Cystine stones

Author(s):  
Michel Daudon ◽  
Paul Jungers

Cystinuria, an autosomal recessive disease (estimated at 1:7000 births worldwide), results from the defective reabsorption of cystine and dibasic amino acids (also ornithine, arginine, lysine, COAL) by epithelial cells of renal proximal tubules, leading to an abnormally high urinary excretion of these amino acids. Due to the poor solubility of cystine at the usual urine pH, formation of cystine crystals and stones ensues. Incidence of homozygotes is estimated at 1 in 7000 births worldwide, but is lower in European countries and much higher in populations with frequent consanguinity. Cystine stones represent 1–2% of all stones in adults and 5–8% in paediatric patients, with an equal distribution between males and females.Cystinuria is caused by inactivating mutations in the gene SLC3A1 or SLC7A9, both encoding proteins contributing to the function of the heterodimeric transport system of cystine.Cystine nephrolithiasis may present in infants, most frequently in adolescents or young adults, sometimes later. Cystine calculi are weakly radio-opaque. Stone analysis using infrared spectroscopy (or X-ray diffraction) allows immediate and accurate diagnosis. Urinary amino acid chromatography quantifies urinary cystine excretion, needed to define the therapeutic strategy.Urological treatment of cystine stones currently uses extracorporeal stone wave lithotripsy or flexible ureterorenoscopy with Holmium laser, that is, minimally invasive techniques. However, as cystine stones are highly recurrent, preventive therapy is essential.Medical treatment combines reduced methionine and sodium intake, to lower cystine excretion; hyperdiuresis (> 3 L/day) to reduce cystine concentration; and active alkalinization preferably using potassium citrate (40–80 mEq/day) to increase cystine solubility by rising urine pH up to 7.5–8. If these measures are insufficient to prevent recurrent stone formation, a thiol derivative (D-penicillamine or tiopronin), which converts cystine into a more soluble disulphide, should be added. Close monitoring and adherence of the patient to the therapeutic programme are needed to ensure life-long compliance, the key for successful prevention in the long term.

Nutrients ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 528
Author(s):  
Roswitha Siener ◽  
Norman Bitterlich ◽  
Hubert Birwé ◽  
Albrecht Hesse

Despite the importance of dietary management of cystinuria, data on the contribution of diet to urinary risk factors for cystine stone formation are limited. Studies on the physiological effects of diet on urinary cystine and cysteine excretion are lacking. Accordingly, 10 healthy men received three standardized diets for a period of five days each and collected daily 24 h urine. The Western-type diet (WD; 95 g/day protein) corresponded to usual dietary habits, whereas the mixed diet (MD; 65 g/day protein) and lacto-ovo-vegetarian diet (VD; 65 g/day protein) were calculated according to dietary reference intakes. With intake of the VD, urinary cystine and cysteine excretion decreased by 22 and 15%, respectively, compared to the WD, although the differences were not statistically significant. Urine pH was significantly highest on the VD. Regression analysis showed that urinary phosphate was significantly associated with cystine excretion, while urinary sulfate was a predictor of cysteine excretion. Neither urinary cystine nor cysteine excretion was affected by dietary sodium intake. A lacto-ovo-vegetarian diet is particularly suitable for the dietary treatment of cystinuria, since the additional alkali load may reduce the amount of required alkalizing agents.


Urology ◽  
2007 ◽  
Vol 69 (6) ◽  
pp. 1013-1016 ◽  
Author(s):  
Stacey G. Koff ◽  
Edmond L. Paquette ◽  
Jenny Cullen ◽  
Kevin K. Gancarczyk ◽  
Paulette R. Tucciarone ◽  
...  

Author(s):  
Michel Daudon ◽  
Paul Jungers

Uric acid (UA) stones are typically red-orange and often appear as sand/ gravel though they may be large. They are totally radiolucent. They account for about 10% of all kidney stones in most countries, and up to 20% in some populations. It is twice as frequent in males, prevalence increases with age, and it is two to three times higher in patients with type 2 diabetes or with features of the metabolic syndrome. Factors that induce the formation of UA stones are a low urine volume, hyperuricosuria, and, more importantly, a permanently low urine pH (< 5). Indeed, below its pKa of 5.35 at 37°C, UA is in non-dissociated form, whose solubility is at best 100 mg/L, whereas urinary UA excretion normally exceeds 600 mg/day and may exceed 1g/day.Because UA solubility increases up to approximately 500 mg/L at urine pH > 6, urine alkalinization, with a target pH of 6.5–7, is the cornerstone of medical treatment. This most often allows dissolution of existing stones and prevention of recurrent stone formation so that urological intervention is infrequently needed. The preferred agent for alkalinization is potassium citrate (30–60 mEq/day in divided doses), because potassium urate is twice more soluble than sodium urate. However, in patients with poor gastric tolerance to potassium citrate or contraindication to potassium supplements, sodium bicarbonate is an acceptable alternative. Limitation of animal proteins, purine-rich foods (including beer), alcoholic drinks and acidified beverages (sodas) are useful measures, together with large fluid intake (> 2–2.5 L/day). Allopurinol may be indicated in cases of symptomatic hyperuricaemia. Regular observance of alkalinisation, with periodic controls of urine pH by the patient, is needed to prevent the rapid formation of UA stones. Patients affected by UANL, especially if overweight, should be evaluated for type 2 diabetes or glucose intolerance and managed accordingly.


2001 ◽  
Vol 101 (2) ◽  
pp. 159-168 ◽  
Author(s):  
David E. FLEMING ◽  
Wilhelm VAN BRONSWIJK ◽  
Rosemary Lyons RYALL

To assess the binding of individual amino acids to the principal calcium minerals found in human kidney stones, the adsorption of 20 amino acids on to calcium oxalate monohydrate, CaHPO4.2H2O, Ca3(PO4)2 and Ca5(PO4)3OH crystals was determined over the physiological urinary pH range (pH 5–8) in aqueous solutions. All amino acids adsorbed most strongly at pH 5, and this decreased in all cases as the pH was increased. The amino acids which adsorbed most strongly were aspartic acid, glutamic acid and γ-carboxyglutamic acid, with the last displaying the strongest affinity. All amino acids bound more avidly to calcium oxalate monohydrate than to any of the phosphate minerals. Adsorption on to CaHPO4.2H2O was generally higher than for Ca3(PO4)2 and Ca5(PO4)3OH, for which all amino acids, with the exception of γ-carboxyglutamic acid, had only a weak affinity. The binding affinity of these acids is thought to be due to their zwitterions being able to adopt conformations in which two carboxyl groups, and possibly the amino group, can interact with the mineral surface without further rotation. The strong binding affinity of di-and tri-carboxylic acids for calcium stone minerals indicates that proteins rich in these amino acids are more likely to play a functional role in stone pathogenesis than those possessing only a few such residues. These findings, as well as the preferential adsorption of the amino acids for calcium oxalate monohydrate rather than calcium phosphate minerals, have ramifications for research aimed at discovering the true role of proteins in stone formation and for potential application in the design of synthetic peptides for use in stone therapy.


2021 ◽  
Vol 28 ◽  
Author(s):  
Priyadarshini ◽  
Abhishek Negi ◽  
Chetna Faujdar ◽  
Lokesh Nigam ◽  
Naidu Subbarao

Background: Human serum albumin (HSA) is one of the most abundant proteins in the blood plasma, urine as well as in the organic matrix of renal calculi. Macromolecules present in the urine modulate kidney stone formation either by stimulating or inhibiting crystallization process. Objective: In the present study, effect of HSA protein on the growth of calcium oxalate monohydrate crystal (COM) was investigated. Methods: Crystal growth assay was used to measure oxalate depletion in the crystal seeded solution in the presence of HSA. HSA concentrations exhibiting effect on crystal growth were selected for FTIR and XRD analysis. In silico docking was performed on seven different binding sites of HSA. Results: Albumin is playing dual role in growth of calcium oxalate crystallization. FTIR and XRD studies further revealed HSA exerted strain over crystal thus affecting its structure by interacting with amino acids of its pocket 1. Docking results indicate that out of 7 binding pocket in protein, calcium oxalate interacts with Arg-186 and Lys-190 amino acids of pocket 1. Conclusion: Our study confirms the role of HSA in calcium oxalate crystallization where acidic amino acids arginine and lysine are binding with COM crystals, revealing molecular interaction of macromolecule and crystal in urolithiasis.


1999 ◽  
Vol 277 (2) ◽  
pp. R482-R492 ◽  
Author(s):  
Chris M. Wood ◽  
C. Louise Milligan ◽  
Patrick J. Walsh

Exposure to hyperoxia (500–600 torr) or low pH (4.5) for 72 h or NaHCO3 infusion for 48 h were used to create chronic respiratory (RA) or metabolic acidosis (MA) or metabolic alkalosis in freshwater rainbow trout. During alkalosis, urine pH increased, and [titratable acidity (TA) −[Formula: see text]] and net H+ excretion became negative (net base excretion) with unchanged [Formula: see text] efflux. During RA, urine pH did not change, but net H+ excretion increased as a result of a modest rise in [Formula: see text] and substantial elevation in [TA −[Formula: see text]] efflux accompanied by a large increase in inorganic phosphate excretion. However, during MA, urine pH fell, and net H+excretion was 3.3-fold greater than during RA, reflecting a similar increase in [TA −[Formula: see text]] and a smaller elevation in phosphate but a sevenfold greater increase in[Formula: see text] efflux. In urine samples of the same pH, [TA − [Formula: see text]] was greater during RA (reflecting phosphate secretion), and[Formula: see text] was greater during MA (reflecting renal ammoniagenesis). Renal activities of potential ammoniagenic enzymes (phosphate-dependent glutaminase, glutamate dehydrogenase, α-ketoglutarate dehydrogenase, alanine aminotransferase, phospho enolpyruvate carboxykinase) and plasma levels of cortisol, phosphate, ammonia, and most amino acids (including glutamine and alanine) increased during MA but not during RA, when only alanine aminotransferase increased. The differential responses to RA vs. MA parallel those in mammals; in fish they may be keyed to activation of phosphate secretion by RA and cortisol mobilization by MA.


2006 ◽  
Vol 50 (4) ◽  
pp. 823-831 ◽  
Author(s):  
Ita Pfeferman Heilberg ◽  
Nestor Schor

The purpose of the present review is to provide an update about the most common risk factors or medical conditions associated with renal stone formation, the current methods available for metabolic investigation, dietary recommendations and medical treatment. Laboratory investigation of hypercalciuria, hyperuricosuria, hyperoxaluria, cystinuria, hypocitraturia, renal tubular acidosis, urinary tract infection and reduction of urinary volume is based on the results of 24-hr urine collection and a spot urine for urinary sediment, culture and pH. Blood analysis for creatinine, calcium and uric acid must be obtained. Bone mineral density has to be determined mainly among hypercalciurics and primary hyperparathyroidism has to be ruled out. Current knowledge does not support calcium restriction recommendation because it can lead to secondary hyperoxaluria and bone demineralization. Reduction of animal protein and salt intake, higher fluid intake and potassium consumption should be implemented. Medical treatments involve the use of thiazides, allopurinol, potassium citrate or other drugs according to the metabolic disturbances. The correction of those metabolic abnormalities is the basic tool for prevention or reduction of recurrent stone formation.


2009 ◽  
Vol 181 (4S) ◽  
pp. 521-522 ◽  
Author(s):  
Marnie R Robinson ◽  
Charles D Scales ◽  
Benjamin D Lack ◽  
Michael N Ferrandino ◽  
Dorit E Zilberman ◽  
...  

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