The testicles produce most of the body's supply of male hormones. These hormones are called androgens and the most important of the androgens is a hormone called testosterone.

Usually removing just one testicle will have little or no effect on the production of testosterone, with the remaining testicle being able to keep up a normal level of the hormone. Sometimes, however, men who develop testicular cancers may have testicles which are not working properly and only producing fairly small amounts of male hormone. In this situation removal of one testicle may mean that the one that is left behind cannot produce enough testosterone and the levels may fall sufficiently to cause some problems. Also, very occasionally, there may be cancers in both testicles and both will have to be removed which will lead to a fall in testosterone to an abnormally low level.

If a man does develop very low testosterone levels in the months after surgery for testicular cancer then it is possible to have hormone replacement therapy (HRT) but this is not often needed and the great majority of men who have a testicle removed for a cancer will not have problems with hormone deficiency and will not have to have HRT.