Why might testicles shrink with age or due to hormonal treatments like TRT?

As men get older, testicles sometimes become smaller because the natural production of testosterone slows down. This is a normal part of aging, like how some parts of our body change over time. When a man uses testosterone replacement therapy (TRT), the body notices the extra testosterone from outside. Because of this, the brain sends fewer signals to the testicles to make their own testosterone. When the testicles are not working as much, they can shrink in size. This is called testicular atrophy. It happens because the signals that normally tell the testicles to produce testosterone are reduced, so they do less work. With aging, the cells in the testicles naturally become less active, and with TRT, the added hormones make the body think it doesn't need as much natural production. Both aging and hormonal treatments can lead to testicular shrinkage in different ways. If you're experiencing concerning symptoms or want to better understand what might be causing changes in your body, try Ubie's free AI-powered symptom checker to get personalized insights before speaking with your doctor about whether any changes in treatment are needed.