Quantification of crystal growth of calcium oxalate in gel and its modification by urinary constituents in a new flow model of crystallization.

Abstract

To use a new flow model of crystallization to quantify the growth of calcium oxalate monohydrate (COM) in a gel matrix under simulated physiological conditions. Artificial urine supersaturated in COM was conducted through channels containing a gel with COM seed crystals (flow rate: 0.5 ml. per minute; reaction time: 4 hours; 37 +/- 1C). A relative crystal growth parameter, Vcr, was quantified by discontinuous measurement of scattered light intensity by microphotometry. The effects on Vcr of varying a series of urinary parameters were investigated within the system. The following order of effectiveness in changing COM growth could be derived: dilution > oxalate > calcium > magnesium approximately citrate. Drinking therapy and lowering of urinary oxalate excretion can be concluded to be the most promising means of preventing CaOx urolithiasis. The new crystallization model demonstrated here should be suitable to new applications in the investigation of urinary stone formation.