Kidney stones have distinct geological histories, study finds

A geologist, a microscopist and a doctor walk in a lab, with their colleagues from across the nation, make a discovery that overturns centuries of thought about the nature and composition of kidney stones. The team's key insight, reported in the journal Scientific ReportsThese are some of the most important minerals in the world, such as coral reefs or arising in hot springs, or aqueducts or subsurface oil fields.

Most importantly for human health, the researchers found, kidney stones partially dissolve and regrow again and again as they form.

This contradicts the notion of the concept of homelessness in the field of chemistry and genetic science. Bruce Fouke, MD, Ph.D. Mayo Clinic School of Medicine and Ph.D. student at the U. of I .; and Mayandi Sivaguru, associate director of the Carl Zeiss Laboratories at the Carl R. Woese Institute for Genomic Biology at the U. of I.

"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. "This means that one day we are able to fully dissolve the stones right into the patient's kidney, something most doctors today would say is impossible.

"Instead of being worthless crystalline lumps, kidney stones are a minute-by-minute record of the health and functioning of a kidney person," he said.

Sivaguru, the lead author of the microscopy study, said: "The findings were more closely related to a larger array of light microscopy and microscopy techniques. The methods included bright-field, phase-contrast, polarization, confocal, fluorescence and electron microscopy, with newly invented combinations of these tools and X-ray spectroscopy.

Many of the techniques are commonly employed in geology and geobiology, but have been used in studies of living bodies, like the kidney stones and gallstones that form in the human body, Fouke said. In particular, the use of ultraviolet light, which causes some minerals and proteins to fluoresce at different wavelengths, offered a vast new treasure trove of information.

A recently developed technology, Airyscan's super-resolution microscopy, has been shown to be much better than normal.

The effort is made in spectacularly clear, colorful images of the inner growth of the kidney stones, revealing that they are built up in alternating thin layers of organic matter and crystals, interrupted in places with jutting interior crystals.

In the earliest stages of kidney stone development, the researchers found, crystals of a hydrated form of calcium oxalate adhere to one another, forming a big, irregular clump. Layers of organic matter and crystals build up on this inner core, creating an outer shell. The stones continues to dissolve and grow. Being able to see the regions made it possible to recreate this geological history, Fouke said.

"In geology, when you see layers, that's something younger," he said. "One layer may be deposited over very long periods of time."

But many of the layers have been disrupted, revealing that part of the stones-usually the interior dihydrate crystals-had dissolved. New crystals of a dehydrated form of calcium oxalate.

"Therefore, just one rock represents a whole series of events that are critical to deciphering the history of kidney stone disease," Fouke said.

Researchers and doctors who study and treat their basic assumptions, Saw said.

"Before this study, it was thought that a kidney stone is just a crystal that gets bigger over time," she said. "What we're seeing here is that it's dynamic, it's growing and dissolving, growing and dissolving."

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More information:
Mayandi Sivaguru et al, Geobiology reveals how human kidney stones dissolve in vivo, Scientific Reports (2018). DOI: 10.1038 / s41598-018-31890-9