But it's also not clear that using blood or urine tests to screen for chronic kidney disease causes much harm either, according to the U.S. Preventive Services Task Force.

"It's a common condition," said Dr. Joy Melnikow, a Task Force member from the University of California, Davis in Sacramento.

"I was actually struck by how little information there was."

Melnikow told Reuters Health that to recommend kidney screening, the panel would need evidence that testing healthy people - those without diabetes or high blood pressure in particular - would ultimately improve their health.

That would require both a sufficiently accurate test of kidney function as well as a proven treatment for those who test positive for kidney problems.

About one in ten adults has chronic kidney disease, in which the kidneys slowly stop being able to filter and remove waste and extra fluid from the blood.

Kidney disease typically doesn't come with any symptoms until its later stages when damage to the organs is advanced. The vast majority of people with the condition also have high blood pressure or the blood sugar disorder diabetes.

Because of that, recommendations from the American Diabetes Association, for example, call for regular kidney checks in diabetic people. But the current guidelines are only meant to cover healthy, symptom-free people without diabetes or high blood pressure.

Melnikow and the rest of the Task Force said it's unclear how accurate blood and urine tests are at measuring kidney function and how often they come back with false positives - an irregular result for what really is a working kidney.

False positives typically lead to additional testing and can cause healthy people to worry unnecessarily, researchers said.

The USPSTF also couldn't find evidence on whether treating people who are in the early stages of kidney disease but don't have symptoms does them any good in the long run.

If doctors are unsure of what they can do to help those people - and how sick they really are - labeling them with a diagnosis can be problematic, according to Dr. Ann O'Hare, a nephrologist from the University of Washington in Seattle and VA Puget Sound Health Care.

"The concern is that you're going to be telling a large number of people that they have a condition without having anything to offer them and being uncertain about the implications," O'Hare, who wasn't involved in the new guidelines, told Reuters Health.

She said the majority of people with kidney disease are elderly adults with only mildly diminished kidney function.

The new statement was published in the Annals of Internal Medicine, four months after the USPSTF released draft screening guidelines for comment on its website.

MARKETING SCREENING

In another article released in the same journal issue, researchers from the University of Oklahoma School of Community Medicine in Tulsa and the American College of Physicians point to the ethical concerns of marketing other unproven screening tests to the public.

Those direct-to-consumer tests include ultrasounds of the arteries around the heart to check for buildup, or of the heel to screen for osteoporosis.

"Patients can be coerced through unsubstantiated, misleading statements or omission of factual information into obtaining tests where the actual risk may outweigh the proven benefit," Dr. Erik Wallace and his colleagues wrote.

SOURCE: bit.ly/MnBiCA Annals of Internal Medicine, online August 27, 2012.

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