The Relative Importance of Calcium Phosphate Urinary Inhibitors
Crystal growth inhibitors may play an important role in the regulation of urinary stone formation. The major inhibitors of calcium phosphate precipitation in urine have been shown to consist of Mg, citrate and pyrophosphate (PPi) ions as well as at least one unknown low molecular weight component. Studies using diluted urines have suggested that PPi. and the unknown component are the most important calcium phosphate inhibitors1 whereas an investigation of inhibitory activity at physiological concentrations have shown that citrate and Mg are most important2. Each of these investigations, however, used an initial single addition of inhibitor and no attempt was made to maintain the fixed, steady-state concentrations of inhibiting species which are expected to exist in a system under biological control. In this study, the inhibition of calcium phosphate crystal growth is investigated at constant inhibitor concentrations so that a more realistic assessment of the relative importance of the three known calcium phosphate urinary inhibitors, Mg, citrate, and PPi. can be made.
KeywordsCrystal Growth Calcium Phosphate Physiological Concentration Seed Crystal Calcium Phosphate Precipitation
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