Kinetics of calcium oxalate crystal formation in urine

Abstract

It is routinely observed that persons with increased urinary stone risk factors do not necessarily form uroliths. Furthermore, stone formers can present with urinalyses that do not reflect the clinical picture. We explain this discrepancy by differences in crystallization kinetics. In 1162 urines, crystallization of Ca-oxalate was induced according to the BONN-Risk-Index (BRI) method. The urine's relative light transmissivity (RLT) was recorded from 100 % at start of titration to 95 % due to nuclei formation and crystal growth. From the RLT changes, a measure of the thermodynamic inhibition threshold of crystal formation (BRI) and of crystal growth kinetics is derived ("turbidity slope" after crystallization onset). On average, subjects presenting with a low inhibition threshold, i.e., high BRI, also present significantly higher crystal growth rates compared with subjects in lower BRI classes. Only subjects in the highest BRI class show a lower growth rate than expected, probably due to a depletion of supersaturation by massive initial nucleation. With increasing thermodynamic risk of crystal formation (i.e., increasing BRI) due to an imbalance between inhibitors and promoters of crystal formation, an increase in the imbalance between inhibitors and promoters of crystal growth (i.e., increasing growth rate) is observed. Both lead to an increased urolith formation risk. Healthy subjects with increased BRI are an exception to this trend: their urine is thermodynamically prone to form stones, but they show a kinetic inhibition preventing nuclei from significant growth.

Effect of Functionalized Multiwalled CNTs on the Selective Formation of Calcium Oxalate Crystals by Electrocrystallization

“…Citrate and MWCNT-IA, which are both anionic compounds, can bind Ca 2+ ions during the EC of CaOx in a better way than MWCNT-MMI and MWCNT-MODI. This is why it is very important to analyze the electrochemical solution to determine the amount of Ca 2+ in solution and to understand how urinary molecules prevent the formation of KS . We state that the experimental conditions are indicators of the modulation of the EC of CaOx.…”

“…This is why it is very important to analyze the electrochemical solution to determine the amount of Ca 2+ in solution and to understand how urinary molecules prevent the formation of KS. 39 We state that the experimental conditions are indicators of the modulation of the EC of CaOx. MWCNTs induced changes in the morphology and acted in an active way to control the nucleation and growth of CaOx crystals.…”

The protective role of corilagin on renal calcium oxalate crystal‐induced oxidative stress, inflammatory response, and apoptosis via PPAR‐γ and PI3K/Akt pathway in rats

“…Thus, the renal tubules’ injured cells and the microvilli are damaged to progress into disintegration [23]. These damaged parts of the renal tubules move from the cytoplasm to the lumen, where they act as “seeds” or nuclei for the initiation of the CaOx crystals formation [24]. Thus, ROS‐induced free radicals are released from the mitochondrial electron transport chain, and nicotinamide adenine dinucleotide phosphate oxidase plays a significant role in the formation of crystals [25].…”

Potential Markers of Recurrency of Urolithiasis Disease and the Role of Stone Formation Inhibitors in Recurrent Calcium Oxalate Nephrolithiasis

“…IαI и родственные ему молекулы, известные как семейство IαI, имеют отношение к различным патологическим состояниям, таким как воспалительные заболевания, рак, почечная недостаточность и мочекаменная болезнь. Белки семейства IαI ингибируют кристаллизацию оксалатов кальция in vitro [48]. Воздействие этих кристаллов на эпителиальные клетки почек приводит к увеличению экспрессии мРНК бикунина.…”