Improvement of the uric acid determination by the carbonate method for serum and urine

An improved colorimetric procedure for determining uric acid by the carbonate method in serum and urine is described, using a 20% sodium carbonate solution with urea. Reliable results are also obtained in high concentrations of uric acid.     

Micromethod for the determination of uric acid in biological fluids

A micro procedure for estimating uric acid in body fluids, based on the carbonate method, is described. Interferences are elucidated. The stoichiometry of the reaction is carefully worked out. Reliability of the method is established by comparison with two other methods, by recovery experiments, and by replicate analyses.     

Family resemblances in serum uric acid level

There is substantial relation between individuals' serum uric acid level and their heights and weights. Even when the association of uric acid level with height/weight is partialed out, significant resemblances in uric acid level are found between biologically related persons (parents and offspring; siblings) but not between spouses. When the association of height/weight is partialed out, uric acid level does not have a significant association with measures of cognitive ability or with educational or occupational attainment.The results reported here are made possible by a collaboration of a group of investigators (G. C. Ashton, R. C. Johnson, M. P. Mi, and M. N. Rashad at the University of Hawaii and J. C. DeFries, G. E. McClearn, S. G. Vandenberg, and J. R. Wilson at the University of Colorado) supported by NSF Grant GB-34720 and Grant HD-06669 from the National Institute of Child Health and Human Development.     

Theophylline increases serum uric acid levels

The present study was undertaken to investigate the effect of theophylline on serum uric acid and then to elucidate the mechanisms of action of theophylline as a cause of hyperuricemia. There was a significant increase of serum uric acid levels in male asthmatic patients who received theophylline compared to male control subjects without theophylline (6.3 +/- 0.4 mg/ml, mean +/- SEM, versus 4.3 +/- 0.2 mg/ml, p less than 0.01). A significant correlation of serum levels of uric acid and theophylline was demonstrated in asthmatic patients who received 200 to 400 mg sustained-release theophylline (male group, r = 0.480, p less than 0.001; female group, r = 0.398, p less than 0.01). Intravenous administration of aminophylline in three healthy adult male patients did not inhibit uric acid clearance, suggesting that inhibition of excretion of uric acid by theophylline is unlikely. Theophylline slightly inhibited hypoxanthine guanine phosphoribosyltransferase activity in human erythrocyte lysates at concentrations over 5 mM that is considerably more than therapeutic concentrations of theophylline as determined by the conversion of [14C]hypoxanthine to [14C]inosinic acid. Theophylline caused a moderate inhibition of [14C]hypoxanthine uptake by K-562 cells (approximately 50%) at 10mM that is over 100 times as high as those achieved clinically. Further studies remain to be performed to elucidate the exact mechanisms of theophylline-induced hyperuricemia.     

Automatic ultramicrotechnic for the determination of plasma uric acid]

An automatic micromethod is described for the estimation of plasma uric acid. The hydrogen peroxide formed when uric acid is oxidised by uricase, condenses by oxidation two molecules of p-hydroxyphenil-acetic acid in the presence of peroxidase. The product formed (dicarboxymethyl-5,5' dihydroxy-2,2' biphenyl) is fluorescent. This method permits one to estimate quantitites of uric acid of the order of 1 microng and permits measurement of uric acid in 50 microll of plasma. The values obtained for human plasma are compared to those supplied by a reductrimetric technique (SMA 12-60).     

Association of renal manifestations with serum uric acid in Korean adults with normal uric acid levels

Several studies have reported that hyperuricemia is associated with the development of hypertension and cardiovascular disease. Increasing evidences also suggest that hyperuricemia may have a pathogenic role in the progression of renal disease. Paradoxically, uric acid is also widely accepted to have antioxidant activity in experimental studies. We aimed to investigate the association between glomerular filtration rate (GFR) and uric acid in healthy individuals with a normal serum level of uric acid. We examined renal function determined by GFR and uric acid in 3,376 subjects (1,896 men; 1,480 women; aged 20-80 yr) who underwent medical examinations at Gangnam Severance Hospital from November 2006 to June 2007. Determinants for renal function and uric acid levels were also investigated. In both men and women, GFR was negatively correlated with systolic and diastolic blood pressures, fasting plasma glucose, total cholesterol, uric acid, log transformed C reactive protein, and log transformed triglycerides. In multivariate regression analysis, total uric acid was found to be an independent factor associated with estimated GFR in both men and women. This result suggests that uric acid appears to contribute to renal impairment in subjects with normal serum level of uric acid.