How SHBG Affects Testosterone
Many men present with symptoms commonly associated with low testosterone — fatigue, reduced libido, poor recovery, or loss of motivation — yet are told their testosterone levels are “normal”. Others are offered testosterone therapy despite blood results that suggest their body is still capable of producing adequate testosterone.
One of the most common reasons for this confusion is sex hormone-binding globulin (SHBG). Despite its importance, SHBG is frequently misunderstood or not adequately considered when interpreting testosterone results.
What Total Testosterone Actually Represents
Total testosterone reflects the amount of testosterone the testes are producing and releasing into the bloodstream. In other words, it is a marker of production capacity, not effectiveness.
A total testosterone level around 15 nmol/L or higher often indicates that the testes are still functioning reasonably well. In isolation, this level does not automatically justify testosterone replacement therapy (TRT).
What total testosterone does not tell us is how much of that hormone is actually available to tissues such as muscle, brain and sexual organs. This is where SHBG becomes clinically important.
What Is SHBG and Why It Matters
SHBG is a protein produced primarily by the liver. Its role is to bind circulating sex hormones, including testosterone.
Once testosterone is bound to SHBG, it is largely unavailable for biological activity. Higher SHBG levels mean a greater proportion of testosterone is bound, reducing the amount that can act at tissue level.
As a result, a man may have a total testosterone level that appears acceptable, yet experience symptoms consistent with androgen deficiency because hormone availability is reduced.
Why Symptoms and Blood Results Often Do Not Match
Men with elevated SHBG commonly report:
Persistent fatigue
Reduced libido
Poor exercise recovery
Difficulty building or maintaining muscle
Reduced motivation and drive
These symptoms are often attributed to ageing, stress or lifestyle alone. Without understanding SHBG, it is easy to dismiss the hormonal contribution or, conversely, to prescribe TRT without addressing the underlying issue.
High SHBG Should Prompt Investigation, Not Assumption
One of the major shortcomings in men’s hormone care is the failure to ask why SHBG is elevated.
Too many clinics identify high SHBG and move directly to treatment, rather than taking the time to understand what is driving it. In many cases, elevated SHBG reflects a modifiable factor rather than a permanent hormonal deficiency.
Common Causes of Elevated SHBG
Alcohol intake
Regular or excessive alcohol consumption increases SHBG production by the liver. This is a common and often overlooked cause of reduced testosterone availability in Australian men. Reducing alcohol intake can lead to meaningful symptom improvement in some cases.
Thyroid disease
Thyroid hormones influence SHBG production. Men with overactive thyroid function, or subtle thyroid dysfunction, may develop elevated SHBG despite otherwise adequate testosterone production. This is why thyroid assessment is an important part of hormonal evaluation.
Chronic dieting or low energy intake
Prolonged calorie restriction, aggressive fat loss phases, or very low-carbohydrate diets can increase SHBG. This is frequently seen in lean, physically active men who are under-fuelled relative to their training load.
Age
SHBG tends to rise with age. This partially explains why symptoms may appear even when total testosterone remains within the reference range.
Liver health
As SHBG is synthesised in the liver, liver stress — whether from alcohol, medications or metabolic factors — can influence circulating levels.
Genetic variation
Some men naturally produce higher SHBG throughout life. This does not automatically mean TRT is required, but it does mean hormone results must be interpreted carefully and individually.
Why TRT Is Not Always the Right First Step
When total testosterone suggests preserved production capacity and SHBG is elevated, the most appropriate first step is often to identify and address contributing factors.
In many cases, improvements in alcohol intake, nutrition, sleep, stress management or thyroid health can improve hormone availability and symptoms without committing a man to long-term hormone therapy.
TRT may be appropriate when symptoms remain significant, persistent, and unexplained after a thorough medical assessment. However, TRT should support health — not replace proper investigation.
Disclaimer
Information in this article is general in nature and does not constitute medical advice. TRT is a medical treatment that requires proper diagnosis, blood testing and doctor supervision. Always consult an Australian-registered medical practitioner before starting or changing any treatment.