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PubMed1975

[The significance of uric acid in calcium oxalate nephrolithiasis].

The findings of serum diagnosis (urea nitrogen, creatinine, uric acid, calcium, phosphorus) in 247 patients with oxalate stone were divided according to sex, and the excretion of uric acid, calcium and phosphorus was estimated. Compared with the control group, the levels of serum uric acid and serum calcium were statistically significantly raised, the mean level not exceeding the normal range. The serum uric acid level was 25% above the normal range in men and 20% above in women, and in the upper range of normal in one third of each, men and women. The excretion of uric acid in women exceeds the normal level in 32% of cases and in 40% of the men, sometimes considerably. The connection between pathological uric acid levels in the serum and urine and the development of oxalate stone, as well as the therapeutic consequences are discussed.

Adult↗
PubMed1991

Oleic acid-induced injuries in the guinea-pig. Effects of allopurinol on cell dynamics, erythrocyte-catalase and uric acid plasma levels.

1. Oleic acid was used to produce adult respiratory distress syndrome-like pulmonary microvascular injuries. The resulting injuries have previously indicated involvement of accumulating neutrophils (Hultkvist et al. 1988). Activated neutrophils release oxygen free radicals that may be possible to detect in the plasma. 2. The dynamics of neutrophils and platelets were studied in the guinea-pig after oleic acid-induced injury (0.03 ml/kg per 10 min). 3. As an indication of oxygen free radical activity, plasma levels of uric acid and red blood cell (RBC)-catalase, were analysed. 4. Allopurinol (10 mg/kg, i.p.) was given prior to oleic acid infusion to block the production of uric acid. 5. The neutropenia, in contrast to the thrombocytopenia seen at 15 min, was significantly inhibited in the allopurinol pretreated group compared with oleic acid and vehicle alone. 6. The blood plasma concentration of uric acid was significantly elevated after 15 min from start of experiment. Allopurinol pretreatment significantly reduced the uric acid plasma level. 7. The RBC catalase activity did not change with time within or between any groups. 8. The results indicate that sequestration of activated neutrophils in the microvasculature are to some extent oxygen free radical dependent.

Allopurinol↗
PubMed1978

Excretion of uric acid and amino acids during diuresis in the adult female Glossina morsitans.

Radiometric analysis was carried out on the urine collected for one hour following feeding of the adult female Glossina morsitans on day 1 of a pregnancy cycle, which had previously received haemocoelic injections of U-14C labelled arginine, histidine, leucine, lysine, phenylalanine, threonine, tyrosine or valine. Mean radioactivity in the urine was quite high after labelled arginine (17.4% of injected activity) and histidine (21.8%) administration, most of the activity being in the amino acid fractions. With the remaining six labelled amino acids, mean radioactivity in the urine varied between 1.6 and 7.2% of injected activity, most of this activity occurred in a non-amino acid fraction (probably uric acid), though low radioactivity was also detected in a range of essential as well as non-essential amino acids.

Amino Acids↗
PubMed1996

Normal serum uric acid concentrations in women with polycystic ovary syndrome.

Recently, an inverse correlation between serum uric acid concentrations and insulin sensitivity has been described in subjects with varying degrees of metabolic syndrome, suggesting that measurement of serum uric acid may provide a simple marker of insulin resistance. Several biochemical and clinical features of polycystic ovary syndrome (PCOS) resemble those of metabolic syndrome: women with PCOS are often obese; they are also at increased risk for the development of coronary artery disease, hypertension and diabetes mellitus. The objective of the present study was to analyse the usefulness of serum uric acid measurement in screening for the metabolic syndrome in women with PCOS. For that purpose serum concentrations of uric acid, insulin and triglycerides were measured in 38 women with PCOS and 20 weight-matched control women with regular menstrual cycles. No differences were found in the uric acid concentrations between the PCOS and control groups. The mean concentrations of triglycerides and fasting insulin were higher in the women with PCOS than in the healthy controls. Serum uric acid concentrations were inversely related to serum hormone-binding globulin (SHBG) concentrations, and positively with body mass index (BMI), insulin concentrations and testosterone:SHBG ratio in the PCOS group. Our results suggest that measurement of serum uric acid does not provide new means for identification of metabolic syndrome in patients with PCOS.

Adult↗
PubMed1975

Uric acid kinetic studies in the immediate post-myocardial-infarction period.

The etiology of hyperuricemia following myocardial infarction was investigated by uric acid kinetic studies carried out on seven male patients following myocardial infarction and on two control subjects. The patients selected had uncomplicated myocardial infarction and were maintained on a low-purine diet. Measurements of uric acid pool size and turnover rates using 2-C14 uric acid were made, commencing on days 2-5 following myocardial infarction. Initial concentration of serum uric acid ranged from 2.9 to 9.8 mg/100 ml. Uric acid pool size was elevated in six of seven patients. Five had a pool size of from 36.9 to 79.6 mg/kg, while the single gouty subject demonstrated 104 mg/kg compared with 12.6 and 16.8 mg/kg for the control subjects. Turnover rates were also increased, ranging from 1036 to 2772 mg/day (controls, 612 and 872 mg/day). Twenty-four-hour urine uric acid excretions ranged from 358 to 623 mg/24 hr. Serum lactic acid concentration was normal (1.03 plus or minus 0.17 muM/ml), and endogenous creatinine clearance in all cases was 77.9 ml/min or greater. These data suggest that following myocardial infarction there is an expansion of the uric acid pool with an increased uric acid turnover rate. Only the patient with a previous history of gout had uric acid excretion outside the normal range.

Body Weight↗
PubMed1976

Ultramicromethod for determination of plasma uric acid.

We describe an ultramicromethod for determination of uric acid by a manual procedure. Hydrogen peroxide, formed when uric acid is oxidized in the presence of uricase, oxidatively couples two molecules of p-hydroxyphenylacetic acid in the presence of peroxidase to produce a highly fluorescent compound. The specificity of the uricase reaction is retained, and the fluorometry results in a higher sensitivity (but a lower precision) than that obtained by applying spectrophotometric methods. As little as 50 ng of uric acid can be determined, and only 10 mul of plasma is required. Values obtained for human plasma are higher than those obtained by the spectrophotometric method.

Ascorbic Acid↗
PubMed1980

Effect of the organic matrix on the dissolution of uric acid stones.

Surface dissolution from a rotating disk of anhydrous uric acid crystals and a uric acid stone was determined at different pH levels and agitation intensities. The resistance of the organic matrix to the dissolution of uric acid from the stone was quantitatively measured. The significant effect of fluid motion on the matrix resistance is demonstrated.

Chemical Phenomena↗
PubMed1996

[Uric acid metabolism abnormalities in IgA nephropathies].

The possibility of uric acid tract stones forming was analysed in 12 children with IgA nephropathy (group I) and 10 children with other hematuric glomerulopathies (group II). Elevated serum uric acid level and higher urinary excretion was found only in children with IgAN during exacerbation of the disease. Uric acid nephrolithiasis was found only in children with IgA nephropathy. The prophylactic treatment (proper diet, high fluid intake, adjusting urinary pH to 6.5-6.8) was effective in decreasing the number of exacerbations, urinary tract infections and formation of uric acid stones.

Abdominal Pain↗
PubMed1985

[Diagnostic significance of determining the blood content of lactic and uric acids in chronic liver lesions of alcoholic and viral etiologies].

The concentration of lactic and uric acids in blood serum was measured in 115 patients with chronic liver lesions of virus (30 patients) and alcoholic (85 patients) etiology. The highest rise of lactic and uric acid concentrations was recorded in patients with alcoholic hepatitis and active alcoholic liver cirrhosis. The blood concentration of lactic and uric acids in alcoholic hepatopathy increased in parallel with an increment of the gravity of the pathological process, being the highest in patients with alcoholic hepatitis (lactic acid) and liver cirrhosis associated with the edematous ascites syndrome (uric acid). In inactive liver cirrhosis of alcoholic etiology, the concentrations of lactic and uric acids tended toward reduction, however, they were significantly higher than in the group of patients with virus liver lesions. Normal or negligible rises in the content of lactic and uric acids were seen in the groups of patients with chronic liver diseases of virus etiology. It is concluded that the measurement of the content of lactic and uric acids plays a diagnostic part in different patterns of alcoholic hepatopathies.

Adult↗
PubMed1978

Calcium-uric acid nephrolithiasis.

A small fraction of patients with nephrolithiasis form mixed stones containing calcium and uric acid or pass both calcium and uric acid stones; 23 of 539 patients we have studied fall in this category. These mixed stone formers tend to have unusually frequent stone recurrences. Although the patients are often considered to have a variant of uric acid nephrolithiasis, a high proportion harbor calcium as well as uric acid disorders. The usual treatment for uric acid lithiasis may fail to prevent calcium stone recurrence, unless concomitant calcium disorders are simultaneously corrected. Dual treatment may be very effective in preventing continued stone disease.

Adult↗
PubMed1998

The effect of menopause on serum uric acid levels in non-obese healthy women.

Elevated circulating serum uric acid concentrations may be linked with an increased risk of coronary heart disease (CHD). We measured serum uric acid levels in 50 premenopausal and 88 postmenopausal non-obese white women who underwent an intravenous glucose tolerance test. The uric acid concentration was significantly higher in postmenopausal versus premenopausal women. Adjustment of the data to take into account a number of confounding variables, including the age and body mass index (BMI), revealed a highly significant independent difference between the groups. BMI was found to be a significant independent predictor of the uric acid concentration, but this was confined to premenopausal women. Postmenopausal women were found to be more insulin-resistant, and significant correlations were observed between components of the insulin resistance syndrome and uric acid in both groups. We conclude that increases in serum acid in postmenopausal women may result from changes in metabolism as a consequence of the menopause, and may be associated with the increased risk of CHD seen in these women.

Adult↗
PubMed1985

The effect of pH and urine dilution on the electrophoretic mobility of uric acid crystals.

As a result of a continuing programme to understand better the uric acid stone treatment and prophylaxis, an investigation of the effect of pH and urine dilution on the surface charge of uric acid crystals was undertaken. A microelectrophoretic technique was employed to characterize the nature of the surface charge and the electrokinetics of uric acid crystals both in natural and synthetic urines under different conditions of pH and dilution. Both dilution and alkalization reduced the specific conductance of urine and increased the electrophoretic mobility (zeta potential) of uric acid crystals. The presence of cationic additives in diluted urine altered the zeta potential of uric acid crystals. Such findings suggest that proper control of the pH level and urine dilution as well as the surface charge at the solid-liquid interface represent an important factor in the uric acid stone prophylaxis.

Crystallization↗
PubMed2006

Effects of low birth weight in 8- to 13-year-old children: implications in endothelial function and uric acid levels.

Low birth weight has been associated with an increased incidence of adult cardiovascular disease. Endothelial dysfunction and high levels of serum uric acid are associated with hypertension. In this study, we have determined whether uric acid is related to blood pressure and vascular function in children with low birth weight. We evaluated vascular function using high-resolution ultrasound, blood pressure, and uric acid levels in 78 children (35 girls, 43 boys, aged 8 to 13 years). Increasing levels of uric acid and systolic blood pressure were observed in children with low birth weight. Birth weight was inversely associated with both systolic blood pressure and uric acid; on the other hand, uric acid levels were directly correlated with systolic blood pressure in children of the entire cohort. Low birth weight was associated with reduced flow-mediated dilation (r=0.427, P<0.001). Because the children with low birth weight had elevated uric acid as well as higher systolic blood pressure levels, we evaluated the correlation between these variables. In the low birth weight group, multiple regression analysis revealed that uric acid (beta=-2.886; SE=1.393; P=0.040) had a graded inverse relationship with flow-mediated dilation, which was not affected in a model adjusting for race and gender. We conclude that children with a history of low birth weight show impaired endothelial function and increased blood pressure and uric acid levels. These findings may be early expressions of vascular compromise, contributing to susceptibility to disease in adult life.

Adolescent↗
PubMed2006

Serum uric acid is a determinant of metabolic syndrome in a population-based study.

BACKGROUND: Determination of serum uric acid concentrations and role in risk of metabolic syndrome (MS) were investigated in 1877 participants in a cross-sectional population-based study including a brief follow-up. METHODS: The MS was identified by modified criteria of the Adult Treatment Panel III, and coronary heart disease (CHD) by clinical findings and Minnesota coding of resting electrocardiograms. Uric acid concentrations were measured by the uricase method. RESULTS: Metabolic syndrome was present in 39.1% of the cohort. Linear regression analysis of uric acid levels in a model comprising 13 variables identified gender, waist girth, total cholesterol (TC), alcohol usage, triglycerides, log C-reactive protein (CRP), and log gamma-glutamyl transferase (GGT), and in women diuretic use and elevated blood pressure (BP), as significant independent covariates whereby the largest contribution (1.6 mg/dL) was generated by waist girth. Logistic regression analysis of serum uric acid for MS disclosed for the top versus the bottom tertile an odds ratio (OR) of 1.89 (95% confidence interval [CI]: 1.45-2.46) in men and women combined, after adjustment for sex, age, TC, log CRP, log GGT, alcohol, and diuretic drug use, presence of diabetes/impaired fasting glucose, elevated BP, and smoking status. This corresponded to an increase by 35% in MS likelihood for each 1 SD uric acid increment. This rate declined to a significant 15% by inclusion of waist girth into the model. The OR of uric acid concentrations for prevalent and incident CHD, adjusted for age, MS, smoking, and diuretic use, was not significant among women and only tended toward significance in men. CONCLUSIONS: Abdominal obesity is the main determinant of uric acid variance. An increment of 1 SD in serum uric acid levels are associated in both sexes with a 35% higher MS likelihood, independent of 10 risk factors related to MS. After adjustment for waist girth, a more modest but significant likelihood persists, which suggests that serum uric acid is a determinant of MS.

Abdominal Fat↗
PubMed2005

Recurrent uric acid stones.

A 46-year-old female had a history of recurrent uric acid stone formation, but the reason why uric acid precipitated in her urine was not obvious, because the rate of urate excretion was not high, urine volume was not low, and the pH in her 24-h urine was not low enough. In his discussion of the case, Professor McCance provided new insights into the pathophysiology of uric acid stone formation. He illustrated that measuring the pH in a 24-h urine might obscure the fact that the urine pH was low enough to cause uric acid to precipitate during most of the day. Because he found a low rate of excretion of NH(4)(+) relative to that of sulphate anions, as well as a high rate of citrate excretion, he speculated that the low urine pH would be due to a more alkaline pH in proximal convoluted tubule cells. He went on to suspect that there was a problem in our understanding of the function of renal medullary NH(3) shunt pathway, and he suggested that its major function might be to ensure a urine pH close to 6.0 throughout the day, to minimize the likelihood of forming uric acid kidney stones.

Ammonia↗
PubMed1987

Serum and urinary uric acid in primary hyperparathyroidism.

Serum and 24-h urinary uric acid were measured in 29 patients with primary hyperparathyroidism pre- and post-operatively. No significant difference was observed. A positive correlation was found between the ratios of urinary calcium/creatinine and urinary uric acid/creatinine pre-operatively but not after surgery. The serum uric acid level showed an increase from the first to the third day post-operatively and returned to normal within a week, but in patients undergoing other urological operations there was no post-operative increase. On a low calcium diet the level of serum uric acid was found to be increased. These findings suggest that primary hyperparathyroidism has some influence on uric acid metabolism.

Adult↗
PubMed1957

Experimental uric acid nephritis in the rabbit.

Experimental uric acid lesions in the kidney of the rabbit have been reinvestigated using the technique of miscrodissection for location of lesions. The maximal initial lesion was found to occur in the first part of the collecting, and not in the ascending Henle and the distal convoluted tubule. Such lesions were only produced by very high dosage (approximately 0.5-1 gm. per kg.). It was concluded that the argument by analogy with the uric acid lesion cannot be used to support a hypothetical toxic damage to the segments of ascending Henle and the distal convolution in the crush syndrome.

Animals↗
PubMed2000

Influence of alkaline solutions on chemolitholysis and lithotripsy of uric acid stones. An in vitro study.

OBJECTIVES: This study was performed to look for an improvement of therapeutic strategies with regard to the treatment of uric acid stones using artificial stones made of uric acid (BON(N)-STONES) which are comparable to their natural counterparts. MATERIALS AND METHODS: Using an experimental arrangement simulating the physiological conditions in the upper urinary tract the efficacy of different alkaline solutions and artificial urine in dissolving artificial uric acid stones (BON(N)-STONES) was investigated. The dissolution of natural uric acid stones was measured and investigations on shock wave lithotripsy (SWL) combined with initial chemolytic treatment of the stones were performed. RESULTS: The efficacy of alkaline solutions, especially THAM at a pH of 10, in dissolving artificial uric acid stones was demonstrated. The investigations on SWL showed a significant improvement on stone comminution of artificial uric acid stones after initial chemolytic treatment with THAM. CONCLUSIONS: New basics to improve dissolution of uric acid stones have been developed by performing standardized in vitro investigations. The suggestion was confirmed that stone fragility and thus SWL can be improved by varying the physical properties of uric acid stones through initial treatment with THAM solution.

Lithotripsy↗