It's natural for men to notice a gradual decrease in sex drive (libido) as they age. The degree of this decline varies. But most men maintain at least some amount of sexual interest into their 60s and 70s.

But sometimes loss of sex drive is related to an underlying condition. Depression, stress, alcoholism, illicit drug use and fatigue often can be factors in loss of sex drive in men.

Sometimes the culprit is a decrease in male sex hormones due to an endocrine disorder. In other cases, loss of sex drive may be a medication side effect.

If you're concerned about loss of sex drive — especially if the loss happened suddenly — talk to your doctor. Your doctor will likely discuss your detailed medical history, do a physical exam and request lab tests to help determine what's causing the loss of sex drive.

After identifying what's causing the loss of sex drive, your doctor can suggest treatment options. For example:

• If loss of sex drive is related to stress or depression, seeing a counselor, sometimes in combination with taking antidepressant medication, might help.

• Some medical conditions, such as obstructive sleep apnea, can cause an unusually low testosterone level. Treating the sleep apnea will reverse the low testosterone level and improve sex drive.

  If a reversible cause for low testosterone isn't found, testosterone replacement therapy might return your testosterone level and sex drive to normal.

• If a certain medication is contributing to loss of sex drive, your doctor might suggest that you take a different drug.

Some people have a hard time discussing sex with their doctors. But treatments are often available for a loss of sex drive, so it's worth it to be open with your doctor.