Uric acid dihydrate as urinary calculus component.

The analysis of uric acid dihydrate was performed using infrared spectroscopy and X-ray diffraction. Both methods permit differentiation with regard to uric acid. Pure uric acid dihydrate was prepared according to a modified technique and the dA values (lattice distances (of A) were determined from several recordings. The extreme instability of the synthetic uric acid dihydrate is stressed, and the conversion speed is determined. During the evaluation of 7,750 analyses of urinary calculi in the course of the past 3 years, 1,126 (14.5 per cent) uric acid calculi and 283 (3.7 per cent) with a mixed portion of uric acid dihydrate were found.