The most important indicator of thyroid health
Thyroid-stimulating hormone (TSH) is a hormone produced by the pituitary gland and plays a central role in regulating the thyroid gland. It signals to the thyroid whether more or less thyroid hormones (T3 and T4) should be produced and is therefore a key indicator of your thyroid function.
A TSH level that is too high or too low can indicate an underactive thyroid (hypothyroidism) or an overactive thyroid (hyperthyroidism) , both of which can significantly affect metabolism, energy levels, hormone balance and psychological well-being.
Why is TSH so important for men's health?
Although thyroid disorders are more common in women, the importance of thyroid levels in men is often underestimated . Especially in cases of chronic fatigue, weight gain despite exercise, loss of libido, or concentration problems, it is worthwhile to examine the thyroid axis.
An imbalanced TSH level can also indirectly affect testosterone levels , as it slows down metabolism and disrupts the body's own regulatory processes.
What values are normal?
Reference values for TSH are usually between 0.3 and 4.0 mIU/L , with values around 1.0 and 2.5 mIU/L often considered "optimal". Values outside the normal range can indicate the following:
- Elevated TSH (> 4.0 mIU/l): Suspected underactive thyroid (hypothyroidism)
- Low TSH (< 0.3 mIU/l): Indication of overactive thyroid (hyperthyroidism)
Important: A single TSH value is often not sufficient; the free hormones fT3 (free triiodothyronine) and fT4 (free thyroxine) should also be measured to obtain a complete picture.
Symptoms of a TSH disorder
An altered TSH level can manifest itself in many ways, often nonspecifically:
In cases of excessively high TSH levels (hypothyroidism):
- Lack of motivation, chronic fatigue
- Weight gain despite unchanged diet
- Loss of libido, potency problems
- sensitivity to cold
- Concentration problems (“brain fog”)
- Depressive moods
In cases of low TSH (hyperthyroidism):
- Nervousness, irritability
- Unintentional weight loss
- Sleep problems, sweating
- Heart palpitations, trembling
- Restlessness despite exhaustion
These symptoms can easily be confused with other hormonal or psychological causes, therefore accurate laboratory diagnostics are crucial .
How is TSH regulated in the body?
The thyroid axis is a finely tuned system consisting of:
- Hypothalamus - releases TRH
- Pituitary gland - produces TSH
- Thyroid gland - reacts with T3 and T4
This feedback system is very sensitive: If the thyroid gland produces too few hormones, TSH levels rise as a "signal" to produce more. Conversely, if there is too much hormone, TSH production is inhibited.
TSH & Testosterone: Is there a connection?
Yes, and it's more significant than many people realize. An improperly regulated thyroid function can:
- The production and availability of free testosterone are affected
- Increased sex hormone-binding globulin (SHBG) → less available testosterone
- This produces symptoms that are mistakenly interpreted as "pure testosterone deficiency".
Therefore, it is important to consider the thyroid gland in every hormonal issue .
How can TSH be influenced?
In some cases, lifestyle changes are sufficient, while in others medication is necessary. Factors that can have a positive effect include:
- Adequate iodine and selenium intake
- Regular sleep & stress reduction
- Avoid excessive dieting or fasting.
- Good gut health (microbiome influences the conversion of T4 to T3)
→ Also read our article on intermittent fasting or iodine in the glossary for further information on its effects on hormone metabolism.
Conclusion
TSH is an indispensable laboratory parameter in modern diagnostics, even when the focus isn't "just on the thyroid." This is because an imbalanced TSH level can affect many other hormonal systems, including testosterone.
Anyone suffering from chronic fatigue, loss of libido, low mood or weight gain should have not only testosterone, but also TSH, fT3 and fT4 levels measured, ideally using the premium testosterone test from Adon Health .
This way you can find out whether you actually suffer from a testosterone deficiency, or whether your thyroid gland is (partly) responsible.
