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Doctor's Assessment Included

Every result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.

Hormones

Free Testosterone

Free testosterone is the biologically active form of testosterone that is not bound to proteins. In older adults, free testosterone levels tend to decline gradually, and monitoring may help provide context for changes in energy, mood, or muscle strength.

Reference Ranges

Male
pmol/L
Low 170 Normal 700 High
Female
pmol/L
Low 3 Normal 29 High

Reference ranges may vary between laboratories. When you order a test, a BIG-registered doctor assesses your personal results in context. For treatment decisions, discuss your results with your GP.

What It Measures

This test measures the fraction of testosterone not bound to proteins like SHBG or albumin. Free testosterone represents roughly 1-3% of total testosterone but is the most biologically active form. Your healthcare provider may compare this with total testosterone for a complete picture.

Why It Matters

Free testosterone drives muscle development, energy levels, mood, and sexual function. Even when total testosterone appears normal, low free testosterone could suggest functional deficiency. Discussing your results with a healthcare provider may help identify whether further evaluation is warranted.

When to Test

Your healthcare provider may recommend testing free testosterone when experiencing fatigue, reduced libido, muscle loss, or mood changes. It could also be useful when total testosterone is normal but symptoms persist. Consult your provider for advice on optimal testing timing.

Symptoms

Low Levels

Some people may experience persistent fatigue, decreased muscle mass, low mood, reduced libido, or difficulty concentrating when free testosterone is low. Weight gain and decreased bone density could also suggest insufficient bioavailable testosterone. A healthcare provider can help assess your symptoms.

High Levels

Elevated free testosterone may be associated with acne, excess hair growth, irritability, or aggression. In women, high levels could suggest polycystic ovary syndrome or other hormonal conditions. Your healthcare provider can evaluate whether your levels require further investigation.

Recommendations

Male

If Low

Low free testosterone may cause symptoms despite normal total testosterone. Consider SHBG testing and consultation with an endocrinologist.

If High

Elevated free testosterone may indicate steroid use or testicular tumors. Consult with an endocrinologist for comprehensive evaluation.

Female

If Low

Low free testosterone may cause decreased libido and energy. Consider comprehensive hormone evaluation with an endocrinologist.

If High

High free testosterone may indicate PCOS or adrenal disorders. Consider evaluation for PCOS and lifestyle modifications including weight management.

Lifestyle Tips

Regular resistance training, adequate sleep, stress management, and maintaining a healthy body weight may support healthy testosterone levels. Ensuring sufficient zinc and vitamin D intake could also contribute positively. Always discuss supplementation or significant lifestyle changes with your healthcare provider.

Frequently Asked Questions

What is free testosterone?
Free testosterone is the unbound, active form that can directly enter cells and drive biological effects.
How does it differ from total testosterone?
Total testosterone includes bound and unbound forms; free testosterone measures only the active, usable fraction.
Can exercise affect free testosterone?
Resistance training and healthy sleep patterns may support free testosterone. Consult your provider for guidance.

Test Products

This marker is included in the following test panels.