Kidney Stones Sometimes Dissolve Naturally, Raising Hopes For New Treatments

A transect through a kidney stone has revealed the way they are built up. Mayandi Sivaguru, Jessica Saw from Bruce Fouke Lab, Carl R. Woese Institute for Genomic Biology, U. of Illinois

It's not often that medical students and geologists combine, but one such collaboration has overthrown a key belief about kidney stones. Their teamwork may help ease the pain of these agonizing menaces.

Kidney stones' name is more than just an analogy. They are formed from calcium-rich layers in a manner similar to coral reefs, and bear a strong resemblance to many rocks. This similarity led University of Illinois Geology Professor Bruce Fouke to study them, working with Jessica Saw, who is doing a PhD in biomineralization at the same university, while taking leave from medical studies.

“Contrary to what doctors learn in their medical training, we found that kidney stones undergo a dynamic process of growing and dissolving, growing and dissolving,” Fouke said in a statement

The finding has important implications, the researchers argue in Scientific Reports. Most obviously, the processes that can cause kidney stones to shrink might one day be harnessed to reduce the size of stones too large to pass, or even eliminate them altogether. With 9 percent of the world susceptible to kidney stones, the benefits for pain-free living could be extensive.

Moreover, the discovery indicates the stones might even serve a diagnostic purpose. “Instead of being worthless crystalline lumps, kidney stones are a minute-by-minute record of the health and functioning of a person’s kidney,” Fouke said.

To demonstrate this, Fouke, Saw, and co-author Dr Mayandi Sivaguru studied more than 50 kidney stones under a dazzling array of microscopes and light sources. X-Ray spectroscopy and fluorescence microscopes, among many others, are well-established tools in geology but have not previously been applied to the minerals we produce within our bodies, including kidney and gallstones.

A fluorescence micrograph of part of a kidney stone Mayandi Sivaguru, Jessica Saw from Bruce Fouke Lab, Carl R. Woese Institute for Genomic Biology, U. of I

By viewing stones to a resolution of 140 nanometers (0.000006 inches) the authors we able to show the stones begin as crystals of hydrated calcium oxalate, which then become encased in successive layers of organic material and further crystals, sometimes with larger crystals jutting out in one direction.

The key insight, that stones sometimes partially dissolve, was observed from the way interior components, particularly the crystals at the stones' core, have sometimes broken down. The spaces then become filled with new calcium oxalate crystals, but these ones have much lower water content than the originals.

Besides finding ways to accelerate this dissolution, the authors suggest we might be able to prevent stones forming at all by disrupting the biological processes that lead to switching between the production of organic and crystal layers.

If you can forget the pain, kidney stones are quite beautiful under microscopes. Dark layers are rich in organic matter, lighter ones made from calcium oxide crystals. Sivaguru et al/Scientific Reports

 

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