounts (Nassar & Leslie, 2023) . This hormone is produced by the testes in men, the ovaries in women, and the adrenal glands, which sit above the kidneys (Vierhapper et al., 1997) . There are several forms of testosterone in our blood that can be measured to diagnose certain health problems. Most testosterone is bound to proteins (Bhasin et al., 2017) . These proteins prevent the testosterone from being immediately used by tissues, thus controlling the amount of "active" testosterone in the body. Testosterone that is not bound to proteins is called free testosterone and acts directly on tissues.
Measuring testosterone levels through blood tests is a common method for assessing hormonal health in men. However, the complexity of hormonal regulation in the body, influenced by numerous factors such as age, time of day, diet, and lifestyle, necessitates multiple tests (Bassil et al., 2009) . A single testosterone measurement often provides only a snapshot that may not reflect the true hormonal landscape. In contrast, multiple blood tests offer a dynamic and more comprehensive picture of hormone status and are therefore crucial for accurate diagnosis and subsequent treatment planning.
Free vs. Total Testosterone
Understanding the difference between free and total testosterone is essential for correctly interpreting your testosterone levels. These two parameters offer deep insights into your hormonal health and are crucial for targeted treatment of a testosterone imbalance.
- Total testosterone: This value encompasses all the testosterone in your blood. This includes both protein-bound and free testosterone. The majority of testosterone in the blood is bound to proteins, approximately 98-99% – primarily to sex hormone-binding globulin (SHBG) and, to a lesser extent, to albumin (Bhasin et al., 2017) . This protein binding influences how testosterone is transported in the body and how it acts. A total testosterone test is often the first step in assessing hormonal health.
- Free testosterone: Free testosterone is the portion of the hormone that is not bound to proteins. This portion is biologically active and can be used directly by the body's cells. Free testosterone constitutes only a small fraction of total testosterone but is extremely important because it triggers the hormone's immediate physiological effects. A free testosterone test can provide deeper insights into potential symptoms of testosterone deficiency, especially when total testosterone levels are normal. Direct measurement of free testosterone is often unnecessary, as a relatively accurate estimate can be obtained using a formula. For this estimate, it is sufficient to determine total testosterone as well as the two blood proteins SHBG and albumin (Vermeulen et al., 1999) .
Both testosterone levels, total testosterone and free testosterone, are therefore important indicators of your hormonal health. Their ratio to each other and their respective levels can help create a clearer picture of your hormonal balance and function. It is recommended to consider both values as part of a comprehensive assessment of testosterone function in the body. Especially in cases of symptoms such as fatigue, decreased libido, or loss of muscle strength, measuring free and total testosterone, possibly supplemented by other hormone tests, can provide important information. At Adon Health, these factors are taken into account for a precise medical evaluation of your symptoms.
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Why knowing your own testosterone level is so important
Testosterone is responsible for many important functions, from muscle building (The Physiological Society, 2019) and achieving and maintaining erections to bone health and red blood cell production (Meinhardt, 2010) . Therefore, maintaining normal testosterone levels, which vary from person to person, is crucial.
The goal is overall well-being. Not everyone with low testosterone levels experiences symptoms. The effects vary depending on the individual, their age, height, and physical fitness. Testosterone, produced in the testicles, declines with age. After your 30s or 40s, you can expect it to decrease by about 1 to 2 percent each year (Stanworth & Jones, 2008) . This process of slow but steady decline has been consistently demonstrated in several large epidemiological studies (Kaufman & Vermeulen, 2005 , Vermeulen et al., 1996) . According to another study, up to 40% of men over 45 are affected by testosterone deficiency (Mulligan et al., 2008) .
What testosterone level is normal for your age?
A normal testosterone level for adult men is between 12 and 35 nmol/L (350–1010 ng/ml). Most laboratories use similar reference ranges. However, these values do not take into account your symptoms, baseline levels, or the age-related decline in testosterone. Your doctor will consider these factors when interpreting your results. If your testosterone level is below 12.1 nanomoles per liter (nmol/L) and you are experiencing symptoms, testosterone replacement therapy (TRT) may be beneficial for you ( Male Hypogonadism - UROweb , nd) .
A 2022 study examined the testosterone levels of 1,486 men aged 20 to 44 (Zhu et al., 2022) . To calculate normal testosterone levels for each age group, the middle third was used and classified as normal results according to the American Urological Association's definition.
Age / Testosterone (nmol/L) / Testosterone (ng/dL)
20–24 / 14.2–19.3 / 409–558
25–30 / 14.3–19.9 / 413–575
30–34 / 12.4–17.3 / 359–498
35–40 / 12.2–16.5 / 352–478
40–44 / 12.1–16.4 / 350–473
Since this data defines the middle third of the range as normal, these normal ranges might be too narrow. With the availability of more data, it's likely that the reference ranges for testosterone will be refined to include age-specific values. More important, however, is the overall trend of your testosterone levels and whether you have any symptoms. If you have no symptoms but are at the lower end of the normal range, this could be normal for you.
A cross-sectional cohort study of 434 men (Zitzmann et al., 2006) found that symptoms were more likely when testosterone levels fell below the following thresholds:
- 15 nmol/L – reduced energy levels
- 12 nmol/L – weight gain
- 10 nmol/L – low mood
- 8 nmol/L – Erectile dysfunction
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When testosterone replacement therapy might be beneficial for you
A low testosterone level alone is not necessarily a cause for concern. For example, a 50-year-old man with a testosterone level of 8.5 nmol/l, but without symptoms, would probably not benefit from treatment, even though his levels are outside the normal range. Often, in such a case, simply adopting a healthier lifestyle is enough to naturally improve testosterone levels.
The decision to begin testosterone replacement therapy (TRT) depends on the outcome of your assessment with your doctor. The following threshold values from the European Association of Urology (EAU) ( Male Hypogonadism - UROweb , nd) may help you better understand your results:
- Testosterone levels above 12 nmol/L generally do not require treatment.
- Testosterone levels between 8 and 12 nmol/L may necessitate testosterone replacement therapy (TRT) if symptoms of testosterone deficiency are present. In these cases, it is advisable to check free testosterone levels, often along with other male sex hormones.
- Testosterone levels below 8 nmol/L usually require treatment.
In some cases, testosterone levels may be within the normal range, yet symptoms of testosterone deficiency may still be present. In these cases, it is advisable to include other laboratory parameters in the evaluation, including free testosterone (fT), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex hormone-binding globulin (SHBG). These are additional hormones or blood proteins whose measurement is essential for a comprehensive assessment of sex hormone status in men.
Case study: Lukas finally wanted to know what was wrong with him.
Lukas is 43 years old, married, a father of two, and very busy with work. For months, he had felt completely held back. He found it difficult to get out of bed in the mornings, even though he regularly slept seven to eight hours. He lacked motivation in his daily life, was often irritable in conversations, and increasingly felt that his body wasn't cooperating when he exercised. His libido had also decreased significantly.
At first, Lukas thought it was a result of stress. Perhaps simply too much work, too few breaks, the typical burdens of a hectic life. But the vague feeling that something deeper was wrong remained.
He decided to have a blood test done to be sure. The doctor ordered a total testosterone test. The result was 12.6 nanomoles per liter, a value that, according to the lab reference range, was still within the normal range. The feedback: "Everything is fine."
Lukas felt something wasn't right. The symptoms were real. And even if the number on paper was correct, it didn't match his everyday life. He wanted to know more.
A subsequent, more comprehensive hormone analysis finally shed light on the situation. In addition to total testosterone, free testosterone, SHBG, LH, and other values were also measured. The analysis showed that while Lukas had sufficient testosterone overall, most of it was bound to proteins. His free testosterone, the biologically active fraction, was significantly below what would be functionally necessary. At the same time, his SHBG level was elevated, which further reduced the amount of testosterone that could actually be used effectively.
For the first time, there was a tangible explanation for his symptoms. He suffered from a functional testosterone deficiency, despite seemingly "normal" lab results.
In a detailed consultation with his doctor, Lukas was able to fully understand the results. For over 30 minutes, all the connections were clearly explained to him: why lab results alone are often insufficient, the significance of free testosterone and SHBG, and the importance of taking symptoms seriously, even when total testosterone levels are still within the reference range. Lukas not only received a clear interpretation of his results but also the medical knowledge to make an informed decision about the next steps together with his doctor.
"For a long time, I thought I was imagining it or simply overwhelmed. Now I know there's a medical reason. That has helped me enormously to take myself seriously again."
For Lukas, the diagnosis wasn't the end, but an important beginning. He finally understood what was wrong with him. The years of uncertainty, the brooding, the frustration with his own body's signals—all of that gave way to a clear picture. Knowing that his symptoms had a comprehensible, hormonal origin brought him relief and a new sense of control over his own health.
Our conclusion, your knowledge
Testosterone, a key hormone in men's health, deserves careful consideration to fully grasp its impact on various aspects of life. Its importance extends far beyond physical health, influencing mental well-being, energy levels, sexual health, and muscle and bone strength. Therefore, understanding different testosterone levels and their effects is essential for men to actively manage both their health and quality of life.
It is important that testosterone levels are not considered in isolation. The overall situation, including age, lifestyle, and general health, plays a crucial role in assessing hormonal health. This includes understanding the difference between free and total testosterone, with free testosterone responsible for direct physiological functions, while total testosterone provides a more comprehensive overview. Knowing what normal testosterone levels are for different age groups and being aware of potential symptoms of testosterone deficiency allows men to make more informed decisions about their health. This can be particularly important when considering whether testosterone replacement therapy (TRT) is an appropriate treatment option.
Adon Health focuses on providing men with comprehensive education and support regarding their hormonal health. With a deep understanding of the various factors influencing testosterone levels and the resulting health conditions, Adon Health offers advice and treatment options specifically tailored to each man's individual needs. This enables personalized paths to a balanced and healthy life.
