Michael reached his $1 million lifetime maximum in less than a year. The Noblesville, Ind., family had to issue a public plea for help after a hospital told them it needed either $600,000 in certified insurance or a $500,000 deposit to continue preparing for a critical bone marrow transplant.

The Treinens raised $865,000 in six days. Money came from all over the United States and as far away as Germany. But Michael's cancer had stopped responding to chemotherapy, and he died May 25 before he could receive the transplant.

The family had no idea how fast costs were piling up. Some initial bills didn't arrive until months after treatment started. Then they would receive multiple mailings for each treatment, each listing a different amount — the hospital cost, the insurance discount, the amount they owed.

"When you're dealing with constant care of your child, you're not going home with a calculator and adding up to see where you're at," Kelly Treinen said.

Insurance can shield patients from the true cost of health care, said Jerry Flanagan, health-care policy director for California-based Consumer Watchdog. He noted that most people have no idea how quickly $1 million "can evaporate," unless they've been seriously ill before.

"You can eat through a million-dollar lifetime cap in two or three surgeries," he said.

Low lifetime maximums are found more often in small-employer group plans, Flanagan said, noting that those businesses generally have less insurance-buying power. He said employers often give their workers a choice on plans or premiums but not on lifetime maximums.

The Kaiser Family Foundation study says a greater percentage of employer-offered group plans are providing lifetime caps of at least $2 million, and the percentage that offers caps below $2 million has declined slightly.

But medical costs for employer-sponsored health plans should increase 9.9 and 9.6 percent this year and next, according to PricewaterhouseCoopers Health Research Institute.

"The nature of caps is that over time it becomes easier and easier to hit (them) because the cost of health care services keeps going up," said Mike Thompson, a health care and employee benefits expert with the firm.

A coverage cap of $1 million in the 1970s would have had to grow to more than $10 million today to keep pace with rising costs, said Glenn Mones of the National Hemophilia Foundation.

The foundation's vice president for public policy says he's seen more patients approach their lifetime caps in recent years. People with hemophilia can spend more than $200,000 a year just on drugs that prevent internal bleeding.

His foundation renewed a lobbying push in Congress this year for higher lifetime caps because it sees a better political climate for one.