What are kidney stones?
One of the most common disorders of the urinary tract, kidney stones (renal calculi) are solid pieces of material that form in the kidney from substances in urine. They can be so small as to be invisible to the naked eye, or as big as a pearl. Kidney stones lead to almost three million visits to health care providers and more than half a million emergency room visits annually.
The incidence of kidney stones in the United States has been increasing over the past 30 years for unknown reasons. From less than four percent . . .