Solubility of inorganic kidney stone components in the presence of acid-base sensitive complexing agents.

Computation methods used to calculate the solubilities of the main inorganic kidney stone components in the absence or presence of acid-base-sensitive complexants as a function of pH are described. The solubilities of whewellite, brushite, whitlockite, octocalcium phosphate, hydroxyapatite and struvite were calculated in the presence of ethylenediaminetetraacetate (EDTA), trans-cyclohexane-1,2-diaminetetraacetate (CDTA), citrate, tripolyphosphate and alpha-hydroxyisobutyrate. The results explain why kidney irrigations with citrate give extremely variable results. The calculated solubility curves show that only EDTA and CDTA solutions with a pH of 8 or higher will have good litholytic properties for all compounds concerned. The computation methods presented in this paper can be used to calculate the solubility of a large number of salts. These salts may contain non-acid-base-sensitive cations capable of forming complexes, acid-base-sensitive anions, hydroxyl ions, hydrogen ions or other acid-base-sensitive cations (e.g. NH4+), and the solubilities can be calculated in the presence or absence of acid-base-sensitive complexing agents.