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  • Writer's pictureKen Schafer

Testosterone: What Do the Numbers Mean?

Updated: Sep 14, 2023

Introduction


In my blog post, Decoding Testosterone: Bound, Free, and Bioavailable Explained, I delve into the intricacies of testosterone and its different forms. When assessing your testosterone levels, it is crucial to understand the distinctions between total, free, bioavailable, and bound testosterone.



Graphic of the testosterone molecule.
The Testosterone Molecule


When you undergo a testosterone test, it is important to ensure that your doctor doesn't solely rely on measuring your Total Testosterone, which is a common practice. Examining your Total Testosterone, Free Testosterone, and Bioavailable Testosterone levels is necessary. Additionally, tests for Sex Hormone Binding Globulin (SHBG) and Estradiol, a form of estrogen, are required.


For a more comprehensive picture, include tests for Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), Prolactine, and Albumin levels. These tests provide valuable insights into the functioning of your hormonal system.


Furthermore, other tests such as Liver Function tests, Kidney Function tests, Lipid Profile (cholesterol levels), and Complete Blood Count (CBC) might be necessary. These tests help identify underlying issues that could contribute to low testosterone or manifest as symptoms of low testosterone.


I will only discuss Total, Free, and Bioavailable Testosterone levels. However, it's important to recognize that the additional tests mentioned earlier are crucial in identifying potential causes and associated symptoms of low testosterone.


You Get Your Testosterone Tested


You ask for a Testosterone test, or your doctor thinks you need one. Typically this is done when the patient complains of erectile dysfunction because that is usually the only symptom that causes most doctors to suspect low testosterone. But there are many other symptoms of low testosterone (see below), which manifests differently from person to person.



Graphic of the effects of testosterone on the body.
What does Testosterone Do?


Looking over this list, you will probably notice these symptoms are common.


Some Typical Symptoms of Low Testosterone:

  1. Reduced Libido: A decrease in sexual desire or interest in sexual activity is a common symptom of low testosterone.

  2. Erectile Dysfunction: Difficulties achieving or maintaining erections can indicate low testosterone levels.

  3. Fatigue and Reduced Energy Levels: Low testosterone can lead to feelings of fatigue, low energy, and reduced motivation.

  4. Decreased Muscle Mass and Strength: Testosterone plays a crucial role in muscle development and maintenance. Low testosterone levels can contribute to muscle loss and decreased strength.

  5. Increased Body Fat: Low testosterone levels may be associated with increased body fat, particularly around the abdomen.

  6. Mood Changes: Individuals with low testosterone levels may experience mood swings, irritability, increased stress, or a general sense of low mood and depression.

  7. Decreased Bone Density: Testosterone is important for maintaining healthy bone density. Low levels of testosterone can increase the risk of osteoporosis and bone fractures.

  8. Cognitive Changes: Some studies suggest a potential link between low testosterone and cognitive decline, including difficulties with memory, concentration, and overall cognitive function.

  9. Decreased Hair Growth: Low testosterone levels can reduce body and facial hair growth.

  10. Sleep Disturbances: Individuals with low testosterone may experience sleep disruption, including insomnia or increased sleepiness.




You Get Test Results


So you get your results, and they will likely fall into specific ranges called “normal.” Unfortunately, the normal range varies from lab to lab because of variations in their testing methods. They will be something like the following.


  • Total Testosterone:

    • Normal range: Approximately 300 to 1,000 ng/dL (nanograms per deciliter) or 10.4 to 34.7 nmol/L (nanomoles per liter).

  • Free Testosterone:

    • Normal range: Approximately 9 to 30 ng/dL or 0.3 to 1.0 nmol/L.

  • Bioavailable Testosterone:

    • Normal range: Approximately 131 to 682 ng/dL or 4.5 to 23.6 nmol/L.

Typically your doctor will only look at the result for Total Testosterone, and if it’s above 300, they will tell you your results are “normal, and you're fine.


But Are you “Fine?”


Determining whether you are truly "fine" based solely on testosterone test numbers is not a straightforward answer. The numbers themselves don't reveal the complete story. To gain a comprehensive understanding, we must consider testosterone sensitivity, also known as androgen insensitivity.


Testosterone sensitivity is influenced by various factors, with testosterone receptors playing a crucial role. Think of hormones as keys and receptors as locks. When a hormone attaches to its corresponding receptor, it triggers specific events within the target cells.


Individuals can have different levels of testosterone receptor sensitivity. Some possess highly sensitive receptors, others have less responsive or insensitive receptors, but most people fall in the middle. Genetic testing is the only reliable way to determine your receptor sensitivity.


What are the implications of testosterone sensitivity?


Someone with low testosterone levels can still function well with high testosterone sensitivity. On the other hand, it's possible for someone to have high testosterone levels and still require even higher levels to function optimally. Again, the majority of people typically fall somewhere in between these extremes.


By recognizing the significance of testosterone sensitivity, we understand that it complements the information provided by testosterone test results. It explains why two individuals with the same testosterone levels can experience different outcomes or symptoms.


While this delves into a more nuanced aspect of testosterone, understanding the interplay between hormone levels and receptor sensitivity sheds light on individual variations in response and helps guide personalized treatment approaches.


What Does “Normal” mean?


When we talk about "normal" in the context of testosterone levels, it's important to understand that it is determined statistically. In statistical terms, "normal" refers to falling within two standard deviations of the mean or average value. Approximately 68% of people will have testosterone levels within one standard deviation, and about 95% will fall within two standard deviations of the mean.


It's crucial to note that the term "normal" does not imply "healthy" or "asymptomatic." The definition is based on statistical distribution and does not correlate with an individual's health status. Individuals with health issues may still be considered "normal" based on this statistical range. Unfortunately, many doctors and healthcare professionals don't understand the difference between normal and healthy.


Rethinking Recommendations: Considerations for Hypogonadism and Receiving TRT


Hypogonadism is the medical term for having low testosterone. The existing recommendations for diagnosing hypogonadism (low testosterone) and determining eligibility for testosterone replacement therapy (TRT) operate under the assumption that men within the "normal" or statistically calculated range are healthy. According to these guidelines, individuals must have both total testosterone levels of 300 to 350 or lower and symptoms of low testosterone to be diagnosed with hypogonadism. However, it's crucial to recognize that men with higher testosterone levels can still experience symptoms if they fall below their body's sensitivity threshold. Surprisingly, none of the guidelines mentioned below address testing for testosterone sensitivity. Moreover, free testosterone is not mentioned, which is the "usable" form of testosterone and holds a greater significance than total testosterone. Even if your total testosterone levels are very high, having low free testosterone will result in symptoms of low testosterone.


Recommendations from Medical Organizations


Endocrine Society: According to the 2018 update of the Endocrine Society's Clinical Practice Guidelines, a diagnosis of low testosterone (hypogonadism) and consideration for TRT might be made when a patient has low total testosterone levels (less than 300 ng/dL) on more than one occasion, typically in the morning. Symptoms or conditions that might suggest low testosterone, such as low sex drive, erectile dysfunction, or unexplained anemia, should also be present.


American Urological Association (AUA): The 2018 AUA guideline suggests that clinicians should diagnose testosterone deficiency only in men with consistent symptoms and signs and unequivocally low serum testosterone levels. While the exact threshold is not explicitly stated, it's generally aligned with the Endocrine Society's recommendation of less than 300 ng/dL.


European Association of Urology (EAU): The EAU recommends a similar approach as the above, suggesting that late-onset hypogonadism (which would qualify for TRT) is a clinical and biochemical syndrome that might benefit from testosterone treatment if serum testosterone is repeatedly below 12 nmol/L (approximately 350 ng/dL) and if there are significant symptoms of testosterone deficiency.


International Society for Sexual Medicine (ISSM): The ISSM's 2015 recommendations suggest that testosterone deficiency might be diagnosed with consistent symptoms and signs and a serum total testosterone level of less than 12 nmol/L (approximately 350 ng/dL).


While these guidelines provide a framework for diagnosing low testosterone and considering TRT, it's important to acknowledge the limitations of relying solely on total testosterone levels and definitions of normal, not based on a lack of symptoms. Also, assessing free testosterone and individual variations in testosterone sensitivity can provide a more comprehensive evaluation of an individual's hormone status.


By understanding potential gaps in the current guidelines, individuals can engage in informed discussions with healthcare providers and advocate for a personalized approach that considers their specific symptoms, free testosterone levels, and overall hormone sensitivity.


What Do Doctors Who Specialize in Men’s Health Recommend?


Based on my observations, doctors specializing in men's sexual health often recommend higher testosterone levels for optimal overall health. Additionally, they tend to place more emphasis on free testosterone rather than total testosterone levels. While there are some variations among these doctors, the general recommendations are typically total testosterone levels of 700 to 800 or higher and free testosterone levels of 20 to 25 or higher for optimal health. It's important to note that these recommended levels are suggested for most men, assuming they have normal testosterone sensitivity.


Take Aways and My Recommendations


Takeaways:


  1. Normal does not necessarily equate to healthy. "Normal" is a statistical calculation based on average levels.

  2. Testosterone test numbers are important, but testosterone sensitivity can significantly impact their interpretation.

  3. Treatment decisions should be based on symptoms rather than solely on statistical calculations.

  4. Doctors specializing in men's sexual health generally consider total testosterone levels of 700 or higher indicative of healthy levels.


Recommendations based on test results:


  1. Suppose your testosterone levels are low, but you don't experience symptoms. In that case, I recommend focusing on natural methods to raise testosterone levels, such as maintaining a healthy diet, getting adequate sleep, and engaging in regular exercise. Discuss your test results and lack of symptoms with a doctor knowledgeable about testosterone nuances.

  2. If your testosterone levels fall within the normal ranges, but you experience symptoms, seeking a doctor specializing in men's health is advisable for comprehensive testing. Finding a specialist increases the likelihood of receiving proper care based on symptoms.

  3. If your testosterone levels are below normal, you will likely find doctors to treat you. However, ensure that the doctor you choose is knowledgeable and experienced in men's health and testosterone management.

  4. You are probably fine if your testosterone tests show high levels and you have no symptoms. Nevertheless, it is prudent to continue monitoring your levels regularly.


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