Uric acid in plasma

In the absence of allopurinol, the dominant urinary purine is uric acid. During allopurinol treatment, the urinary purines include hypoxanthine, xanthine, and uric acid. Since each has its independent solubility, the concentration of uric acid in plasma is reduced and purine excretion increased, without exposing the urinary tract to an excessive load of uric acid. Despite their increased concentrations during allopurinol therapy, hypoxanthine and xanthine are efficiently excreted, and tissue deposition does not occur. There is a small risk of xanthine stones in patients with a very high urate load before allopurinol therapy this can be minimized by liberal fluid intake and urine alkalization. 

Immobilization of enzymes in the detector flow cell is of paramount importance in the performance of electrodes. The fabrication and performance of a reticulated vitreous carbon-based tyrosinase flowthrough electrode, in which the enzyme was covalently immobilized, was tested as an amperometric detector for phenolic compounds. The measurement of uric acid in plasma can be carried out through closed-loop FIA using a co-immobilized enzyme flow cell and chemiluminescence detection. 

In addition to ascorbic acid, uric acid is an important antioxidant in blood plasma (9). To assess the antioxidative capacity of plasma it is useful to determine ascorbic acid and uric acid in a single chromatographic run. Ascorbic acid and uric acid have been measured simultaneously from heparinized plasma by UV detection (64). To optimize the detection during method setup, the sample was dissolved in the mobile phase, pH 5.5, where ascorbic acid had the absorbance maximum at 262 nm and uric acid at 285 nm. The wavelength of 262 nm was chosen because ascorbic acid is present at a lower concentration than uric acid in plasma. The same mobile-phase pH (5.5) and UV detection at 280 nm for... 

MA Ross. Determination of ascorbic acid and uric acid in plasma by high-performance liquid chromatography. J Chromatogr 657 197-200, 1994. 

HPLC coupled to MS was used for the determination of dimethyl xanthine metabolites in plasma.82 There have also been a number of methods published on the use of HPLC with a PDA detector. In 1996, Mei published a method for the determination of adenosine, inosine, hypoxanthine, xanthine, and uric acid in microdialysis samples using microbore column HPLC with a PDA detector.63 In this method, samples were directly injected onto the HPLC without the need for any additional sample treatment. 

Modified procedure (ASC kit) Ascorbic acid is isolated from plasma proteins and uric acid in a single-step liquid gel chromatography procedure and its amount... 

When probenecid (ColBENEMID) is given in sufficient amounts, it will block the active reabsorption of uric acid in the proximal tubules following its glomerular filtration, thereby increasing the amount of urate eliminated. In contrast, low dosages of probenecid appear to compete preferentially with plasma uric acid for the proximal tubule anionic transport system and thereby block its access to this active secretory system. The uricosuric action of probenecid, however, is accounted for by the drug s ability to inhibit the active reabsorption of filtered urate. 

Uricosuric therapy should be initiated if several acute attacks of gouty arthritis have occurred, when evidence of tophi appears, or when plasma levels of uric acid in patients with gout are so high that tissue damage is almost inevitable. Therapy should not be started until 2-3 weeks after an acute attack. 

Duncan P, Gochman N, Cooper T, Smith E, Bayse D (1980) Development and evaluation of a candidate reference method for uric acid in serum or plasma. CDC, Atlanta, Ga. 

Some authors found a lower blood plasma TAC of women than men (by 23%) and a higher (by 21%) plasma TAC in persons having high serum cholesterol (>6 mM) (A12). The gender difference may be related to a lower concentration of uric acid in the blood serum of women (B7). 

Losartan appears to be unique among the ARBs because it inhibits the urate anion transport in renal proximal tubuli hence, it increases uric acid excretion and decreases plasma levels of uric acid in hypertensive patients. This effect is not the consequence of AT] receptor blockade. Since high uric acid levels have been associated with cardiovascular morbidity/mortality, losartan may be the best ARB for patients with gout [7,30,31]. Moreover, losartan was found to decrease ocular pressure in normotensive as well as in hypertensive patients [32]. 

Normal serum uric add is 0.025 to O.OSO mg/ml in males and 0,015 to 0,060 mg/ml in females. A uric add level greater than 0 070 mg/ml is associated with an increased risk for gout- Purine-restricted diets can result in plasma uric add le cls of 0.005 to 0.015 mg/ml. About two-thirds of the uric acid in the body is excreted via the urine the rest is excreted in the feces. Uric add accounts for only about 5% of urinary nitrogen. 

Various papers related to the simultaneous determination of creatinine and uric acid can be found in the hterature. Several authors have developed capillary zone electrophoresis (CZE) methods for simultaneous analysis of these compounds in urine. The CE analysis of these renal markers offers some advantages when compared with chromatography, such as shortened separation time, reduced reagent consumption, and increased resolution. Capillar micellar electrokinetic chromatography has been applied to the simultaneous separation of creatinine and uric acid in human plasma and urine. However, chromatographic techniques are widely accepted for the determination of these compounds. Reversed-phase and ion... 

Renal handling of uric acid is complex and involves four sequential steps (1) glomerular filtration of virtually aU the uric acid in capillary plasma entering the glomerulus (2) reabsorption in the proximal convoluted tubule of about... 

Nissen, P. Simultaneous determination of allopurinol, oxipurinol and uric acid in human plasma by high-performance Uquid chromatography. J.Chromatogr, 1982, 228, 382-386... 

Allopurinol also is useful in lowering the high plasma concentrations of uric acid in patients with Lesch-Nyhan syndrome and thereby prevents the complications resulting from hyperuricemia there is no evidence that it alters the progressive neurological and behavioral abnormalities that are characteristic of the disease. 

Table 5.5. Plasma concentrations of urea and uric acid in different species...

Mikaye, M., Shibukawa, A., and Nakasgawa, T. Simultaneous determination of creatinine and uric acid in human plasma and urine by micellar electrokinetic chromatography, J. HighResolut. Chromatogr., 14, 181, 1991. 

Allopurinol is a drug used primarily to treat hyperuricemia, which means excess uric acid in blood plasma and its complications, including chronic gout. It should be noted that allopurinol is not a uricosuric which means that it does not increase the excretion of uric acid in the urine so it can be used in patients with poor kidney function. Allopurinol has been marketed in the United States since 1966 under the trade name of Zyloprim. After it becomes... 

Human plasma contains a large population of proteins, with molecular weights ranging from 4,500,000-15,000,000. Plasma proteins are composed either exclusively of amino acids or of amino acids and lipids or carbohydrates. As already mentioned, plasma proteins may circulate independently or be conjugated to other plasma constituents, such as cholesterol or uric acid. Human plasma contains about 100 proteins, 40 of which are present in relatively large quantities and form 90% of the total plasma. The other 60 proteins constitute only 10%, and their function is frequently an enigma. Each of the second group of proteins is present in microquantities. 

In most patients with gout, the flow of plasma in the kidney, the glomerular filtration rate, and the renal clearance are normal, and no excess urates are found. Some investigators have claimed that gout is associated with abnormal tubular reabsorption of uric acid (93% in patients with gout versus 91% in normal individuals), leading to an absolute increase in total uric acid reabsorption and an accumulation of uric acid in the blood. 

C-uric acid in the plasma and urine samples was purified by polyacrylamide gel chromatography, as previously described (Bianchi et al., 1978 1979) P2 Biogel columns (Biorad Laboratories) were utilized to this purpose, with a 0.05 M phosphate elution buffer at pH 7. Fractions containing uric acid were pooled and counted in an automatic liquid scintillation counter. One ml samples were applied to each 0.9x28 cm column. 

THE EFFECT OF BEER INGESTION ON PLASMA AND URINE URIC ACID IN GOUT AND NORMOURICAEMIC SUBJECTS... 

The finding of hyperuricemia always means an increase of uric acid in the body In early and uncomplicated cases of gout, as well as in the normal, the plasma level of uric acid is proportional to the... 

---