Effect of pH and Sugar on the Morphology, Bulk Transparency and Thermal Characteristics of Kidney Stones

Kidney stone issues in humans have doubled since the early seventies. A variety of morphologies have been observed during stone removal from the kidney. The formation of these morphologies depends on various factors such as pH, temperature, impurities and composition of the nutrients remaining in the kidney after filtration. Growth kinetics, rate and morphology of stones depend strongly on the local concentration of insoluble species and nucleation surface in the kidney. In this paper, we have investigated the effect of pH, sugar (C6H12O6) and magnesium as an excess impurity on the kidney stone growth. At lower pH of the solution fat prism crystals are observed. Whereas at higher pH (>7), long fat needle crystals with large aspect ratio (length to width) are observed. The coarsening experiments showed further growth in different shapes. The impurity enhanced the colorization. The re-melting experiments were performed to understand the dissolution process of stones, revealing that during dissolution the joining material breaks first leaving the large faceted crystals undissolved. In addition, it was also found that the effect of excess sugar caused significant variations in the morphology and produced brown colored stones. Crystals containing sugar also retained significantly higher quantities of potassium compared to undoped stones. Finally, the effect of additional impurities e.g. magnesium on stone formation and morphology were studied demonstrating the ability to produce mushroom and cauliflower type morphologies. Thermogravimetric analysis revealed that characteristics of stones with sugar were very different, with dehydration of stones taking continuously as function of temperature.