Pathophysiology of Nonhypercalciuric Causes of Stones

Breslau, Neil A.; Sakhaee, Khashayar

doi:10.1007/978-1-4613-2069-2_3

Cited by 1 publication

(2 citation statements)

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“…The disorders frequently associated with uric acid stones are summarized in Table 1. Gouty population usually exhibits increased urinary excretion of uric acid which is further increased by high intake of purine-rich foods; 50% of patients with uric acid excretrion rate greater than 1000 mg/day form uric acid stones (1). High urine acidity greatly contributes to uric acid stone fo~mation in gouty patients.…”

Section: Uric Acid Nephrolithiasismentioning

confidence: 99%

“…As much as 50% of uric aCid derived from dietary purines may be recovered in the urine (2). One quarter of the uric acid produced daily IS excreted through Intestinal secretions undergoing uricolysIs by intestinal bacteria (3,4); a very small amount of the remaining three quarters is excreted through the skin (5), the nails (6), the saliva and the hair (1), While the remnant appears in the urine; in chroniC renal failure the extrarenal elimination is Increased as a compensatory phenomenon (…”

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confidence: 99%

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Uric Acid and Kidney

Fuiano

Federico

Conte

et al. 1989

Advances in Experimental Medicine and Biology

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Uric Acid MetabolismUric acid is the end product of purine metabolism in humans. In animals other than mammals uric aCid undergoes further degradation oecause of the activity of enzymes such as uricase, allantoinase and allantolcase; in some species the urea that is formed is further hydrolyzed to ammonia and C02 by the urease of intestinal bacteria (1).Uric acid derives from endogenous purines (normally at a constant rate) and from dietary purines. Variations in uric aCid production rate derives mainly from variations of dietary intake of purines (purine-rich foods Include poultry, meat. liver and fish). As much as 50% of uric aCid derived from dietary purines may be recovered in the urine (2). One quarter of the uric acid produced daily IS excreted through Intestinal secretions undergoing uricolysIs by intestinal bacteria (3, 4); a very small amount of the remaining three quarters is excreted through the skin (5), the nails (6), the saliva and the hair (1), While the remnant appears in the urine; in chroniC renal failure the extrarenal elimination is Increased as a compensatory phenomenon (1) • In the blood, at pH 7.4, uric acid is almost entirely as monovalent anion; since its protein binding is minimal, more than 95% of plasma urate IS freely filtered by glomeruli.About 90% of the filtered urate undergoes proximal tubular reabsorption: but after this reabsorption, uric aCid secretion at a similar rate (i.e. 90% of the filtered load) occurs, presumably in the proximal tubule. It has been demonstrated that a further postsecretory reabsorption takes place, which also approximates 90% of the filtered load and is believed to be the major determinant of final urinary excretion of uric acid which amounts to about 10% of the filtered urate.Factors that may influence urinary urate excretion are: plasma urate concentration, urine flow rate and effective blood volume. Thus, extracellular volume expansion by saline increases urate clearance causing hypouricemia; by contrast, volume contraction decreases urate clearance causing hyperuricemia (1).

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Section: Uric Acid Nephrolithiasismentioning

confidence: 99%

mentioning

confidence: 99%