As men age, it a well known fact and unfortunate truth that the male hormone testosterone, responsible for masculine attributes, some male muscle tone, sex drive and virility and a slew of other things that are important to men, declines slowly at first and then more rapidly as men grow older.  This accounts for a number of issues sexually, and often leaves a man feeling, well, old, for lack of a better word! 

Testosterone therapy, much like HGH enhancing supplements or the controversial HGH growth hormone injections, is supposed to make men feel better, more invigorated, more virile, and in short, much like they did when they were young bucks, so to speak. 

The decrease in testosterone in men who age has been likened to a female phenomena, menopause, and is termed by some docs as Andropause, the male equivalent of menopause, where the aging process so ungraciously takes away the very hormones that make us what we are - a man or a woman, respectively. 

New research, however, has suggested that although the testosterone suppelementation may make men feel better, it often can have side effects that are not so cool, such as increase high blood pressure (which can lead to strokes and increases in heart troubles), and kidney function problems. 

The studies so far have focused on control groups of  rats given testosterone, and rats not given testosterone, and reportedly the rats that had the testosterone had higher blood pressure in a statistically significant number, and the rats that did not have the testosterone infusions did not have high blood pressure, and the rats that had the testosterone also exhibited signs of potential kidney functioning problems, with higher levels of protein in their pee, indicating tha the kidneys were not functioning at peak levels.