Fluorescence micrograph of a human kidney stone from the Mayo Clinic.
Mayandi Sivaguru, Jessica Saw from Bruce Fouke Lab, Carl R. Woese Institute for Genomic Biology, U. of I.
Recent research found that kidney stones have many more similarities with real stones than anyone previously thought. The team of both medical students and geologists were able to piece together how kidney stones form, their changes through time, and how they can record the health of a person's kidney.
The research, published in Scientific Reports, upends our understanding of how kidney stones grow. Kidney stones grow much like coral reefs or stalagmites grow, adding sequential calcium carbonate layers on top of each other. In between growth cycles, kidney stones can also dissolve slightly, leaving gaps in their structure.
In geology, rocks can unlock clues to the environments they were exposed to. For example, a stalagmite grows in size by the slow drip of mineral-rich water in a cave. Each water droplet contains dissolved minerals, which precipitate out to add a tiny amount rock to a stalagmite.
As calcium carbonate layers form from the sequential drip of mineral-rich waters, trace elements within the water record changes in Earth's environment. For example, by analyzing the oxygen isotopes within the calcium carbonate layers, scientists can determine the precipitation record in the surrounding region.
A 2,000-year-old stalagmite with layers of calcium carbonate corresponding to the wet and dry season each year. Scientists can detect tropical cyclones in these layers from very depleted levels of oxygen-18.
Much like these rocks, kidney stones grow through time, layer by layer and in doing so record the health of a person's kidneys. Kidney stones are primarily made up of calcium oxalate, which was previously thought to be insoluble within the kidney. However, through analyzing kidney stones using geological approaches, the team was able to identify dissolution zones within the crystals.
This indicates that the kidney stones both grow and dissolve as time passes. The breakthrough in understanding could lead to proactive measures to dissolve kidney stones instead of painfully passing or surgically removing the stones.
A human kidney stone from the Mayo Clinic.
The research team concluded in their paper that kidney stones could be used to read a minute by minute history of a person's health, similar to how geologists read rock layers to understand past environments.
By investigating kidney stones under X-Ray spectroscopy and fluorescence microscopes, tools typically used in geology, the team was able to see unprecedented detail with resolutions up to 140 nanometers.