What’s the Difference Between Free and Total Testosterone?

When it comes to understanding hormone health—especially testosterone—two terms often come up: free testosterone and total testosterone. While they sound similar, these two measurements tell us different things about how testosterone functions in your body. Knowing the difference between free and total testosterone can help you and your healthcare provider better assess your overall hormone balance and determine if treatment is needed.

What Is Total Testosterone?

Total testosterone refers to the overall amount of testosterone present in your blood. This includes:

• Free testosterone (unbound and biologically active)
• Testosterone bound to albumin (a protein in your blood; loosely bound and still considered available for use)
• Testosterone bound to sex hormone-binding globulin (SHBG) (tightly bound and not readily usable by the body)

So, when your doctor orders a “total testosterone” test, they’re looking at the complete picture of circulating testosterone, regardless of whether it’s usable or not.

What Is Free Testosterone?

Free testosterone makes up only about 1-3% of your total testosterone—but it plays a big role. This form is not bound to proteins and is biologically active, meaning it can enter cells and trigger the physiological effects associated with testosterone, such as:

• Supporting muscle mass and strength
• Regulating mood and energy
• Influencing sex drive and performance
• Supporting bone density
• Aiding red blood cell production

Even if your total testosterone is in a "normal" range, low free testosterone can still cause symptoms of testosterone deficiency.

Why Does the Difference Matter?

Some patients have normal total testosterone levels, but their free testosterone is low, especially if they have high levels of SHBG (sex hormone-binding globulin). SHBG levels can increase with age, certain medications, liver conditions, and even some lifestyle factors. When SHBG is elevated, more testosterone gets “locked up” and becomes unavailable for your body to use.

This is why measuring both total and free testosterone is essential when diagnosing low testosterone or other hormonal imbalances. Understanding both helps ensure that a treatment plan addresses not just how much testosterone is present, but how much your body can actually use.

Testing Free vs. Total Testosterone

Doctors typically start with a total testosterone test. If levels are borderline or if symptoms persist despite a normal total result, they may follow up with a free testosterone test or measure bioavailable testosterone, which includes both free and loosely bound forms.

Blood samples are typically collected in the morning, when testosterone levels are at their peak. It’s also worth noting that testosterone levels naturally fluctuate throughout the day, so a single test might not give the full picture.

Symptoms of Low Free or Total Testosterone

For both men and women, testosterone imbalances can cause:

• Fatigue or low energy
• Low sex drive
• Mood swings or depression
• Loss of muscle mass
• Difficulty concentrating
• Weight gain
• Poor sleep quality

Whether your issue lies in free or total testosterone, identifying the root cause is key to restoring balance and improving how you feel.

The Bottom Line

Understanding the difference between free and total testosterone is crucial for accurately diagnosing and treating hormone imbalances. While total testosterone gives a broad overview, free testosterone shows what your body can actively use. Both measurements play a role in evaluating your health.

At AlphaMD, we take a comprehensive approach to hormone testing and therapy. Our online platform makes it easy to consult with licensed providers, get your levels checked, and receive personalized treatment—all from the comfort of your home. Whether you're dealing with low energy, mood changes, or other symptoms of hormone imbalance, we’re here to help guide you toward a better quality of life.