We educate men on how they can 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 merely as a hormone, plays an essential and far-reaching role in men's health. This blog post is aimed at men who want to understand the importance and effects of their testosterone levels on their overall health. Our goal is to explain the complexity and medical terminology associated with testosterone tests in an understandable and actionable way. We highlight 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 health status. With a detailed explanation of what normal, low, and high testosterone levels mean at different stages of life, we want to provide you with the knowledge to correctly contextualize and understand your test results. This way, you are best prepared to actively manage and improve your hormonal health.
How testosterone affects your health
Testosterone plays a key role in many areas of men's health. A balanced testosterone level can have a positive effect 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 an 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. An optimal testosterone level is often associated with a sense 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 a decrease in 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 building and muscle strength. A healthy testosterone level promotes muscle building 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 bone fractures, especially in old 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 an essential role in the bodies of both men and women, although men produce larger amounts (Nassar & Leslie, 2023). This hormone is produced by the testes in men, the ovaries in women, and the adrenal glands, which are located above the kidneys (Vierhapper et al., 1997). In our blood, there are different forms of testosterone that can be measured to diagnose certain health problems. The majority of testosterone is bound to proteins (Bhasin et al., 2017). These proteins prevent the testosterone from being immediately used by the tissue, which controls the amount of "active" testosterone in the body. Testosterone that is not bound to proteins is called free testosterone and acts directly on the tissue.
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, makes it necessary to perform these tests multiple times (Bassil et al., 2009). A one-time measurement of testosterone levels often only provides a snapshot that may not reflect the true hormonal landscape. Multiple blood tests, on the other hand, provide a dynamic and more comprehensive picture of hormone status and are therefore crucial for a correct diagnosis and subsequent treatment planning.
Free vs. Total Testosterone
Understanding the difference between free and total testosterone is essential to correctly interpret your testosterone levels. These two parameters provide deep insights into your hormonal health and are crucial for targeted treatment in the event of a testosterone imbalance.
- Total testosterone: This value includes all the testosterone in your blood. This includes both protein-bound testosterone and free testosterone. The majority of testosterone in the blood is bound to proteins, approximately 98-99% – mainly to sex hormone-binding globulin (SHBG) and to a lesser extent to albumin (Bhasin et al., 2017). This binding to proteins 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 part is biologically active and can be directly used by the body's cells. Free testosterone makes up only a small fraction of total testosterone, but it is extremely important because it triggers the immediate physiological effects of the hormone. A test for free testosterone can provide deeper insights into possible symptoms of testosterone deficiency, especially if total testosterone shows normal values. A direct measurement of free testosterone is often not necessary, as a relatively accurate estimate can be achieved through 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 values, 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 advisable to consider both values as part of a comprehensive assessment of testosterone function in the body. Especially with symptoms such as fatigue, reduced libido, or loss of muscle strength, determining free and total testosterone, possibly supplemented by further hormone tests, can provide important information. At Adon Health, these circumstances are appropriately taken into account for the precise medical assessment of your complaints.
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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) to achieving and maintaining erections, to bone health and the production of red blood cells (Meinhardt, 2010). Therefore, it is crucial to maintain normal testosterone levels, which vary from person to person.
The goal is overall well-being. Not everyone who has low testosterone levels experiences symptoms. The effects vary depending on the individual, age, size, and physical fitness. Testosterone produced in the testes decreases 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 shown 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 approximately 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 values, or the age-related decline in testosterone levels. Your doctor will, however, take this into account when interpreting your values. If your testosterone level is below 12.1 nanomoles per liter (nmol/L) and you show symptoms, testosterone replacement therapy (TRT) could be beneficial for you (Male Hypogonadism - UROweb, n.d.).
A study from 2022 examined the testosterone levels of 1,486 men aged 20 to 44 (Zhu et al., 2022). To calculate the normal testosterone level for each age group, the middle third was used and classified as normal results according to the definition of the American Urological Association.
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 range as normal, these normal ranges may be too narrowly defined. With the availability of further data, it is likely that the reference ranges for testosterone will be improved to include age-specific values. However, what is more important is the overall trend of your testosterone level and whether you have 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 found (Zitzmann et al., 2006) 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 could make sense 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 if his values are outside the normal range. Often, in such a case, switching to a healthier lifestyle is sufficient to naturally improve testosterone levels.
The decision to start testosterone replacement therapy (TRT) depends on the result of your assessment with your doctor. The following thresholds of the European Association of Urology (EAU) (Male Hypogonadism - UROweb, n.d.) could help you understand your results better:
- Testosterone levels above 12 nmol/L generally do not require treatment.
- Testosterone levels between 8 and 12 nmol/L may require testosterone replacement therapy (TRT) if symptoms of testosterone deficiency are present. In these cases, it makes sense to check the free testosterone level, often together with other male sex hormones.
- Testosterone levels below 8 nmol/L normally require treatment.
In some cases, testosterone levels may be within the normal range, but symptoms of testosterone deficiency may still be present. In these cases, it makes sense to include further laboratory parameters in the assessment, including free testosterone (fT), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and sex hormone-binding globulin (SHBG). These are further hormones or blood proteins whose determination is essential for a comprehensive assessment of the sex hormone status in men.
Case Study: Lukas Finally Wanted to Know What Was Going On With Him
Lukas is 43 years old, married, a father of two children, and heavily involved in his professional life. For months, he felt like he was held back. In the mornings, he had difficulty getting out of bed, although he regularly slept seven to eight hours. In everyday life, he lacked motivation, was often irritable in conversations, and during sports, he increasingly felt that his body was no longer properly cooperating. His libido had also greatly diminished.
Initially, Lukas thought this was a consequence of stress. Maybe just too much work, too few breaks, the typical burdens of a hectic life. But the vague feeling that something was deeply wrong remained.
He decided to have a blood test to be sure. The doctor had the total testosterone level determined. The result was 12.6 nanomoles per liter, a value that according to the laboratory reference was still within the normal range. The feedback: "Everything is fine."
For Lukas, it did not feel fine. The symptoms were real. And even if the number on paper was correct, it did not fit his everyday life. He wanted to know more precisely.
A subsequent more comprehensive hormone status finally shed light on the matter. In addition to total testosterone, free testosterone, SHBG, LH, and other values were also captured. The evaluation showed that although Lukas had enough total testosterone in his blood, the majority of it was bound to proteins. His free testosterone, the biologically active portion, was significantly below what would be functionally necessary. At the same time, his SHBG level was elevated, which additionally ensured that less testosterone could actually become effective.
For the first time, there was a tangible explanation for his complaints. He suffered from functional testosterone deficiency, despite seemingly "normal" laboratory values.
In a detailed conversation with his treating doctor, Lukas was able to understand the results in detail. For over 30 minutes, all the connections were explained to him clearly: why laboratory values alone are often not sufficient, what importance free testosterone and SHBG have, and how important it is to take symptoms seriously, even when the total testosterone level is still within the reference range. Lukas not only received a clear contextualization of his values, but also the medical knowledge to make a well-founded decision about the next steps together with the doctor.
"I thought for a long time that I was imagining it or was simply overwhelmed. Now I know that there is a medical reason. That has helped me enormously to take myself seriously again."
For Lukas, the diagnosis was not the end, but an important beginning. Finally, he understood what was going on with him. The years of uncertainty, the brooding, the frustration about his own bodily sensations—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 understand its effects on various aspects of life. The importance of testosterone extends far beyond physical health and also influences mental well-being, energy, sexual health, as well as muscle and bone strength. An understanding of the different testosterone levels and their effects is therefore essential for men to actively shape both their health and their quality of life.
It is important that testosterone levels are not viewed in isolation. The overall situation, including age, lifestyle, and general state of health, plays a crucial role in assessing hormonal health. This includes understanding the difference between free and total testosterone, where free testosterone is responsible for direct physiological functions, while total testosterone provides a comprehensive overview. Knowing what normal testosterone levels are for different age groups, and being aware of possible symptoms of testosterone deficiency, enables men to make better-informed decisions about their health. This can be particularly important when considering whether testosterone replacement therapy (TRT) is a suitable treatment option.
At Adon Health, the focus is on comprehensively educating and supporting men about their hormonal health. With a deep understanding of the various factors influencing testosterone levels and the resulting health conditions, Adon Health offers consultation and treatment options that are specifically tailored to the needs of each individual man. This enables individual paths to a balanced and healthy life.
