Experimental Investigations and Numerical Assessment of Renal Calculi and its Management

Abstract

Kidney stone diseases (KSD) have become more common in developed countries over the last few decades. By 2050, global KSD prevalence may reach 30%. Depending on the type of stone, kidney stone formation might be complicated. Calcium oxalate, uric acid, calcium phosphate, and magnesium ammonium phosphate are found in kidney stones in various amounts. Among these substances, calcium oxalate (CaOx) stones account about 80% of urinary stones followed by uric acid. However, in literature little attention has been given to uric acid stones despite accounting for 8 10% of the kidney stones. The crystallization of urinary solutes is considered as the beginning of the development of kidney stones. Understanding the effect of physiological parameters on the crystallization of urinary solutes help us in identifying the potential risk factors of kidney stone development. Considering this, the present work discusses crystallization of uric acid as a kidney stone forming component. newlineThe study initially focused on batch crystallization of uric acid. Crystallization was carried out in jacketed crystallizers thermostated at 37°C, with the provision of magnetic stirring. Factors such as solution pH, initial uric acid concentration, and stirring were examined to understand their impact on crystal size and the induction time of UA crystallization. Results showed that increasing solution pH led to larger crystal size and longer induction time due to reduced uric acid supersaturation. An increase of 10 folds in induction time and 1.6 folds in crystal size was observed on changing the pH from 3 to 5. Crystal size also increased when stirring was absent, with stagnant solutions producing crystals at least five times larger than stirred ones. The kinetics of crystallization (nucleation and growth) was analyzed by solving population balance equation, where simulation results revealed that both processes show second-order kinetics. newlineWith the suitable physiological conditions, certain substances are known to promote the formation of kidney