Thermodynamic modeling of crystal deposition in humans *

The prevention and treatment of crystal deposition in the human body are based on the understanding of the physicochemical properties underlying the precipitation of the substances involved. Among these properties, the solubilities of the crystals are very important. Recently, experimentally determined solubility data of substances related to urolithiasis, such as calcium oxalate hydrates, uric acid and urates, cystine, and xanthine, were critically assessed. Unfortunately, reported solubilities of these substances were found to be either scarce or in large disagreement. Consequently, detailed studies were carried out in our laboratory, and the results will be discussed in this communication with emphasis on the thermodynamic consistency of the experimentally determined data. Since proper modeling of the solubilities of these substances in artificial urine solutions serves as a prerequisite for solubility predictions in real urine, the Joint Expert Speciation System (JESS) software package was employed to create a comprehensive computer model including the relevant, low-molecular inorganic and organic components of urine. The results of the simulations lead to some useful suggestions regarding the prevention and treatment of stone disease.