Changes in calcium oxalate crystal morphology as a function of supersaturation

Abstract

Purpose: To study the changes in calcium oxalate crystal morphology induced by different levels of supersaturation (SS) in human urine.Materials and Methods: Twenty-four hours urine samples from 5 normal men were collected. Each specimen was centrifuged and filtered. About 200 mL of each sample was dialyzed overnight. Aliquots of 2 mL of urine was then added to a 24-wells tissue culture plate and checked for crystal absence. Calcium oxalate crystals were precipitated from each sample by adding sodium oxalate and calcium chloride in sufficient quantities to induce spontaneous crystallization. Finally, each plate hole was examined with an inverted polarized microscope (X500 magnification). Initial SS of each sample relative to calcium oxalate was calculated using an iterative computer program.Results: Crystal formation was connecte to relative calcium oxalate (CaOx) SS. At SS of 10, small crystals of similar shape were formed, mainly CaOx dihydrate morphology. At SS of 30, there was an enormous increase in the number of crystals, that kept the same size. SS greater than 50 produced larger crystals with different shapes and multiple crystalline aggregates. Urine was able to tolerate, i.e., to avoid crystal formation, until SS ratios of approximately 10.Conclusions: Relative CaOx SS and the concentration ratio of calcium to oxalate are important determinanting factors of crystal morphology. Non-dialyzable urinary proteins can act as inhibitors and influence the structure of formed crystals. Additional studies from patients with kidney stones are needed in order to establish whether crystal size and habit distribution are different from crystals in normal urine.

Antiurolithic activity of Origanum vulgare is mediated through multiple pathways

“…Calcification is a multifactorial phenomenon [44], arising as a result of a cascade of events initiated by supersaturation, including crystal nucleation, growth, aggregation and retention [45]. Although supersaturation is not the only critical step involved in the formation of kidney stones as several studies have identified many inhibitors of calcium oxalate and calcium phosphate crystallization including ionic or macromolecules [46], yet it is the prerequisite for the crystals formation in the urinary tract [47]. Various crystal inhibitors like potassium-sodium citrate and magnesium oxide have been shown to decrease the saturation of CaOx and inhibit crystal nucleation, growth and aggregation and reduced crystallization in urine of stone forming patients [48].…”

In Vitro Microscopic Study of Calcium Oxalate Monohydrate Crystals Growth Patterns

“…Calcium oxalate monohydrate are thermodynamically stable, monoclinic crystals with a P21/n space group and unit cell parameters of a 9.976 Å, b 14.588 Å, c 6.291 Å, and β 107.05°. COM are found with different morphological features as needles, prismatic, platy or platelet shaped, round edges, donut shaped, loose smaller, larger agglomerates and compact aggregates rosettes, prismatic, X-shaped crystals [17][18][19][20][21][22] . The present study was an attempt to observe the morphology and aggregation patterns of calcium oxalate monohydrate crystals and to develop an in vitro model for COM crystal growth.…”

Type 2 diabetes and uric acid stones: A powder neutron diffraction investigation

“…The former helps to describe the morphology of crystals as a function of supersaturation [77], phase conversion processes [78,79], or the effect of uric acid seeds on calcium oxalate formation [80]. Regarding in vivo studies, this technique can reveal the presence of bacteria at the surface of uroliths [81].…”