Masculinity is controlled by the male hormones, which are called androgens. The most important of these is a hormone called testosterone. Nearly all the body's supplies of testosterone are made by the testicles.

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. Sometimes, however, men who develop testicular cancer may have testicles which aren’t working properly and only produce small amounts of testosterone. In this situation removal of one testicle may mean that the one left behind can’t produce enough testosterone and levels may fall sufficiently to cause some problems. Also, very occasionally, there may be cancer in both testicles and both will have to be removed. This will lead to an abnormally low level of testosterone.

If changes in masculinity do develop in the months after an operation for testicular cancer it’s possible to have a blood test to measure the concentration of testosterone in the blood. The concentration of the hormone is measured in nanomoles per litre (which is shortened to 'nmol/L'). The normal range of testosterone levels is from 10nmol/L up to 41nmol/L, in healthy young men.

If the blood test shows a level of testosterone much less than 10nmol/L then symptoms of male hormone deficiency are quite likely (with tiredness, weakness, low mood/ depression and loss of sexual interest and libido). In this situation it’s possible to have hormone replacement therapy (HRT) to increase testosterone levels.

There are different types of HRT. These include injections, tablets and patches or gels that can be applied to the skin.

• Injections into the muscle. This is the most common way of having the treatment. Injections give steady levels of testosterone in the blood for most of that time. Levels may be a bit higher than normal immediately after the injection and a bit lower than normal just before the next injection is due. They’re given at regular intervals and the time between injections varies depending on the type of injection you are given. Types of injections include Testosterone Entanate (every 3–6 weeks), Sustanon 100® (every 2 weeks) Sustanon 250® (every 3 weeks), Nebido® (every 10–14 weeks).

• Patches applied to the skin daily. The testosterone is slowly absorbed over 24 hours and gives steady blood levels of testosterone. The patches have to be placed on a different area of skin each day for 7 days, before returning to the original area, as they can cause skin reactions. Reactions include soreness, irritation and rashes and happen to about 1 in 3 men who use patches. Patches include, Andropatch®.

• Gel put on the skin of the upper arms or shoulder once a day after bathing. It’s important not to shower or wash the skin for 6 hours after applying the gel. To prevent transferring testosterone to other people, skin to skin contact on the areas where the gel has been applied should be avoided. Gels include Testim® and Testogel®.

• Tablets placed between the gum and lip twice a day. These are called buccal tablets. The testosterone is absorbed through the mouth into the bloodstream to give a steady level of the hormone for 12 hours. Striant® is a type of buccal tablet.

• Tablets or capsules taken 2–3 times daily after meals. Because tablets aren’t as reliable at giving steady blood levels of testosterone as other treatments, they’re usually only used if other treatments aren’t suitable. Capsules include Restandol®.

• Implants. Testosterone-based pellets can be implanted under the skin giving a fairly even level of the hormone in the blood for a period of 4 to 5 months. A minor operation is needed to put them in and once they are implanted they can’t be reversed, so implants are not widely used.

Having HRT can help with some of the physical side of masculinity: It can continue the growth of facial and body hair.  It can also keep a 'male' balance between fat and muscle in the body (men who have very low testosterone levels tend to develop more fat and lose some of their muscle tissue). HRT can also help with some of the emotional or psychological side of loss of masculinity in about 3 out of 4 men. So, men who have problems with loss of interest in sex, difficulty with getting erections or feeling low in mood and tired may find that HRT can help.