First reported stevia-containing human urinary calculi.

While most kidney stones are made of typical substances like calcium oxalate, patients with uncommon metabolic disorders or exposures/ingestions can crystallize rare materials in their urinary tracts, leading to unusual stone compositions. Six stones in 5 individuals were evaluated when their composition did not match known lithogenic substances. We report the first ever identified human urinary calculi composed of steviol, a metabolite of the no-calorie sweetener, stevia.