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AUSTIN, Texas (CBS NEWS) — The high cost of medical care is giving some Americans sticker shock. Annual health care spending in the U.S. is estimated to be $3.5 trillion. Hospital costs make up almost a third of that total.

Yet there are often many inconsistencies when it comes to hospital billing. Kaiser Health News, in partnership with National Public Radio, shines light on these inconsistencies in its “Bill of the Month” series.

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This month, the series takes a look at Drew Calver, who was hospitalized last year in Austin, Texas, for a heart attack. His treatment included four stents in his arteries.

drew calver Man Battles $109,000 Hospital Bill, Gets Discount After Heart Attack

Credit: CBS3.

Calver has health insurance through a teaching job, which covered about $55,000 of the bill. But a month after his treatment, Calver received a bill for nearly $109,000.

He and his wife Erin were confused and frustrated by the medical bills at a time when Calver needed to be concentrating on his health.

“My focus should be staying healthy and preventing another heart attack,” Calver said.

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“You do all this to save a person’s life and then you’re making their lives a living nightmare,” his wife Erin added.

The hospital where he was treated, St. David’s Medical Center, issued the following statement to CBS News and Kaiser Health News: “Our research indicates that Mr. Calver will qualify for our financial assistance discount, leaving him with a balance of less than $800.”

medical center statement Man Battles $109,000 Hospital Bill, Gets Discount After Heart Attack

Credit: CBS3.

The hospital said it offered Calver the opportunity to apply for financial assistance several times and that the “charges reflect the ‘retail’ price for a procedure, treatment, or visit.”

So how do medical bills get so high in the first place? Dr. Elizabeth Rosenthal, editor-in-chief of Kaiser Health News, explains that the prices hospitals charge are “kind of arbitrary.”

“They can be anything. They pull them out of thin air,” she told “CBS This Morning.” “I have to say I looked at this bill and the prices for every line-item were just exorbitant. $200 for a blood test. $20,000 for one single stent. We looked into that and those stents probably cost $1,000, so there’s mark-up on everything.”

It’s important to keep in mind that Calver had insurance, too, Rosenthal points out. However, because the hospital where he was treated was out-of-network, he was subject to what’s referred to as “surprise billing” in which normal insurance protections don’t apply.

hospital bill Man Battles $109,000 Hospital Bill, Gets Discount After Heart Attack

Credit: CBS3.

“What we have here is a really common situation in American medicine in which the hospital and insurer disagree on a price and the patient gets left holding the bag for the difference,” Rosenthal said.

But patients do have some negotiating power.

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“My first piece of advice to people is don’t write the check. You have some agency. You have some power,” Rosenthal said.

The first step is to get an itemized bill so you know exactly what you’re being charged for. Then go in and negotiate. Rosenthal offers some tools to help.

“You can look on Healthcare Bluebook or look at what Medicare pays, and you can go in and say to someone who’s trying to charge you $100,000 that this is ridiculous and way above the norm,” she said.