Few things can wipe out income, savings and a carefully constructed retirement plan more thoroughly than an accident or illness that leaves a person incapacitated. Protecting against such health care shocks is an essential part of retirement planning.

But unforeseen, out-of-pocket costs arising from a major crisis are not the only potential health-related threat to retirement security.

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There's also health care sticker shock "from the cost of premiums, deductibles and coinsurance requirements," writes AARP retirement expert Jean C. Setzfand, who used AARP's online Health Care Costs Calculator to estimate her probable tab in retirement, and found it could exceed $300,000.

"It turns out health care is a much, much larger expense than I had ever imagined — even for those with supplemental Medicare and retiree health benefits through their employer," writes Setzfand.

The $300,000 figure is not out of line with other estimates of out-of-pocket retirement costs.

Health spending also tends to increase during a person's last five to seven years of life, wealth manager Bob FitzSimmons told CNBC.

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"I have quite a few clients who have burned through their capital in assisted-living facilities, spending $200,000 to $300,000," he said.

These higher-than-expected costs cannot be wished away.

"There needs to be a better acknowledgement that paying for health care in retirement is a pretty major issue and something they need to incorporate as part of their plan," Katherine Dean, national director of wealth planning for Wells Fargo Private Bank, told USA Today.

While still working, people might also consider taking out supplemental insurance — short- or long-term disability coverage to protect earnings lost to illness or injury while still on the job. One company, PolicyGenius, offers an online "Insurance Checkup" to evaluate how protected you are.

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