Urinary stone analysis in a patient with hyperuricemia to determine the mechanism of stone formation

In order to determine the mechanism of urinary stone formation in patients with hyperuricemia, we analyzed the crystal components and matrix proteins in a urinary stone from such a patient. Micro-area X-ray spectrometry and infrared (IR) spectroscopy suggested that the outside of the stone was composed of calcium oxalate monohydrate (COM) and the inside of uric acid (UA). Proteomic analysis identified 37 and 14 proteins from the inside and outside of the stone, respectively, as matrix proteins. The proteins that were identified in an ethylenediaminetetraacetic acid (EDTA) fraction were able to bind calcium ions. Thus, calcium-binding proteins may play a significant role in the formation of urinary stones in patients with hyperuricemia.