Are you one of the millions of men that complain of fatigue, weight gain and low sex drive? The cause could be low levels of testosterone.

According to Urologist Dr. Seth Capello, testosterone is the male hormone, which is produced by the testicles and men over the age of thirty, it begins to decline. It's called andropause, but in some men, their levels drop more than others do. It's a natural part of aging but can also be caused by chronic diseases.

"Kidney disease, heart disease, high blood pressure and diabetes," said Capello.

While it's uncommon, some men have symptoms.

"Fatigue, mood changes, depression, decrease in sexual function, desire for intercourse," said Capello.

A blood test can determine if a man's hormone level is low. Testosterone can be replaced with injections every two weeks or a gel can be rubbed on to the skin each day.

"There are some side effects, contact dermatitis, inflammation of the skin, irritation, transference from man to women or to children which we worry about a lot," said Capello.

In the past two years, a more affordable option is available. This tiny pellet, which is placed under the skin.

"In the office it is with local anesthesia, it slowly releases testosterone to the body over in a three to six month period. So it's actually very well tolerated," said Capello.

While treatment options have proven to be very effective there are side effects you need to be aware of.

Too much testosterone can cause enlarged prostate and behavioral issues like increased aggression.

"With increased testosterone levels men with enlarged prostate might notice worsening of the urinary symptoms low stream getting up at night and if a man has prostate cancer and we haven't found, it can accelerate a prostate cancer that is there. So, it is very important that men just don't go on testosterone without having consulted with their physicians first," said Capello.