Many doctors in the U.S. are going broke, according to CNNMoney.

This is happening to doctors across the nation, including cardiologists, family physicians and oncologists.

Watchers of the health care industry say the trend gives them concern, according to CNNMoney. About 50 percent of all doctors in the U.S. have a private practice. So if a practice goes out of business, it can leave a community without a critical health care resource.

Marc Lion, CEO of Lion & Company CPAs, LLC, which advises independent doctor practices about their finances, told CNNMoney that a lot of independent practices are starting to have serious financial issues.

Doctors have listed changing regulations, rising drug and business costs and shrinking insurance reimbursements among other factors that are causing their practices to go out of business. Some experts say doctors' lack of business insight is also a factor, according to CNNMoney.

Dr. William Pentz, 47, a cardiologist with a private practice in Philadelphia, and his partners had to use some of their own money to make payroll for their employees in 2011, according to CNNMoney.

Pentz told CNNMoney that recent 35 to 40 percent cuts in Medicare reimbursements for fundamental cardiovascular services like stress tests and echocardiograms have had a large effect on revenue in 2011. Revenue for Pentz's practice was down 9 percent in 2011 compared to 2010.

"These cuts have destabilized private cardiology practices," Pentz told CNNMoney. "A third of our patients are on Medicare. So these Medicare cuts are by far the biggest factor. Private insurers follow Medicare rates. So those reimbursements are going down as well."

There is an impending 27.4 percent Medicare pay cut for doctors. Pentz told CNNMoney that if the pay cut occurs, it will put his practice out of business.

Federal law requires that Medicare reimbursement rates be adjusted annually based on a formula tied to the economy. This law states that rates should be cut every year so that Medicare will be financially sound.

The federal government spends about 50 percent of all health care money in the country, and many health insurance companies base their reimbursements on what the government does, according to PressTV.

Even though medical practices are shutting down across the country, doctors' pay is still in the range of six-figures, according to an MGMA survey.

Radiologists' median income was about $471,000, a decrease of 1.5 percent. But the median income for physicians in internal medicine was about $205,000, an increase of 4.2 percent since 2009.