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Query: UMLS:C0451641 (urolithiasis)
 3,973 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Urine activity product ratios of uric acid, sodium urate, and ammonium urate and urinary excretion of metabolites were determined in 24-hour samples produced by 6 healthy Beagles during periods of consumption of a low-protein, casein-based diet (diet A) and a high-protein, meat-based diet (diet B). Comparison of effects of diet A with those of diet B revealed: significantly lower activity product ratios of uric acid (P = 0.025), sodium urate (P = 0.045), and ammonium urate (P = 0.0045); significantly lower 24-hour urinary excretion of uric acid (P = 0.002), ammonia (P = 0.0002), sodium (P = 0.01), calcium (P = 0.005), phosphorus (P = 0.0003), magnesium (P = 0.01), and oxalic acid (P = 0.004); significantly (P = 0.0001) higher 24-hour urine pH; and significantly (P = 0.01) lower endogenous creatinine clearance. These results suggest that consumption of diet A minimizes changes in urine that predispose dogs to uric acid, sodium urate, and ammonium urate urolithiasis.
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PMID:Diet effect on activity product ratios of uric acid, sodium urate, and ammonium urate in urine formed by healthy beagles. 777

Naturally occurring glycosaminoglycans (GAGs) and other, semisynthetic, sulphated polysaccharides are thought to play an important role in urolithiasis. Processes involved in urinary stone formation are crystallization and crystal retention. Oxalate transport and renal tubular cell injury are determining factors in these processes. In this article experimental results concerning the possible mechanisms of action of GAGs and other sulphated polysaccharides are reviewed. GAGs are inhibitors of crystal growth and agglomeration and possibly also of nucleation. They can prevent crystal adherence, correct an abnormal oxalate flux and prevent renal tubular cell damage.
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PMID:Glycosaminoglycans and other sulphated polysaccharides in calculogenesis of urinary stones. 801 15

Evidence for the suitability of spot urines for selective screening in children was obtained by comparing the 24-hour urinary oxalate excretion with the ratio of urinary oxalate to creatinine [mmol/mol] in spontaneously voided urine samples. Spot urines of 169 healthy children aged 1 day to 13 years were analysed in order to establish reference values for the urinary oxalate/creatinine ratio in relation to age and body surface area. Oxalate was measured by automated ion chromatography. Results showed an inverse relationship between the oxalate/creatinine ratio and age. The highest ratios, 131 +/- 57 mmol/mol (mean +/- 2 SD), were found in infants. At age two years, the ratio was 84 +/- 55, at age five years 56 +/- 35, and for children older than ten years 42 +/- 31. This finding can be explained by the gain of muscle mass and hence increased creatinine production with increasing age. Data for the urinary oxalate/creatinine ratio are presented according to body surface area for the assessment of children with abnormal growth. In 19 urine samples from nine patients with primary hyperoxaluria, the oxalate/creatinine ratio greatly exceeded (286-2022 mmol/mol) the above reference ranges. We therefore propose the determination of the oxalate/creatinine ratio in spot urines for the selective screening for hyperoxaluria in children with nephrocalcinosis or urolithiasis.
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PMID:Determination of oxalate excretion in spot urines of healthy children by ion chromatography. 816 90

The possibility that dietary fish oil supplementation may benefit patients with hypercalciuric urolithiasis by decreasing calcium excretion and enhancing protective mechanisms has been studied in rats and humans. In experiments on rats in metabolic cages, fish oil inhibited experimental nephrocalcinosis induced by intraperitoneal calcium gluconate. There were no significant changes in urinary biochemistry. In a clinical study on 18 hypercalciuric recurrent stone patients fish oil significantly decreased urinary calcium excretion. This effect was accompanied by decreases in the excretion of magnesium and citrate. Oxalate excretion and urinary fibrinolytic activity were unchanged. Overall, fish oil had a limited impact on the risk profile for recurrent urolithiasis.
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PMID:Does fish oil benefit stone formers? 841 6

Urolithiasis is one of the most frequent causes of morbidity in developed countries and its incidence is close to 5%. In our experience, 67.4% of urinary stones contain calcium oxalate as the main component, and hyperoxaluria plays an important role in the pathophysiology of this type of stone. The mechanisms responsible for the increment in urinary excretion of oxalate could involve oxalic acid synthesis. This increase could be due either to an increment of its endogenous formation or to an exogenous load of its precursors. Furthermore, an increased intestinal oxalate absorption is a frequent cause of hyperoxaluria and urolithiasis. Ingestion of oxalate rich foods, imbalance in the supply of other nutrients that influence oxalic acid absorption and GI disorders with malabsorption and/or decreased degradation of intraluminal oxalate can increase intestinal oxalate transport and cause hyperoxaluria. In this article we review the physiological mechanisms that control the oxalate pool: endogenous synthesis, exogenous supply, intestinal absorption and renal excretion of oxalic acid. We analyze the causes and the pathophysiological mechanisms that increase urinary oxalate excretion. We describe a protocol for the biochemical study of patients with hyperoxaluria and the therapeutic measures to reduce urinary oxalate are reviewed. Finally, possible research that may provide further insight into oxalate metabolism in patients with hyperoxaluria are discussed.
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PMID:[Hyperoxaluria and renal calculi]. 902 8

To determine reference values, we studied urinary excretion of oxalate prospectively and longitudinally in a cohort of 23 very-low-birth-weight (VLBW) infants. The urinary oxalate concentrations were evaluated in 24-hour urine samples by the oxalate oxidase method. Urine samples were obtained at 1, 2-3, 4-5 and 6-7 weeks of age. The median oxalate amount was 24 mumol/kg body weight/day with a 10th-90th percentile range of 16-45 in the 1st week. Oxalate excretion was highest in 2- to 3-week-old infants (median: 35; percentile range: 26-56 mumol/kg body weight/day). In the 4th-5th week, the median was 24 (percentile range: 15-47) mumol/kg body weight/day and in weeks 6-7 also 24 (percentile range: 10-36) mumol/ kg body weight/day. Also, the urinary oxalate concentration as well as the oxalate-creatinine ratio showed increased values in the first 3 weeks of life and decreased values afterwards. In a multivariate analysis, nutrition or gestational age did not affect the urinary oxalate concentration, the daily amount excreted or the oxalate-creatinine ratio. The investigated parameters (oxalate amount and oxalate-creatinine ratio in urine) were significantly age dependent). The data show that urinary oxalate excretion in VLBW infants approaches levels that are in the same range as those of patients with urolithiasis. Thus the risk of nephrocalcinosis in VLBW infants may be increased.
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PMID:Oxalate excretion during the first 7 weeks in very-low-birth-weight infants. 916 48

In up to one-third of patients with calcium oxalate stones, a hyperoxaluria can be detected. Hyperoxaluria can result from increased endogenous production, from excessive oxalate content of the food, or from intestinal hyperabsorption. For a causal therapy, it is important to discriminate between metabolic and hyperabsorptive hyperoxaluria. Our new 13C-oxalate test allows this differentiation. Under standardized conditions, 50 mg of disodium salt of [13C2]oxalic acid was applied. From the amount of labeled oxalate excreted in urine as measured by a gas chromatographic-mass spectrometric assay, the intestinal absorption was calculated. Seventy patients with recurrent calcium oxalate urolithiasis who had no signs of inflammatory bowel disease were tested. Their mean intestinal oxalate absorption was 9.2+/-5.1%. This was significantly higher than the mean absorption of 50 healthy volunteers (6.7+/-3.9%). There was no difference in oxalate absorption between male (n = 25) and female volunteers. Oxalate absorption correlated with the oxalate excretion in the 24-h urine (volunteers: r = 0.46, P < 0.01; patients: r = 0.62, P < 0.001). Oxalate hyperabsorption was defined as an absorption exceeding 10%. According to this definition, 34% of the patients had oxalate hyperabsorption; 20% of the volunteers showed a hyperabsorption, too. The 13C-oxalate absorption test allows reliable determination of intestinal oxalate absorption. Because of the use of a stable isotope, this test may be repeated as often as required. It will allow the control of therapeutic regimens and also help to unravel genetic influences in stone formation.
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PMID:Intestinal hyperabsorption of oxalate in calcium oxalate stone formers: application of a new test with [13C2]oxalate. 1054 Dec 57

The evaluation of urinary oxalate excretion is one of the most important diagnostic methods in patients with urolithiasis and/or nephrocalcinosis. Since reliable 24-h urine collections are difficult to obtain in children, excretion ratios of oxalate over creatinine are increasingly being used from single urine specimens. The aim of the study was to determine the normal values of oxalate/creatinine ratios in the second morning urine sample in healthy school children. The study involved 109 children between 6 and 16 years of age. The results showed that the values of Ox/Cr ratios are decreased in older children and there was significant difference between children under and above 12 years of age (values of the 95th percentile--0.076 and 0.051 mmol/mmol respectively). The significant correlation between 24-hours urinary oxalic acid excretions and Ox/Cr ratios (r-0.756) was found. We conclude, that Ox/Cr ratio is valuable parameter for screening purposes in children.
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PMID:[Evaluation of oxalate/creatinine ratio in the second morning urine sample of health school children]. 1143 74

Membrane injury facilitated the fixation of calcium oxalate crystals and subsequent growth into kidney stones. Oxalate-induced membrane injury was mediated by lipid peroxidation reaction through the generation of oxygen free radicals. In urolithic rat kidney or oxalate exposed cultured cells, both superoxide anion and hydroxyl radicals were generated in excess, causing cellular injury. In hyperoxaluric rat kidney, both superoxide and H2O2-generating enzymes such as glycolic acid oxidase (GAO) and xanthine oxidase (XO) were increased, and hydroxyl radical and transition metal ions, iron, and copper were accumulated. The lipid peroxidation products, thiobarbituric acid-reactive substances (TBARS), hydroperoxides, and diene conjugates were excessively released in tissues of urolithic rats and in plasma of rats as well as stone patients. The accumulation of these products was concomitant with the decrease in the antioxidant enzymes, superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), and glucose-6 phosphate dehydrogenase (G6PD) as well as radical scavengers, vitamin E, ascorbic acid, reduced glutathione (GSH), and protein thiol. All the above parameters were decreased in urolithic condition, irrespective of the agents used for the induction of urolithiasis. Oxalate binding activity and calcium oxalate crystal deposition were markedly pronounced, along with decreased adenosine triphosphatase (ATPase) activity. Lipid peroxidation positively correlated with cellular oxalate, oxalate binding, gamma-glutamyl carboxylase, and calcium level and negatively correlated with GSH, vitamin E. ascorbic acid, and total protein thiol. Antioxidant therapy to urolithic rats with vitamin E, glutathione monoester, methionine, lipoic acid, or fish oil normalised the cellular antioxidant system, enzymes and scavengers, and interrupted membrane lipid and protein peroxidation reaction, ATPase inactivation, and its associated calcium accumulation. Antioxidant therapy prevented calcium oxalate precipitation in the rat kidney and reduced oxalate excretion in stone patients. Similarly, calcium oxalate crystal deposition in vitro to urothelium was prevented by free radical scavengers such as phytic acid and mannitol by protecting the membrane from free radical-mediated damage. All these observations were suggestive of the active involvement of free radical-mediated lipid peroxidation-induced membrane damage in the pathogenesis of calcium oxalate crystal deposition and retention.
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PMID:Calcium oxalate stone disease: role of lipid peroxidation and antioxidants. 1194 24

Urolithiasis is a common clinical disorder. Its frequency has risen with the development of humanity and varies wirl the country, geographic area, etc. It poses health problems in most countries. The urolithiasis has some potential risk factors such as intrinsic and extrinsic epidemiological, metabolic, physic-chemistry of the urine, mechanics and urinary infection. Our objective in this epidemiological study in a general population was to know the frequency, the potential risk factors, the morbidity, and social and economical impact of the urolithiasis in our subtropical Caribbean country. The prevalence was 4.64% and the annual incidence was 0.1%. Both are with in the estimated range of urolithiasis frequency in the world. It mainly started between 20 and 29 years in both genders. The white (5.2%) and the male (6.36%) patients were the most affected. 40% of all patients had a family history of urolithiasis. It was highly associated with diabetes mellitus, ischaemic cardiopathy, urinary tract infection and arterial hypertension. Stone formation was related to the warmer season. High calcium, protein-purine, carbohydrates and oxalic acid intake together with low fluid intake were closely associated with this disorder. 85% of patients had suffered renal colic and 75% of them more than once. Stone recurrence affected 33.8% of patients and 54.5% of them had more than one recurrence. Procedures for stone removal were needed in 33.8% of subjects. 40% of all patients were admitted to hospital due to urolithiasis morbidity. Non-specific medical treatment had been taken by 49.2% of the patients and specific treatment by none. Urolithiasis in this population was the some as has been reported in others studies. It has shown high frequency, increasing incidence, the same risks factors, high morbidity, and high social and economical impact. The low cost treatment is only taken by half of the patients.
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PMID:[Clinico-epidemiologic study of urolithiasis in a Caribbean urban area]. 1212 23


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