
Testosterone is responsible for the improvement of male sexual characteristics and this hormone formed by the testicles. It is also important to maintain various functions such as sexual function, bone growth, adequate levels of red blood cells, and a sense of well being and muscle bulk. Insufficient production of testosterone causes erectile dysfunction. Erectile dysfunction occurs due to decreased testosterone production to overcome this testosterone replacement therapy is used to improve the problem. Testosterone replacement therapy occurs in various forms containing its own set of advantages and hazards such as subdemal pellets, transdemal patches and injections. Testosterone replacement therapy also helps to recover symptoms of low testosterone. Low testosterone is caused due to age growth it generally lowers down after the mid 30's and further decreases accordingly to the age factor.