Study of renal calculi structure

There is a type of renal calculi which are build mostly of uric acid. It is currently known that these calculi occur in 13 % of nephrolithiasis cases [1,2]. The macroscopic structure and the average elemental composition of the uric acid stones have been well established [1-3]. Results collected so far showed particularly wide variability of the Ca concentration [4]. The explanation of this observation remains unknown. The investigations concerning the renal calculi growth, their microscopic structure and elemental composition are still conducted. Uric acid calculi can be divided into two groups. Type I stones develop by crystallization of uric acid from supersaturated solution with respect to uric acid anhydrous (UAA) or uric acid dehydrate (UAD). Their size ranges from several to a dozen or so millimeters. These stones have lamellar structure with small centrally located core composed of the UAA crystals. The layers develop due to variable supersaturation of urine. Thicker layers are formed slowly, when supersaturation and pH are lower, while thinner ones develop quickly, at strong urine supersaturation and high pH. A characteristic feature of type II stones is the lack of any particular inner structure. Calculi of this type are formed by sedimentation of uric acid crystals that occurs at higher supersaturation of urine. The pilot study of renal calculi observed in the recurrent nephrolithiasis was performed. To piece