Kidney stones, the painful urinary deposits that affect more than 10 percent of people worldwide, are surprisingly dynamic, forming much like microscopic coral reefs, according to new research that could provide insights into how to better diagnose and treat the condition.
The findings, published last week in the journal Scientific Reports, challenge assumptions by many doctors that kidney stones are homogeneous and insoluble. Instead, they resemble nanoscale coral reefs or limestone formations: complex, calcium-rich rocks with strata that accumulate and dissolve over time, researchers found.
“When doctors find that ugly, boring lump and discard it, they are throwing away the most precise record book we have — a minute-by-minute, layered history of the kidney’s physiology,” said Bruce Fouke, a geology and microbiology professor at the University of Illinois, who led the project.
Dr. Brian Matlaga, a urologist and kidney stone surgeon at Johns Hopkins, called the study “a provocative, outside-the-box approach” to a burdensome health issue.
“When we break up kidney stones surgically, some of them are indeed quite beautiful — like a geode, like the rings on a tree, or something you’d hang on your wall,” Dr. Brian Matlaga said. “So research into this is very exciting — it’s very novel to the field.”
Dr. Fouke, whose research projects have taken him skiing through Yellowstone National Park and scuba-diving in Australia’s Great Barrier Reef, saw early connections between human kidney stones and the coral skeletons, hot spring travertine and even oil and gas migration deep below the planet’s surface: Interactions between living things, water and mineral growth occur in all three.
“The water that comes out of Yellowstone springs is hot and salty — much like seawater, and, yes, urine,” he said. As for the intricate stone deposits that these liquids help form, “You wouldn’t be able to tell them apart under a microscope.”
Dr. Fouke and his fellow researchers examined more than 50 kidney stone fragments from six Mayo Clinic patients using various light and electron microscopes. They identified organic matter and calcium crystals with ultraviolet light, which uses different wavelengths to make distinct minerals glow.
A high-resolution method, called Airyscan super-resolution microscopy, captured colorful snapshots of organic matter and crystal layers in the kidney stones, “crosscut and truncated” by newer crevices, triangles and other geometrics, Dr. Fouke said. The disruptive patterns in the stones showed that the vast majority of the material had dissolved and reformed over time.
Doctors often base patient care plans upon the chemistry and molecular components of a patient’s urine. But further research could allow doctors to take advantage of the changing composition of kidney stones themselves, boosting specific ingredients to dissolve the stones completely, without excruciating passage or invasive procedures.
“Now that we know a process by which they’re growing, the question is, how can we flip the switch the other way, and break the stones down?” said Dr. Matlaga, the surgeon. “If you can intervene at a certain time during these events, you might be able to manipulate the process by which the stones are growing.”
The study credits centuries of revolutionary geologists for inspiring its hypothesis — most importantly, Nicholas Steno, a Danish anatomist who, in 1667, proposed that layered rock could indicate a chronological history of events. (He allegedly died of kidney stones.)
Follow Emily Baumgaertner on Twitter: @Emily_Baum
