Testosterone is a hormone produced by the testicles and is responsible for the proper development of male sexual characteristics. Testosterone is also important for maintaining muscle bulk, adequate levels of red blood cells, bone growth, a sense of well-being, and sexual function.
The only accurate way to detect the condition is to have your doctor measure the amount of testosterone in your blood. Because testosterone levels fluctuate throughout the day, several measurements will need to be taken to detect a deficiency. Doctors prefer, if possible, to test levels early in the morning since this is when testosterone levels are at their highest.