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PubMed2005

An evaluation of clinical accuracy of the EasyTouch blood uric acid self-monitoring system.

OBJECTIVES: Self-monitoring blood uric acid device is an important tool for patients to efficiently monitor their blood uric acid concentrations. The objective of the present study was to evaluate the accuracy of EasyTouch uric acid monitoring system. DESIGN AND METHODS: Capillary blood uric acid concentrations measured using EasyTouch and the reference values obtained from COBAS MIRA were performed in the Department of Laboratory Medicine, Wei-Gong Memorial Hospital. Results were evaluated using (1) linear regression analysis, (2) percentage of readings within a defined range of deviation from the reference value, and (3) coefficients of variation (CVs) calculated from 60 measurements in series. RESULTS: The window of the 177 EasyTouch readings covered a wide range from 0.1785 to 0.6367 mmol/L (3-10.7 mg/dL). Linear regression analysis yielded a regression slope of 0.975, an intercept of 0.0118 mmol/L and an R2 of 0.8966. Of the EasyTouch readings, 64 (36.2%), 61 (34.5%), 34 (19.2%), 9 (5.08%), and 9 (5.08%) were within the intervals of <5%, 5-10%, 10-15%, 15-17%, and >17%, respectively, of the reference values. Further analysis for the performance of each lot of strips showed that both coefficients of correlation and the percentages of readings within the CLIA's criterion (+/-17%), respectively, were in a narrow range from 0.8777 to 0.9541 and from 92.1% to 100%. The CVs for the seven lots of strips (lot 1 to lot 7) ranged from 2.93% to 6.33%, 3.2% to 5.9%, 3.64% to 7.0%, 2.84% to 7.6%, 2.68% to 5.42%, 3.03% to 6.93%, and 3.18% to 5.17%, respectively. CONCLUSION: EasyTouch is an acceptable diagnostic device which provides accurate uric acid measurements.

Adult↗
PubMedDate not supplied

Relation between serum uric acid and blood pressure in adolescents.

In adults, serum uric acid is positively associated with blood pressure levels. It is also a predictor of the development of hypertension in normotensive adults. The purpose of this study was to examine the relation of serum uric acid to systolic and diastolic blood pressure in adolescents. The data, from Cycle III of the National Health Examination Survey, consisted of a national probability sample of 6768 youths, 12-17 years old, in the United States. With age, height, weight, and sexual maturity controlled, serum uric acid significantly predicted blood pressure in adolescents. This relationship of uric acid and blood pressure was evident in male, but not female, adolescents. In association with findings from adult studies, these results indicate that uric acid levels may be useful indicators of adolescents at risk for hypertension.

Adolescent↗
PubMed1992

Circadian rhythm of plasma uric acid and handling stress-induced hyperuricemia in conscious cebus monkeys.

An apparent circadian rhythm of plasma uric acid and the effect of handling stress on plasma uric acid level in conscious cebus monkeys were demonstrated. The lowest level of plasma uric acid in the circadian rhythm occurred early in the morning and the highest, before bedtime at night. With experimental handling stress, the plasma uric acid level rose to much more than the maximum level of the circadian rhythm. Stress-induced hyperuricemia could be inhibited without an increase of urinary uric acid excretion by the minor tranquilizer diazepam at doses of more than 1 mg/kg, p.o. On the other hand, benzbromarone at 20 mg/kg, p.o. significantly inhibited the hyperuricemia with a hyperuricosuric effect, while probenecid at 50 mg/kg, p.o. had no effect on either the increased plasma uric acid or urinary uric acid excretion. Accordingly, it is concluded that the plasma uric acid level in conscious cebus monkeys easily fluctuates with experimental conditions and that the animals can be utilized to evaluate the hypouricemic and hyperuricosuric property of benzbromarone-like agents.

Animals↗
PubMed1988

Uric acid nephrolithiasis and acute renal failure secondary to streptozotocin nephrotoxicity.

Uric acid nephrolithiasis developed in a 75-year-old man who had received a large cumulative dose of streptozotocin for treatment of metastatic islet cell carcinoma of the pancreas. Oligoanuric renal failure mediated by massive intraureteral uric acid deposits occurred despite normal serum concentrations of uric acid. This case implicates the uricosuric effects of streptozotocin in the pathogenesis of uric acid nephropathy and suggests that renal uric acid excretion should be monitored routinely in patients receiving large cumulative doses of this drug.

Acute Kidney Injury↗
PubMedDate not supplied

Relationship of serum uric acid to cancer occurrence in a prospective male cohort.

Uric acid is a potent antioxidant and thus might protect against cancer. To test this hypothesis, we examined the relationship of serum uric acid to subsequent cancer incidence in a cohort of Japanese men in Hawaii. The study population consisted of 7889 men identified in the years 1965-1968 and followed by active hospital surveillance through November 1991. Cancer risk by serum uric acid level was analyzed using Cox proportional hazards regression with adjustment for age and, where indicated, smoking, alcohol use, and body mass index. No significant associations were seen for total cancer (1544 cases), or for cancers of the stomach (214), colon (272), rectum (105), lung (223), bladder (89), or hematopoietic system (77). For prostate cancer (293 cases), a positive association was found (relative risk for highest versus lowest quartile of serum uric acid = 1.5; 95% confidence interval 1.1-2.1; p for trend = 0.04). When the interval from examination to diagnosis was considered, this association was strongest for cases diagnosed in the first 10 years, was attenuated after 15 years, and disappeared completely after 20 years. The findings from this study do not support the hypothesis that uric acid protects against cancer occurrence.

Age Factors↗
PubMed1978

Uric acid excretion in normal children.

Standard values were established for urinary excretion and clearance of uric acid in 95 normal, nonhospitalized children. We found that urinary uric acid excretion and serum uric values increase throughout childhood; that in early childhood, fractional excretion and clearance of uric acid are higher than adult norms; and that despite an increasing filtered load of uric acid, there is a progressive decrease in fractional excretion and clearance of uric acid with advancing age. Some tubular maturational change, either decreasing secretion or increasing reabsorption, must account for the progressive decline in fractional excretion and clearance of uric acid.

Adolescent↗
PubMed2006

Simultaneous determination of ascorbic acid and dopamine in the presence of uric acid on ruthenium oxide modified electrode.

RuOx x nH2O film was electrochemically synthesized conveniently using cyclic voltammetric technique. The film formation was ascertained by the Electrochemical quartz crystal microbalance (EQCM) method and 45 ng of deposit per cycle was obtained. Stoichiometric ratio of the ruthenium and ruthenium oxide have been studied with different pH of phosphate buffer. The stability of the modified electrode in the presence of different cations and anions with different concentrations and pH were examined. Electrochemical studies have shown that the ascorbic acid (AA) and dopamine (DA) catalytic oxidation on ruthenium oxide modified electrode (RME) with a span of 300 mV separation even in the presence of uric acid (UA) with a large decrease in their respective over potential compared with bare glassy carbon electrode (GC). Accidentally, the reversible redox properties of the AA have been expediently studied on the RME using cyclic voltammetry and this peculiarity was interrogated through rotating ring disc electrode (RRDE) experiments. RRDE experiment results are conformed to the CV studies result and thus reversible redox property of AA have been reiterated. Amperometric detection under stirred condition up to approximately 0.8mM of AA and DA was carried out at free of electrode fouling. Interestingly, the regeneration of used RME electrode even after many consequent analysis, 100% was obtained.

Ascorbic Acid↗
PubMed2005

Uric acid renal excretion and renal insufficiency in decompensated severe heart failure.

OBJECTIVE: To evaluate uric acid renal excretion, hyperuricemia, renal dysfunction, and prognosis in patients with decompensated severe heart failure, as there are few data available. METHODS: One hundred and twenty-two patients, hospitalized for heart failure decompensation, in NYHA class IV, were classified into 3 groups as follows. Pilot group [ejection fraction (EF)</=0.45, n=16], group 1 (EF</=0.45, n=90), and group 2 (EF>0.45 and valvular dysfunction, n=16). The patients in groups 1 and 2 underwent assessment of creatinine and uric acid clearance before and after pyrazinamide, to estimate uric acid tubular secretion. Uric acid clearance <6.8 mL/min and secretion <170 microg/min were considered reduced. In groups 1 and pilot (n=106), mortality was analyzed by Cox regression model, and the prognostic value of hyperuricemia was assessed by ROC curve. RESULTS: In groups 1 and 2, respectively, serum uric acid was 511.7 and 422.5 micromol/L, and creatinine clearance was 46.7 and 61.4 mL/min. Uric acid clearance (3.2 vs. 3.9 mL/min) and tubular secretion (116 vs. 128 microg/min) were not different, but lower than normal values. In groups 1 and pilot, the 12-month mortality was 46.4% (CI 95%: 36.7%-56.0%). At end of follow-up, mortality was associated with impaired creatinine clearance (p<0.001), but not with hyperuricemia (p=0.236). CONCLUSIONS: In patients with decompensated severe heart failure, the tubular secretion and the clearance of uric acid were reduced. Renal dysfunction was associated with mortality, but hyperuricemia was not.

Female↗
PubMed1987

Action of uric acid, allopurinol and oxypurinol on the myeloperoxidase-derived oxidant hypochlorous acid.

Both oxypurinol and uric acid react with the myeloperoxidase-derived oxidant hypochlorous acid at physiological pH, and they can protect the elastase-inhibitory capacity of human alpha 1-antiprotease against inactivation by hypochlorous acid. Allopurinol does not protect alpha 1-antiprotease, possibly because the redox potential of allopurinol at physiological pH is too positive to permit oxidation by hypochlorous acid.

Allopurinol↗
PubMed2004

Novel insights into the pathogenesis of uric acid nephrolithiasis.

PURPOSE OF REVIEW: The factors involved in the pathogenesis of uric acid nephrolithiasis are well known. A low urinary pH is the most significant element in the generation of stones, with hyperuricosuria being a less common finding. The underlying mechanism(s) responsible for these disturbances remain poorly characterized. This review summarizes previous knowledge and highlights some recent developments in the pathophysiology of low urine pH and hyperuricosuria. RECENT FINDINGS: Epidemiological and metabolic studies have indicated an association between uric acid nephrolithiasis and insulin resistance. Some potential mechanisms include impaired ammoniagenesis caused by resistance to insulin action in the renal proximal tubule, or substrate competition by free fatty acids. The evaluation of a large Sicilian kindred recently revealed a putative genetic locus linked to uric acid stone disease. The identification of novel complementary DNA has provided an interesting insight into the renal handling of uric acid, including one genetic cause of renal uric acid wasting. SUMMARY: The recognition of metabolic, molecular, and genetic factors that influence urinary pH, and uric acid metabolism and excretion, will provide novel insights into the pathogenesis of uric acid stones, and open the way for new therapeutic strategies.

Circadian Rhythm↗
PubMed1996

Observations on serum uric acid levels and the risk of idiopathic Parkinson's disease.

Uric acid, an antioxidant found in high concentrations in serum and in the brain, has been hypothesized to protect against oxidative damage and cell death in Parkinson's disease. The authors tested this hypothesis among men participating in a 30-year prospective study known as the Honolulu Heart Program. Serum uric acid was measured in 7,968 men at the baseline examination held from 1965 to 1968. Of these men, 92 subsequently developed idiopathic Parkinson's disease (IPD). In analyses adjusted for age and smoking, men with uric acid concentrations above the median at enrollment had a 40% reduction in IPD incidence (rate ratio (RR) = 0.6; 95% confidence interval (CI) 0.4-1.0). Reduced IPD incidence rates persisted in analyses restricted to nonsmokers (RR = 0.5; 95% CI 0.3-1.0) and cases younger than age 75 years (RR = 0.5; 95% CI 0.3-0.9). Incidence rates were not notably affected when analyses were restricted to cases that occurred more than 5 years after uric acid measurement (RR = 0.6; 95% CI 0.4-1.0). Inclusion of known or computed correlates of uric acid in regression models did not substantially change risk of IPD. This study provides prospective evidence of an association between uric acid and reduced occurrence of IPD and indicates that further investigations of this association are warranted.

Aged↗
PubMed1997

[Determination of uric acid in scalp hair for non-invasive estimation of uricemic control in hyperuricemia].

Uric acid in blood has been widely accepted as a reliable indicator of hyperuricemia and gout, and its assay method has been established. In the present study, we developed a simple and non-invasive rapid method for the determination of uric acid in hair. Concentration(nmol/mg hair) of uric acid extracted from 10-20 mg of hair(95% < extractability; 0.1N KOH, 37 degrees C, 2 hr) was determined by an enzymatic method using uricase. The concentration of uric acid(nmol/mg hair, mean +/- SD: 0.489 +/- 0.157, n = 16) in hair from hyperuricemic patients was significantly higher than that(0.258 +/- 0.107, n = 8) from healthy volunteers(p < 0.01). Within-run and between-day precisions(reproducibilities, CVs) for the assay were 9.6-10.3%(n = 10 each) and 11.6-16.3%(n = 7 each), respectively. The concentration(y, nmol/mg hair) of uric acid in hair correlated well with that in blood(x, g/l): y = 8.770x-0.123(r = 0.746, Syx = 0.122, n = 23). Changes in the concentration of uric acid in hair of hyperuricemic patient treated with allopurinol paralleled to those in blood. In conclusion, it was confirmed that the concentration of uric acid in hair reflected that in blood, suggesting that measuring uric acid in hair can be available for the metabolic control in hyperuricemia.

Biomarkers↗
PubMed2003

Inhibition by uric acid of free radicals that damage biological molecules.

To clarify the antioxidative role of uric acid, its ability to scavenge carbon-centered and peroxyl radicals and its inhibitory effect on lipid peroxidation induced by various model systems were examined. Uric acid efficiently scavenged carbon-centered and peroxyl radicals derived from the hydrophilic free radical generator 2,2'-azobis-(2-amidinopropane)-dihydrochloride (AAPH). All damage to biological molecules, including protein, DNA and lipids induced by AAPH, was strongly prevented by uric acid. In contrast, alpha-tocopherol had little effect on damage to biological molecules. Lipid peroxidation by the lipophilic free radical generator 2,2'-azobis(2,4-dimethylvaleronitrile) (AMVN) was little inhibited by uric acid, but not by alpha-tocopherol. Copper-induced lipid peroxidation was inhibited by uric acid and alpha-tocopherol. NADPH- and ADP-Fe(3+)-dependent microsomal lipid peroxidation was efficiently inhibited by alpha-tocopherol, but not by uric acid. Uric acid seems to scavenge free radicals in hydrophilic conditions to inhibit lipid peroxidation on the lipid-aqueous boundary, and the antioxidation is only little in lipophilic conditions.

Amidines↗
PubMed1984

[Clinical value of the sequential study of the uric acid in CSF in patients with cerebral diseases: Part I. Brain tumor and the effect of irradiation].

Uric acid is the end product of the purine metabolism in the human and is mainly excreted to the urine. The studies on cerebrospinal fluid (CSF) uric acid in patients with various neurological diseases were reported in the literature. In the present study the authors discussed the clinical value of the sequential study of the CSF uric acid content in patients with brain tumors. CSF was investigated for uric acid in 23 controls and 30 cases of brain tumor. The results were as follows: The mean value and standard deviation of the uric acid in CSF in controls was 0.23 +/- 0.13 mg/dl. The uric acid in CSF increased in patients with malignant brain tumor (0.49 +/- 0.22 mg/dl, p less than 0.005), but was in normal range in patients with benign brain tumor (0.32 +/- 0.13 mg/dl, 0.10 less than p less than 0.25). There was no significant correlation between CSF uric acid and CSF protein contents. Uric acid in the lumbar CSF was approximately 4 times higher than in the ventricular CSF in patients with brain tumor. The CSF uric acid had progressively increased during irradiation to the whole brain. The factors contributing to increase of the uric acid in CSF were thought to be increased permeability of blood-CSF barrier, global damage of brain tissue, increased nucleic acid catabolism in the central nervous system (CNS) for example in tumor, inflammation or immunoreaction, increased of xanthine, hypoxanthine or xanthine oxidase activity in the CNS, directly increased of plasma components into the CSF due to such as subarachnoid hemorrhage, intraventricular hemorrhage, bleeding in the tumor or surgical operation, dysfunction of the CSF dynamics.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1979

Uric acid excretion: quantitative assessment from spot, midmorning serum and urine samples.

Uric acid excretion can be measured in milligrams of urinary uric acid per decilitre of glomerular filtrate by obtaining the product of urinary uric acid and serum creatinine concentrations and dividing by the urine creatinine (all concentrations in mg/dL). In 29 normal adult men, the excretion rate in spot, midmorning samples was 0.4 +/- 0.1 (SD) mg of uric acid per decilitre of glomerular filtrate. Eight of 36 untreated gouty men excreted acid at a rate more than three standard deviations above normal. Excretion of uric acid is conveniently and physiologically assessed by this simple method.

Gout↗
PubMed1978

Effect of feeding on plasma uric acid levels in snakes.

The effect of feeding on plasma-uric acid concentrations of the snake was studied. The values were monitored in 2 gopher snakes and 2 black rat snakes which were fed mice. Plasma uric acid values in snakes increased after eating and gradually returned to base line with the digestion of the mice. Uric acid concentrations were greater in snakes eating 2 mice than in those eating only 1 mouse. The base-line plasma uric acid concentration in snakes was approximately 2 to 5 mg/dl. Plasma uric acid concentrations may be useful in making a diagnosis of gout. Presence of gout is usually indicated by increased uric acid concentrations; however, interpretation of these concentrations should be based on information about the feeding schedule.

Animals↗
PubMed1986

Changes of uric acid level in rat brain after focal ischemia.

Changes of uric acid level in rat cerebral hemisphere after left middle cerebral artery (MCA) occlusion were studied by reversed-phase HPLC with electrochemical detection. Uric acid level in the normal group was 2.98 nmol/g tissue. Uric acid concentration of the left hemisphere in the left MCA-occluded group progressively increased after occlusion, and reached a maximum value of 67.26 nmol/g tissue 24 h after ischemia. Uric acid levels in the right hemisphere remained unchanged. Uric acid concentration of the left hemisphere in sham-operated group was 9.29 nmol/g tissue 24 h after the operation.

Animals↗