Uric Acid Urolithiasis and Crystallization Inhibitors

Abstract

An in vitro study of the inhibitory effects that some substances occasionally present in urine can provoke on the crystallization of uric acid has been performed. The most remarkable crystallization inhibitory effects were produced by mucine at concentrations of >0.5 mg/l. Pentosan polysulfate and chondroitin sulfate also clearly increased the uric acid crystallization times at concentrations of >100 mg/l. Saponins, such as escin and glycyrrhizic acid, also produced a notable delay in uric acid crystallization times at concentrations of >10 mg/l. Similar effects were observed in the presence of a surfactant substance, lauryl sulfate. N-Acetyl-L-cysteine caused crystallization perturbations only when it was present at concentrations of >50 mg/l. Citric acid and phytic acid caused no effects on uric acid crystallization even at the highest concentrations assayed (1,000 and 5 mg/l, respectively). From the results obtained it can be deduced that mainly glycoproteins, glycosaminoglycans and surfactant substances can exert protective effects against uric acid crystallization.

Thermodynamic modeling of crystal deposition in humans

“…Excessive alkalization, however, may cause precipitation of sodium or ammonium hydrogenurates [24]. The latter substance has also been found together with struvite in infectious stones caused by urea-splitting bacteria.…”

Growth of calcium oxalate monohydrate on uric acid crystals at sustained supersaturation

“…Calcium oxalate crystallizes in three hydrates in order of increasing solubility: COM, COD and calcium oxalate trihydrate (CaC 2 O 4 ·2.5H 2 O, COT) [6] The research concerning the formation of mixed calcium oxalate-uric acid stones is currently, to a large extent focused both in the clinical and in the physicochemical aspects of the process. Physicochemical investigations on crystal nucleation and crystal growth, dissolution and inhibition contribute significantly in understanding the mechanistic aspects of the pathologic minerals formation [7][8][9][10][11][12]. Because of the presence of mixed mineral phases in stones, understanding the mechanism of mixed salt formations such as calcium oxalate on uric acid substrates is of key importance for the total process control.…”

Çocuklarda Üri̇ner Si̇stem Taş Hastaliği: Tani Ve Tedavi̇ / Urinary System Stone Disease in Children: Diagnosis and Treatment

“…İdrarın bileşimi ve böbreğin anatomisi taşların oluşmasında önemli rol oynamaktadır. İdrar, kristalizasyonu kolaylaştıran ya da engelleyen maddelerin (sitrat, magnezyum, fitat ve pirofosfat iyonlar) miktarına göre kristalizasyon özelliği olan bileşiklerden (Ca, Ox, P ve ürik asit gibi) oluşmaktadır (17,18). İdrarın litojenik aktivitesi taş oluşumuna yatkınlığa neden olan faktörlerin yoğunluğu ile ilişkilidir.…”