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Query: UMLS:C0018099 (gout)
 5,192 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Renal hemodynamics as measured by inulin clearance (Cinulin) and para-aminohippurate clearance (CPAH) was evaluated in 149 patients with primary gout over intervals of two to 22 years. In over 30 per cent of the patients plasma urate was greater than 10 mg/dl and urinary uric acid greater than 800 mg/min. A linear trend in decreasing frequency of hyperuricemia and excessive uricosuria is significantly related to the patient's age at the onset of gout. Group I consisted of 84 patients with uncomplicated gout in both clearance studies. Cinulin and CPAH were somewhat lower in patients larger than or equal to 50 years of age with longer duration of gout. Further reduction in clearances was minimal at the second clearance study in intervals of approximately 10 years. Group II included 27 patients who had no associated disease at the time of the first clearance study but in whom associated disease had developed by the time of the second clearance study. A striking reduction in Cinulin and CPAH was noted, especially in those 50 years old or above. There were 38 patients in group III with associated diseases at the time of both clearance studies. They had lower Cinulin and CPAH at the time of the first study, particularly the older patients. Further reduction during the second study was less striking than that in group II. Analyses of variance suggest that various coexisting vascular diseases with associated nephropathy have the most significant impact on the status of renal function in gout, with aging the second most important and duration of gout, the third.
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PMID:Renal function in gout. V. Factors influencing the renal hemodynamics. 50 87

The effect of ascorbic acid on the serum and urinary uric acid was studied in 14 subjects. Two to 6 h after the ingestion of 4.0 g of ascorbic acid, the fractional clearance of uric acid increased to 202% +/- 41% of the control value. This uricosuria was inhibited by pyrazinamide and by low-dose acetylsalicylic acid, but was not accompanied by an increase of the creatinine clearnace. Ascorbic acid did not diminish protein-bound uric acid. In 3 subjects who ingested 8.0 g of ascorbic acid for 3 to 7 days the serum uric acid decreased by 1.2 to 3.1 mg/dl as a result of a sustained uricosuria. These results suggest that ascorbic acid could invalidate studies involving the measurement of uric acid and obscure the diagnosis of gout in some cases. Theoretically it could precipitate attacks of gouty arthritis or renal calculi in predisposed persons. These observations show a pharmacologic effect of megadoses of a simple vitamin.
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PMID:Ascorbic acid-induced uricosuria. A consequency of megavitamin therapy. 125 82

The authors have established that to higher calciuria in patients with calcium nephrolithiasis correspond higher vales of uric acid serum concentrations and urine excretion than in the controls. In the oral calcium tolerance test a significant correlation was found between the changes in the uric acid urine excretion and those in the diuresis. The following conclusions are put forward. I. In the patients with recurrent calcium nephrolithiasis and hypercalcinosis one should look for active impairment of uric acid metabolism which should be kept in mind when an antirecurrence treatment is planned. 2. The established parallel increase of uricosuria and calciuria in the oral calcium tolerance test means that to patients with recurrent calcium nephrolithiasis and gout a rich calcium diet should not be prescribed since it increases the risk of formation of calcium oxalate stones.
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PMID:[The effect of oral calcium loading on the serum concentrations and urinary excretion of uric acid in patients with recurrent calcium nephrolithiasis and hypercalciuria]. 228 2

Metabolic studies were conducted in 56 patients with primary gout and in ten normal subjects to assess differences in the tubular transport mechanisms of urate. Renal handling of uric acid was examined by means of pyrazinamide and probenecid tests at increased and pharmacologically reduced serum urate concentrations in both groups. Patients with gout showed similar serum urate levels and glomerular filtration rates than controls at both serum urate levels. Pyrazinamide decreased urinary uric acid excretion to less than 1.0% of the urate filtered load in both groups at increased and diminished serum urate concentrations. The maximum uricosuric response promoted by probenecid at high serum urate levels was (mean +/- SD) 3,707 +/- 443 micrograms/min/1.73 m2 in controls and 2,215 +/- 738 micrograms/min/1.73 m2 in patients with gout (P less than 0.01). Forty-four patients had a daily uric acid excretion rate below 700 mg/1.73 m2, and all of them showed a diminished uricosuric response to probenecid. When serum urate was reduced in normal subjects and 30 patients to a mean of 2.1 and 2.3 mg/dL, respectively, probenecid elicited a significantly lower urate excretion rate in gout (532 +/- 202 micrograms/min/1.73 m2) than in controls (922 +/- 136 micrograms/min/1.73 m2; P less than 0.01). Among these 30 patients examined in their basal state and at decreased serum urate levels, uric acid excretion following probenecid was normal in six and diminished in 24 in both situations. The difference between maximum uricosuria and basal urate excretion was not increased in gouty patients.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Renal handling of uric acid in gout: impaired tubular transport of urate not dependent on serum urate levels. 378 14

The effect of various drugs on urate binding to plasma proteins was investigated in normal subjects. Whereas allopurinol, aspirin, phenylbutazone, probenecid, and sulphinpyrazone all significantly reduced plasma urate concentrations, only aspirin, phenylbutazone, and probenecid significantly impaired urate binding. Colchicine and indomethacin in the doses administered had no significant effect on plasma urate concentrations or binding. In the case of aspirin, urate binding was reduced to 25% of normal, and this effect was quickly abolished after cessation of therapy. Phenylbutazone reduced urate binding to 56% and probenecid to 46% of normal; this impairment was still detected four days after cessation of therapy. Drugs may impair urate binding by competition for plasma protein binding sites, with displacement of bound urate. Impairment of urate binding in vivo by administration of certain drugs may be relevant to the precipitation of acute gouty arthritis, to the formation of gouty tophi, and to the augmentation of uricosuria. Furthermore, the role of drugs must be seriously considered during all studies on urate binding in patients with gout.
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PMID:Effect of drugs on urate binding to plasma proteins. 535 47

In a metabolic ward study of five patients, azapropazone lowered plasma uric acid but exerted only a modest and variable uricosuric effect without altering urinary xanthine and hypoxanthine levels. An alternative mechanism other than uricosuria or xanthine oxidase inhibition must account for some of the hypouricaemic action of this drug. During the first day of treatment urine volume and pH declined sharply. In a separate investigation, 22 patients were given azapropazone and 18 were given allopurinol combined with colchicine for 3 months. Allopurinol reduced plasma uric acid more quickly but at the end of the study there was little difference in the hypouricaemic results achieved by both drugs. Recurrent gout occurred more frequently with allopurinol but side-effects were confined to those taking azapropazone. A slight rise in blood urea and creatinine and a fall in haemoglobin were also features of long-term azapropazone treatment.
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PMID:Azapropazone--a treatment for hyperuricaemia and gout? 669 72

To differentiate between extrarenal and renal causes of hyperuricaemia and gout, clearances of urate and creatinine were monitored for 3 1/2 days in fifty-two individuals (seven with a history of gout) with no gross impairment of renal function (creatinine clearance 52-137 ml/min). Dietary purine intake was kept constant. Monophasic circadian fluctuations of fractional urate excretion (= urate clearance over creatinine clearance) were observed with peak values in the afternoon, about 50% higher than during the night. Circadian fluctuations of urinary flow rate were almost identical. However, enhancement of urinary flow rate due to water diuresis had no effect on urate clearance. Despite wide variation of plasma urate concentrations among different individuals (+/- 30% SD), daily urate excretion varied little (+/- 4% SD) and did not correlate with plasma urate (r = 0.03). Thus extrarenal factors appear not to account for the occurrence of hyperuricaemia in these patients. In contrast, a clearcut negative correlation was apparent between plasma urate concentration and fractional urate clearance (r = 0.72), which could fully account for the variations of plasma urate concentration. To elucidate further the mechanism responsible for antiuricosuria in hyperuricaemic patients, the effects of the uricosuric agents benzbromarone and probenecid were tested. A clearcut correlation was apparent between control fractional urate excretion and uricosuric effect of both benzbromarone and probenecid (r = 0.83 and 0.88, respectively), suggesting that anti-uricosuria was due to defective secretion. In an additional series, the uricosuric effect of probenecid was tested in ten patients with renal insufficiency. In these patients the uricosuric effect was clearly blunted, indicating that urate reabsorption is reduced in renal insufficiency.
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PMID:Renal handling of urate in healthy man in hyperuricaemia and renal insufficiency: circadian fluctuation, effect of water diuresis and of uricosuric agents. 677 56

The uricosuric response to 80 mg of micronized Benzbromarone was employed to assess the renal tubular secretory site for uric acid in patients with primary gout. Since Benzbromarone selectively inhibits tubular reabsorption of secreted urate, the maximum uricosuria induced by this drug can be equated with the minimal secretory rate. Furthermore, a significant relationship was noted in normal controls between urate secretion and the plasma urate concentration (r = 0.956, p less than 0.005). Using the Benzbromarone response as a measure of tubular secretion, gouty patients with normal production hyperuricemia had a significantly lower secretory rate by comparison to patients with overproduction of uric acid. These data indicate that in patients with primary normal production hyperuricemia, the renal tubular defect is related to a decreased secretory response for a given plasma concentration of uric acid.
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PMID:Renal handling of uric acid in man. 706 39

Forty-nine patients with gout, many with hypertension and/or renal calculi, were given hydrochlorothiazide, furosemide, or ticrynafen. Diuresis and increased clearances of sodium (Na), potassium (K), chloride (Cl), and calcium (Ca) occurred after a single dose of hydrochlorothiazide, 100 mg, or furosemide, 40 mg, orally. There was very slight change in urate and phosphorus clearances. With prolonged use of hydrochloride or furosemide, diuresis and increased electrolyte excretion disappeared. Urate and Ca excretion fell with hydrochlorothiazide. With long-term use of furosemide, urate excretion was suppressed, but Ca excretion was sustained. Ticrynafen produced diuresis and increased clearances of Na, K, and Cl. Calcium excretion was increased after a single dose and minimally decreased after long-term use. Most striking was the severe and rather sustained uricosuria. Though ticrynafen is an effective uricosuric, natriuretic, and antihypertensive agent, its hepatotoxicity and nephrotoxicity mitigate against its clinical use.
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PMID:Effects of diuretics on urate and calcium excretion. 723 11

Introduction of new uricosuric diuretics will be accompanied by the unknown risk factors associated with the use of any new drug, as demonstrated by reports of hepatic toxicity associated with ticrynafen. In addition to unexpected reactions, there are potential risks related to induction of uricosuria, which are serious and have been reported to occur. More importantly, the risk of developing clinical gout or coronary heart disease due to mild asymptomatic hyperuricaemia appears minimal, so indications for the use of uricosuric diuretics are limited. If a uricosuric diuretic is thought necessary (and is available), it would seem prudent to measure the daily excretion rate of uric acid to identify those patients with hyperuricaemia related to overproduction of uric acid. A uricosuric diuretic should be avoided in those patients, as well as in patients with uric acid stones, and possibly in those with calcium stones. A uricosuric diuretic might be useful for patients with hypertension who also have hyperuricaemia due to a low excretion of uric acid.
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PMID:The risks of asymptomatic hyperuricaemia and the use of uricosuric diuretics. 726 49


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