You see it on TV all the time. “Feeling depressed? It might be low testosterone.” “Not feeling like yourself? It might be low testosterone.”

And then there’s the biggie. “Not feeling as interested in sex as you used to be?” You got it. It might be low testosterone. So, is low T, as it is commonly referred to, really such a big deal when it comes to low libido?

According to Harvard urologist Dr. Abraham Morgentaler, founder of Men's Health Boston and the author of Testosterone for Life, it is.

“Low T can cause symptoms of reduced sexual interest or performance, difficulty achieving an orgasm and reduced genital sensitivity,” he said.

Clearly, not good. And that’s just the beginning. Low T can also cause “lack of energy, reduced sense of vitality, chronic fatigue, reduced stamina or muscular performance, depressed or flattened mood, irritability and increased abdominal fat.

And all of those things, of course, can put a damper on libido in and of themselves. Not to mention that low T is also associated with shorter life span, increased risk of obesity, developing diabetes or the metabolic syndrome (an indicator of cardiovascular risk) and osteoporosis.

And if you’re worried about or suffering from the above, that can definitely do a number on your sex life too.

In other words, when it comes to one’s sex life, low T can be a very big deal. The good news is, all one needs is a simple blood test to find out if you have low T. So, when is testing recommended? Well, Morgentaler said, if one has “symptoms of decreased libido, erectile dysfunction, chronic fatigue, reduced exercise capability/stamina and depressed mood (the ‘blahs’),” testing would be a good idea.

Morgentaler believes it’s important to measure total T, which is the traditionally accepted method, as well as free T, which is considered more accurate since it’s the bioavailable portion of T within the bloodstream.

“Some men will have normal-appearing levels of total T, but low free T, and those men benefit from treatment,” he said.

Once the test comes back, the doctor can check the levels and consider those in reference to the symptoms if any.

So many problems with sex involve trial and error, counseling and arduous testing. Although low T might be a tough diagnosis at first mentally, it’s really no big deal and a very easy fix. Having low T does not make one less of a man. But not getting help for it is not a very manly move.

If the test shows that low T is an issue, it can be treated with, of course, testosterone.

“The most popular forms of treatment are gels, injections, and pellets placed under the skin,” Morgentaler said. “The advantage of the pellets is that they are the only long-acting form of treatment, providing good T levels for three to four months at a time, whereas gels must be applied daily, and injections are performed at one to two week intervals.”

As with most medications, there can be side effects, including acne, breast tenderness or enlargement, swelling of feet and/or ankles, and an increase in the number of red blood cells.

The good news is that none of these are common and all of them can be resolved with the termination of treatment, Morgentaler said. And it is not, as previously thought, a risk for prostate cancer.

When it comes to sex, low T can be a problem for women too. So, post-menopausal women and women with low libido or vitality might want to have their testosterone levels checked as well.

“Testosterone does seem to help a significant proportion of these women,” he added. “However, T treatment in women is relatively new and not yet approved by the FDA for this use.”

The bottom line is this: It’s a simple blood test that can significantly change one’s quality of life.

“It is not a ‘cure’ for everyone, but there is no doubt that a great many men who are treated for low T feel like they are ‘alive again,’ with increased energy, sexual desire, and a renewed sense of purpose and vitality,” Morgentaler said.

The same goes for women.

If you just don’t feel raring and ready to go like you used to, get tested. You just might be surprised at how quickly you’ll be back to your old self again.

Jenny Block is a freelance writer based in Dallas, Texas. She is the author of "Open: Love, Sex, and Life in an Open Marriage." Her work also appears in "One Big Happy Family" edited by Rebecca Walker and "It’s a Girl: Women Writers on Raising Daughters" edited by Andrea Buchanan. Visit her Web site at www.jennyonthepage.com.