Studies on Calcium Oxalate Crystal Formation in Urolithiasis Multi-Regressive Analysis of Urinary CaOx Crystalline Volumes and the Effects of Urinary Various Substances on CaOx Crystal Formation

Abstract

Because human urine contains various substances which can affect each other, it is quite difficult to clarify the mechanism of formation of calcium oxalate (CaOx) crystal in urine. The authors recently determined CaOx crystalline content and the concentrations of other substances in urine specimens from patients with urolithiasis and healthy volunteers, and subjected the data to multi-regressive analysis for the purpose of assessing the effect of these urinary substances on CaOx crystal formation. 1. In analysis of urine from patients with urolithiasis, the partial correlation coefficients of CaOx crystal formation with oxalic acid, sodium, calcium, uric acid magnesium were 0.67, 0.28, 0.18, and —0.10, respectively. The formula of regression was as follows: Amount of CaOx crystal (× 106 μm3/ml)=3.59 × 10-2Ox (mM/L) + 4.72 × 10-3 Ca (mM/L) + 4.52 × 10-3 Na (mM/L) + 2.51 × 10-4 UA (mM/L) -2.39 × 10-2 Mg (mM/L) -1.65 The multiple correlation coefficient was 0.759. Thus, in patients with urolithiasis, urinary crystal formation was most dependent on the oxalic acid level, sodium, calcium, and uric acid were found to promote crystal formation, while magenesium to suppress it. 2. In analysis of urine from healthy volunteers, the partial correlation coefficients of CaOx crystal formation with oxalic acid and inorganic phosphorus were 0.51 and —0.24, respectively. The formula of regression was as follows: Amount of CaOx crystal (× 106 μm3/ml)=1.91 × 10-2 Ox (mM/L) -3.43 × 10-4 P (mM/L) + 0.29 The multiple correlation coefficient was 0.525. Thus, also in urine from healthy volunteers, crystal formation was dependent on the oxalic acid level, but no other factors promoting crystal formation was identified. Inorganic phosphorus was found to suppress crystal formation in urine from healthy volunteers. The low multiple correlation coefficient in healthy volunteers as compared to that in patients with urolithiasis suggests that many unknown substances are involved in crystal formation. © 1991, THE JAPANESE UROLOGICAL ASSOCIATION. All rights reserved.