Does men's testosterone increase with age? It is generally thought that men's testosterone **decreases** with age. However, according to Des Tobin, Professor of Cell Biology at the University of Bradford: > Surprisingly the levels of testosterone [in men] continue to increase with age up until the age of 70. This is corroborated here: > For men, again the change in eyebrows is due to hormonal changes. For many their levels of testosterone remain at a good level or even continue to increase up to the age of around 70 and this can encourage vigorous hair growth particularly in areas that were perhaps not as robust in younger years – areas such as the nose, ears and eyebrows. Given that both extracts mention the age of 70, are they perhaps referring to a single study? Is Professor Tobin wrong?

One study argues the opposite, that testosterone drops with age:

> In the present study in 890 generally healthy, middle class, American men in the BLSA, we found that both T and free T index (a calculated value related to free or bioavailable T) decreased progressively at a rate that did not vary significantly with age, from the third to the ninth decades.

![Bottom Left: Free T Index vs. Age](

To clarify their wording:

> at a rate that did not vary significantly with age

they are saying that the rate of decrease is constant, that is T decreases linearly with age rather than exponentially or etc.

Source: "Longitudinal Effects of Aging on Serum Total and Free Testosterone Levels in Healthy Men", _Endocrine Society - The Journal of Clinical Endocrinology & Metabolism_