The Key Differences Between Free and Total Testosterone

You’re not feeling like yourself, you’re exhausted all the time and can’t seem to concentrate on your work, and your sexual performance is on a decline. Testosterone deficiency — medically known as male hypogonadism — is becoming more prevalent, so checking your testosterone levels might be a good idea. Some of the most significant lab values your provider will assess are your free and total testosterone.

Testosterone deficiency is more likely to occur as you grow older, with levels decreasing consistently starting in your early forties. This is normal, albeit symptoms can be frustrating. However, testosterone deficiency is also spiking in younger males now, changing the significance of low testosterone and its role within society.

Some of the most common triggers leading to the development of low testosterone include sleep deprivation, diabetes, being overweight or obese, and chronic stress — all of which are on the rise too.

If you’re feeling off, a blood test can shed light on what’s going on.

So which lab values are critical in evaluating your testosterone health and how do free and total testosterone fit into the equation?

You’re Experiencing Symptoms: What’s Next?

If you think you may be suffering from testosterone deficiency or don’t know exactly what’s going on but are experiencing symptoms aligned with low testosterone, it’s time to reach out to your doctor to schedule an appointment. This consultation will include an array of assessments including a blood test to determine your free and total testosterone levels.

Your healthcare provider will perform a physical examination and investigate any obvious signs of low testosterone. He will also ask you questions to determine what kind of symptoms you’re experiencing — with declining sexual function generally being one of the first signs of hypogonadism.

Symptoms can differ but can constitute the following:

  • Erectile function
  • Fatigue
  • Poor sexual performance
  • Low libido
  • Memory changes
  • Difficulty concentrating
  • Depressive symptoms
  • Mood changes and irritability
  • Loss of muscle mass
  • Declining hair growth

Your clinician will also order some lab work, focusing on evaluating your free and total testosterone levels — albeit other variables can further play an important role for patients with hypogonadism.

If you’re experiencing symptoms and have been found to have low T levels, your physician will very likely recommend one or the other form of treatment. Treatment can include testosterone replacement therapy (TRT), which can replace serum testosterone with external testosterone.

But first — what levels of free and total testosterone are critical for your health and what’s the difference between the two?

Free vs. Total Testosterone

There are various types of testosterone in your bloodstream and your provider will likely check your total testosterone first or he may assess your free and total testosterone at the same time. 

While both are important and play unique roles in your body, there are differences between free and total testosterone. 

Free testosterone, also dubbed active testosterone, is the portion of your testosterone that is available freely in your body. What does that mean? It means that it's available to be used for functions within your body. Free also means that, unlike other types of testosterone, free testosterone is not bound to protein and can therefore be used when needed.

Other types of testosterone are not considered free as they attach primarily to two prominent proteins; albumin and sex hormone-binding globulin (SHBG). 

Albumin-bound testosterone is considered to be part of the umbrella term bioavailable testosterone despite its attachment to a protein. Albumin-bound testosterone is linked only weakly to the albumin proteins — with connections easily dissolved, which makes it available for use.

SHBG-bound testosterone, on the other hand, makes up roughly 70% of serum testosterone, with SHBG being the most profound testosterone-carrier protein.

On the contrary, total testosterone is the term used to describe all testosterone in your bloodstream; this means all free and protein-bound testosterone. The main difference between free and total testosterone is that free testosterone is defined only as a specific type of testosterone and total testosterone is used collectively for all types combined.

Normal total testosterone can vary from 300 to 750 nanograms per deciliter [ng/dL] while free testosterone normally ranges from 6.6 to 26.5 picograms per milliliter [pg/mL]. These distinct ranges are yet another difference between free and total testosterone as free testosterone only accounts for about 2% of serum testosterone.

How to Raise Free and Total Testosterone?

Levels of the male hormone can be affected by an array of lifestyle factors, including the consumption of alcohol and unhealthy dietary patterns. To raise free testosterone in your bloodstream, you have to follow strategies that reduce the presence of SHBG protein.

Lower amounts of SHBG mean that testosterone is less likely to bind to the protein and remain free. Since SHBG-bound testosterone makes up the majority of serum testosterone, reducing SHBG will leave more testosterone actively available.

Treating conditions like liver cirrhosis and hyperthyroidism that may increase SHBG levels may help. Following a healthy diet and keeping your weight in check can further support the level of SHBG in your blood.

Your Lab Results & What to Do With Them

Your doctor might recommend checking several other lab variables including your luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, and growth hormone (GH) — all of which can impact your testosterone production in one way or another.

LH has an array of roles but is primarily responsible for producing testosterone within the testes. Prolactin can impact LH and hence reduce testosterone synthesis. FSH, in turn, is associated with testicular growth and the production of sperm, while GH can stimulate the production of testosterone. 

Understanding key differences between free and total testosterone, as well as other relevant variables helps you take charge of your health. If your total testosterone is < 300 nanograms per deciliter [ng/dL] and you’re experiencing low T symptoms, it’s time to have a chat with your doctor about what kind of treatment may be available for you.

Are there more variables on your lab report that you don’t fully understand? Fret not! Stay in touch and let’s learn together about testosterone deficiency. 

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