top of page

Low Testosterone Levels: Free vs. Total Testosterone

If you're a man over 40, then you know that your testosterone levels are slowly declining every year. You may not feel it yet, but it's happening. Your libido isn't what it used to be and you're starting to put on a few extra pounds around the waist. It's hard to stay motivated at work and in the gym. You feel like you're losing your edge.

It's critical to understand that low total and free testosterone can contribute to your symptoms and overall health. This article will look at the differences between free and total testosterone.

It's critical to understand that both low total testosterone and low free testosterone can contribute to your symptoms and overall health. In this article, we'll look at the differences between free and total testosterone.

What is Low Testosterone?

Most men are familiar with the concept of testosterone, even if they don't know exactly how it works. Testosterone is the primary male sex hormone and an anabolic steroid. The prominent role of testosterone is to maintain male reproductive tissue, including the testes and prostate, as well as stimulate secondary sexual characteristics such as increased muscle mass and bone density.

Testosterone levels decline with age, beginning at around age 40. Low testosterone, or hypogonadism, can cause a variety of symptoms, including:

  • Fatigue

  • Reduced libido

  • Erectile dysfunction

  • Decreased muscle mass

  • Mood changes

  • Unexpected weight gain

As you can see, the symptoms of low testosterone can have a significant impact on your life. Furthermore, low T levels can put you at risk for a variety of other health problems, including obesity, osteoporosis, metabolic syndrome, and diabetes.

Many people are unaware that doctors can test for two types of testosterone levels: total testosterone and free testosterone. If either is low, you may develop symptoms and health complications.

Total Testosterone

Total testosterone is the amount of testosterone in your blood. It’s made up of two types: unbound (free) testosterone and bound testosterone. Bound testosterone is attached to proteins like sex hormone binding globulin (SHBG) and albumin. Unbound testosterone is not bound to any proteins and circulates freely in the blood.

Total testosterone is important to look at if you have low testosterone symptoms because it provides a comprehensive picture of overall testosterone production. If you have low levels of total testosterone, your body may not have enough to perform important functions such as red blood cell production, sex drive regulation, and muscle mass growth.

Free Testosterone

Free testosterone is the portion of circulating testosterone that is not bound to proteins in the blood, including sex hormone-binding globulin (SHBG). SHBG binds to testosterone, making it unavailable for use by the body. Typically, the amount of free testosterone in your body ranges between 2% and 5% of total testosterone. Low free testosterone levels can also cause testosterone deficiency symptoms.

You Can Have Low Free Testosterone Levels While Having Normal Total Testosterone Levels.

As you might expected, if you have low total testosterone levels, you tend to have low free testosterone levels as well.

However, you can also have low free testosterone while having normal total testosterone levels in your blood. This is usually caused by high levels of SHBG in your blood. Total testosterone production declines as we age, while SHBG rises.

This can put you at risk for low-free testosterone symptoms, even if your total testosterone is at the normal level.

Low Testosterone: How Do Doctors Diagnose It?

There are a few different ways that doctors can diagnose someone's testosterone levels. The most common method is to do a blood test. This is usually done in the morning because testosterone levels are typically highest then.

A physical examination may also be performed to look for signs of low testosterone, such as small testicles or thinning hair. They may also use the Androgen Deficiency in the Aging Male (ADAM) questionnaire to inquire about symptoms such as low sex drive or difficulty getting erections.

Low Testosterone: How Do Doctors Diagnose It?

Blood Tests: Total Testosterone vs. Free Testosterone

When it comes to testosterone blood tests. It is important to test for both total testosterone and free testosterone levels.

So why does this matter? As we mentioned in an earlier section, you can have normal total testosterone and low free testosterone due to high SHBG levels. It's the free testosterone that's available to bind to receptors and exert its effects on things like muscle mass and strength, sex drive, etc. That's not to say that total testosterone levels don't matter - they do!

Treating Low Testosterone Levels

One key factor in managing low testosterone is maintaining a healthy lifestyle. This means eating a balanced diet, exercising regularly, and getting enough sleep. Additionally, avoiding tobacco and excessive alcohol use can also help improve testosterone levels.

Testosterone replacement therapy (TRT) can help improve these symptoms and restore quality of life. TRT involves delivering testosterone into the body through injections, patches, gels, or implants. While TRT is generally safe and effective, it's not right for everyone. Talk to your doctor about whether TRT is right for you. One side effect of long-period usage (>6 months) of Testosterone Replacement Therapy (TRT) is testicular atrophy, also referred to as testicular shrinkage.


It is important to understand the difference between free and total testosterone levels in order to ensure proper health. Total testosterone levels can be affected by a number of factors, including age, weight, and health conditions. However, normal total testosterone doesn't mean one will have a normal "free" testosterone level. Speak with a doctor if there are concerns about either form of testosterone.

Related read:


Sign up for our mailing list and stay up-to-date on the latest health news, tips and advice!

Thanks for subscribing!

Featured Posts

bottom of page