An itsy-bitsy cause of kidney stones


Kuopio, Finland

While it's no secret that kidney stones can be excruciating, the reason the craggy clumps form has been a mystery. Some scientists now suspect they've nabbed the guilty party: newly discovered microbes called nanobacteria.

These slow-growing bacteria are far teenier than most, says University of Kuopio physician Olavi Kajander. Curiouser still, they sometimes grow a hard, grayish-brown shell composed of a calcium-rich compound. Since most kidney stones are also made of calcium, Kajander hit on a theory: The painful pebbles might result from calcium crystals building up layer by layer atop the bacteria's lilliputian armor. In a recent study he and a colleague found evidence supporting the idea. Upon scrutinizing 30 stones from patients, the scientists found the microbes in every one.

"The theory is certainly interesting and potentially important," says Gary Curhan, a kidney specialist at Massachusetts General Hospital in Boston, who cautions that more research is needed to confirm the finding. If the bugs truly are the instigators, a course of antibiotics might prevent kidney stones from recurring.


By Christie Aschwanden; Ingfei Chen and Rachele Kanigel

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