Why Your Total Testosterone Is Normal But Free T Is Low

A total testosterone result inside the reference range doesn't always tell the full story. When sex hormone-binding globulin (SHBG) runs high, it binds more circulating testosterone and leaves less of the unbound fraction available to act on tissues. Total testosterone may look normal on paper while free testosterone is low, and symptoms sometimes associated with testosterone deficiency may still be present. The Endocrine Society's 2018 clinical practice guideline recommends measuring free testosterone when total testosterone sits near the lower limit of normal or when a condition known to alter SHBG is present (Bhasin et al., 2018). Direct-pay diagnostic lab panels that include total testosterone, free testosterone, and SHBG may provide a more complete picture than a single total testosterone value alone.

That gap between a "normal" total result and a low free result is a pattern that can go unrecognized in routine hormone evaluation. Understanding why it happens, which labs to order, and what the numbers actually mean puts a man in a stronger position to have a productive conversation with a provider.

What Is the Difference Between Total and Free Testosterone?

Total testosterone measures every form of the hormone circulating in the blood, both bound and unbound. About 98% of circulating testosterone is attached to carrier proteins. In most men, approximately 44% is bound tightly to SHBG, roughly 54% is bound loosely to albumin, and the remaining 1-3% circulates unbound. That unbound fraction is free testosterone.

Free testosterone is the portion available to enter cells and activate androgen receptors. Testosterone bound to albumin detaches relatively easily and is sometimes grouped with free testosterone under the label "bioavailable testosterone." Testosterone bound to SHBG, by contrast, is held tightly and is not readily available to tissues.

This distinction matters because two men can have identical total testosterone values and very different free testosterone levels, depending entirely on how much SHBG each one carries.

How Does SHBG Control How Much Free Testosterone Is Available?

SHBG is a glycoprotein made mostly by the liver. Its job is to transport sex hormones through the bloodstream and regulate how much of each hormone remains unbound. When SHBG production rises, more testosterone gets locked into a bound state, and the free fraction falls.

Several conditions are known to raise SHBG levels:

• Aging (SHBG tends to rise gradually after age 40)

• Hyperthyroidism

• Chronic liver disease, including hepatitis and cirrhosis

• Certain medications, including anticonvulsants and estrogen-containing drugs

• HIV

In the opposite direction, conditions that suppress SHBG can make total testosterone appear low while the free fraction remains adequate. These include obesity, type 2 diabetes, insulin resistance, hypothyroidism, and glucocorticoid use (Bhasin et al., 2018). The lab bundles that test testosterone alongside SHBG and albumin capture both sides of this equation.

Why Can Total Testosterone Look Normal While Free T Is Low?

The short answer: elevated SHBG binds more testosterone and shrinks the free fraction, even though the total amount in the blood hasn't changed.

Consider a man in his late 50s whose total testosterone falls well within the harmonized reference range for healthy men (Travison et al., 2017). If his SHBG is elevated above the typical male reference ceiling, a large share of that total testosterone is protein-bound and unavailable. His calculated free testosterone may fall below the level where symptoms sometimes associated with deficiency, such as reduced libido, fatigue, or changes in body composition, may warrant further evaluation. A provider looking only at total testosterone would see a normal result. The clinical picture may tell a different story.

The Endocrine Society guideline addresses this directly. Free testosterone measurement (by equilibrium dialysis or a validated calculation using total testosterone, SHBG, and albumin) is recommended when total testosterone is near the lower limit of normal, or when an SHBG-altering condition is present (Bhasin et al., 2018). A 2024 review in the Cleveland Clinic Journal of Medicine reinforced this approach, noting that in men with obesity who have low total testosterone, measuring free testosterone to confirm the diagnosis may be useful (Shumaker et al., 2024).

Which Free Testosterone Test Is Accurate?

Not all free testosterone assays produce reliable results. Direct analog immunoassays, the most commonly available method at commercial laboratories, are inaccurate at low concentrations and should not be used to make clinical decisions. The Endocrine Society's 2018 guideline states this explicitly and recommends either equilibrium dialysis or a validated calculation from total testosterone, SHBG, and albumin (Bhasin et al., 2018).

Equilibrium dialysis is considered the reference standard, but it's expensive and not widely available outside reference labs. The calculated free testosterone, using the Vermeulen equation with CDC Hormone Standardization Program (HoST)-certified total testosterone measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), is the practical alternative most guidelines endorse.

When ordering labs, confirming which methodology a laboratory uses for free testosterone is worth the 2-minute phone call. A testosterone panel that specifies LC-MS/MS for total testosterone and a calculated free testosterone from SHBG and albumin gives a more dependable result than a cheap direct immunoassay.

How Is Low Free Testosterone Diagnosed?

Evaluation of testosterone deficiency follows a specific protocol, whether the concern is low total, low free, or both. The AUA guideline identifies a clinical threshold for total testosterone that, combined with symptoms, may support further evaluation. That level should be measured on at least two separate fasting early-morning draws per guideline protocol (Mulhall et al., 2018). About 30% of men with an initially low value have a normal result on retest due to diurnal variation and day-to-day fluctuation (Bhasin et al., 2018). That statistic alone is why the two-draw requirement exists.

When total testosterone is confirmed low, LH measurement can help a provider determine the underlying cause of low testosterone. If total testosterone is borderline or SHBG is elevated, free testosterone becomes an important part of the evaluation.

Symptoms matter as much as numbers. Guidelines emphasize that a lab value alone is not sufficient for a diagnosis. Symptoms that may warrant evaluation, including reduced libido, erectile dysfunction, fatigue, loss of muscle mass, and depressed mood, combined with confirmed low levels, are both required (Mulhall et al., 2018). Men who have concerning symptoms and want a clear picture can start by ordering hormone testing that covers total testosterone, free testosterone, SHBG, estradiol, and LH on a single draw.

What Should You Know Before Considering Treatment?

If lab work confirms low free testosterone alongside symptoms, treatment may be appropriate. Testosterone replacement therapy (TRT) is FDA-approved for men with hypogonadism from a diagnosed medical condition. It is not approved for age-related decline alone, a distinction the FDA's Limitation of Use language retained in the February 2025 labeling update (FDA, 2025).

That same 2025 update added the results of the TRAVERSE trial to all testosterone product labels. TRAVERSE enrolled 5,246 men aged 45-80 with hypogonadism and preexisting or high cardiovascular risk. The primary cardiac endpoint (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke) was neutral at 7.0% in the testosterone group versus 7.3% in the placebo group (Lincoff et al., 2023). The trial also found higher rates of atrial fibrillation (3.5% vs 2.4%), acute kidney injury (2.3% vs 1.5%), and pulmonary embolism (0.9% vs 0.5%) in the testosterone group. The FDA removed the prior cardiovascular boxed warning but added a new blood-pressure warning based on ambulatory monitoring data.

Treatment involves ongoing monitoring. Guidelines recommend tracking hematocrit during therapy, with specific thresholds that may prompt a provider to adjust the dose or consider phlebotomy (Mulhall et al., 2018). Estradiol, blood pressure, and PSA (in age-appropriate men) are also tracked at regular intervals. Exogenous testosterone suppresses spermatogenesis, and the degree of suppression and recovery varies between individuals. Men who may want to preserve fertility should discuss that with their provider before starting any protocol. A pre-therapy panel that captures baseline markers alongside testosterone gives a provider data that can support a more informed starting point.

All treatment decisions are made between a client and a licensed provider, based on lab confirmation, clinical evaluation, and individual risk factors.

How to Read Your Results and Decide on Next Steps

A single total testosterone value, by itself, can be misleading. The pattern this article describes, normal total testosterone with low free testosterone due to elevated SHBG, is common in men over 40 and in men with thyroid disease, liver conditions, or specific medication use. It doesn't always require treatment, but it does require accurate testing.

A provider may consider ordering total testosterone (by LC-MS/MS), calculated free testosterone, SHBG, albumin, and LH as part of a thorough evaluation. Any low value should be confirmed with a repeat fasting morning draw. From there, reviewing the results with a provider who can weigh the numbers against the symptoms is the step that turns data into a plan. Clients looking for lab testing options can review how the process works before placing an order.

Disclaimer: This blog post is intended for informational purposes only and should not be considered medical advice. Always consult a healthcare professional before making changes to your health routine.

FAQs

Can total testosterone be normal while free testosterone is low?

Yes. When SHBG is elevated, it binds a larger share of circulating testosterone and leaves less in the unbound, active form. The Endocrine Society's 2018 guideline recommends checking free testosterone (by equilibrium dialysis or a validated calculation) whenever total testosterone is near the lower limit of normal or when an SHBG-altering condition is present.

What causes high SHBG in men?

SHBG rises with aging, hyperthyroidism, chronic liver disease (hepatitis, cirrhosis), HIV, and certain medications including anticonvulsants and estrogen-containing drugs. SHBG tends to climb gradually after age 40, which is one reason free testosterone falls faster than total testosterone in older men.

Is a direct free testosterone test accurate?

Direct analog immunoassays for free testosterone are widely available but inaccurate, particularly at low concentrations. The Endocrine Society's 2018 guideline warns against using them for clinical decisions and recommends equilibrium dialysis or a validated calculation from total testosterone, SHBG, and albumin instead.

How many blood draws are needed to confirm low testosterone?

Guidelines from both the AUA and the Endocrine Society require at least two fasting early-morning blood draws on separate occasions. About 30% of men with an initially low value have a normal result on retest, which is why a single draw is not sufficient for evaluation.

Does the TRAVERSE trial prove testosterone therapy is safe?

Not entirely. The primary cardiac endpoint (cardiovascular death, nonfatal myocardial infarction, nonfatal stroke) was neutral at 7.0% vs 7.3% over a mean follow-up of about 33 months. The trial also found higher rates of atrial fibrillation, acute kidney injury, and pulmonary embolism in the testosterone group. The FDA removed the prior boxed cardiovascular warning in February 2025 but added a new blood-pressure warning.

What labs should be ordered when total testosterone is normal but free T is low?

A thorough evaluation may include total testosterone by LC-MS/MS, calculated free testosterone (from total testosterone, SHBG, and albumin), LH, estradiol, and hematocrit. This combination can help distinguish between low total, low free with high SHBG, and pituitary-level issues, and it gives a provider baseline markers that may support clinical decision-making.

Can lifestyle changes raise free testosterone?

Lowering SHBG through body composition improvement, better insulin sensitivity, and reducing alcohol intake may increase the free fraction. Resistance training and adequate sleep support total testosterone production, which also raises the free portion. These interventions don't replace medical evaluation when symptoms are present, but they address modifiable factors that influence the total-to-free ratio.

References

• Cleve Clin J Med. 2024;91(2):93-95.

• J Clin Endocrinol Metab. 2017;102(4):1161-1173.

• J Clin Endocrinol Metab. 2018;103(5):1715-1744.

• J Urol. 2018;200(2):423-432.

• N Engl J Med. 2023;389(2):107-117.

• US FDA. Class-wide labeling changes for testosterone products. 2025.