Uric Acid Stone Patients Research Articles

Potassium sodium hydrogen citrate intervention on gut microbiota and clinical features in uric acid stone patients

The high recurrence rate of renal uric acid stone (UAS) poses a significant challenge for urologists, and potassium sodium hydrogen citrate (PSHC) has been proven to be an effective oral dissolution drug. However, no studies have investigated the impact of PSHC on gut microbiota and its metabolites during stone dissolution therapy. We prospectively recruited 37 UAS patients and 40 healthy subjects, of which 12 patients completed a 3-month pharmacological intervention. Fasting vein blood was extracted and mid-stream urine was retained for biochemical testing. Fecal samples were collected for 16S ribosomal RNA (rRNA) gene sequencing and short chain fatty acids (SCFAs) content determination. UAS patients exhibited comorbidities such as obesity, hypertension, gout, and dyslipidemia. The richness and diversity of the gut microbiota were significantly decreased in UAS patients, Bacteroides and Fusobacterium were dominant genera while Subdoligranulum and Bifidobacterium were poorly enriched. After PSHC intervention, there was a significant reduction in stone size accompanied by decreased serum uric acid and increased urinary pH levels. The abundance of pathogenic bacterium Fusobacterium was significantly downregulated following the intervention, whereas there was an upregulation observed in SCFA-producing bacteria Lachnoclostridium and Parasutterella, leading to a significant elevation in butyric acid content. Functions related to fatty acid synthesis and amino acid metabolism within the microbiota showed upregulation following PSHC intervention. The correlation analysis revealed a positive association between stone pathogenic bacteria abundance and clinical factors for stone formation, while a negative correlation with SCFAs contents. Our preliminary study revealed that alterations in gut microbiota and metabolites were the crucial physiological adaptation to PSHC intervention. Targeted regulation of microbiota and SCFA holds promise for enhancing drug therapy efficacy and preventing stone recurrence.Key points• Bacteroides and Fusobacterium were identified as dominant genera for UAS patients• After PSHC intervention, Fusobacterium decreased and butyric acid content increased• The microbiota increased capacity for fatty acid synthesis after PSHC intervention

MP10-15 ALKALINE WATER: HELP OR HYPE FOR URIC ACID STONE PATIENTS?

You have accessJournal of UrologyCME1 Apr 2023MP10-15 ALKALINE WATER: HELP OR HYPE FOR URIC ACID STONE PATIENTS? Paul Piedras, Amanda McCormac, Seyed Amiryaghoub Lavasani, Minh-Chau Vu, Rohit Bhatt, Kalon Morgan, Andrei Cumpanas, Zachary Tano, John Asplin, Sohrab N. Ali, Pengbo Jiang, Jaime Landman, Ralph V. Clayman, and Roshan M. Patel Paul PiedrasPaul Piedras More articles by this author , Amanda McCormacAmanda McCormac More articles by this author , Seyed Amiryaghoub LavasaniSeyed Amiryaghoub Lavasani More articles by this author , Minh-Chau VuMinh-Chau Vu More articles by this author , Rohit BhattRohit Bhatt More articles by this author , Kalon MorganKalon Morgan More articles by this author , Andrei CumpanasAndrei Cumpanas More articles by this author , Zachary TanoZachary Tano More articles by this author , John AsplinJohn Asplin More articles by this author , Sohrab N. AliSohrab N. Ali More articles by this author , Pengbo JiangPengbo Jiang More articles by this author , Jaime LandmanJaime Landman More articles by this author , Ralph V. ClaymanRalph V. Clayman More articles by this author , and Roshan M. PatelRoshan M. Patel More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003225.15AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: The consumption of alkaline water, an electrolyzed mineral water with an average pH of 8-10, has been steadily increasing globally as proponents claim it to be a healthier alternative to tap water. Urinary alkalinization therapy is frequently prescribed in patients with uric acid nephrolithiasis but given low compliance there has been interest in alkaline water as a potential therapeutic alternative. For any fluid to have an alkalinizing effect on urine, it must contain organic anions such as citrate and bicarbonate. We analyzed five commercially available alkaline water products to assess their electrolyte and organic anion composition. METHODS: Five commercially available alkaline water brands (Essentia®, Smart Water® Alkaline, Great Value™ Hydrate Alkaline Water, Body Armor® SportWater, and Perfect Hydration®) were subjected to anion chromatography, acid titration, and direct chemical measurements to determine the mineral contents of each product. The alkali content of each brand of alkaline water was then contrasted with the alkali content of potassium citrate, sodium bicarbonate and other over the counter organic and synthetic beverages. RESULTS: The pH levels of the five alkaline waters ranged from 9.69-10.15; however, the electrolyte content was minimal, and the physiologic alkali content was <1 mEq (Table 1). The alkali content of all five brands of alkaline water was considerably lower than potassium citrate, sodium bicarbonate, and other common over the counter organic and synthetic beverages (Table 2). CONCLUSIONS: For uric acid stone patients, commercially available alkaline water has negligible alkali content and thus would likely provide no added benefit over consumption of an equal volume of tap water. Source of Funding: None © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e120 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Paul Piedras More articles by this author Amanda McCormac More articles by this author Seyed Amiryaghoub Lavasani More articles by this author Minh-Chau Vu More articles by this author Rohit Bhatt More articles by this author Kalon Morgan More articles by this author Andrei Cumpanas More articles by this author Zachary Tano More articles by this author John Asplin More articles by this author Sohrab N. Ali More articles by this author Pengbo Jiang More articles by this author Jaime Landman More articles by this author Ralph V. Clayman More articles by this author Roshan M. Patel More articles by this author Expand All Advertisement PDF downloadLoading ...

Urinary Risk Profile, Impact of Diet, and Risk of Calcium Oxalate Urolithiasis in Idiopathic Uric Acid Stone Disease.

The role of diet in the pathogenesis of uric acid (UA) nephrolithiasis is incompletely understood. This study investigated the effect of dietary intervention on the risk of UA stone formation under standardized conditions. Twenty patients with idiopathic UA stone disease were included in the study. Dietary intake and 24 h urinary parameters were collected on the usual diet of the patients and a standardized balanced mixed diet. Although urinary UA excretion did not change, the relative supersaturation of UA decreased significantly by 47% under the balanced diet primarily due to the significant increase in urine volume and pH. Urinary pH was below 5.8 in 85% of patients under the usual diet, and in 60% of patients under the balanced diet. The supersaturation of calcium oxalate declined significantly under the balanced diet due to the significant decrease in urinary calcium and oxalate excretion and the increase in urine volume. Dietary intervention is a key component in the management of UA nephrolithiasis. Urinary calcium and oxalate excretion should also be monitored in patients with pure UA calculi to reduce the risk of mixed stone formation with calcium oxalate. Lower urinary pH in UA stone patients can only be partially explained by diet.

Association of Gut Microbiota and Biochemical Features in a Chinese Population With Renal Uric Acid Stone.

Previous studies suggest that patients with nephrolithiasis exhibit dysbiosis in their gut microbiota, but those studies were conducted in calcium oxalate stone patients. We aimed to explore the association of gut microbiota and biochemical features of renal uric acid stone (UAS) patients in a Chinese population and identify the related bacteria that may affect the pathopoiesis of UAS. A case-control study of 117 patients with UAS, 123 patients with gout, and 135 healthy controls were included from January 2014 to October 2020. For each subject, data on demographics, biochemical parameters of blood and urine were analyzed. Fifteen patients with gout, 16 patients with UAS, 17 UAS patients with gout, and 17 healthy subjects were enrolled and provided fecal samples. The characteristics of gut microbiota were explored by using 16S ribosomal RNA (rRNA) gene sequencing and analyzed by using a combination of software mother and R. Hyperuricemia was the main risk factor for the development of gout and UAS. Obesity, dyslipidemia, and aciduria were unique risk factors for UAS patients. The richness, diversity, and relative abundance of dominant bacteria at the phylum and genus levels of gut microbiota in UAS patients were significantly distinct from other subjects. Abundance of Bacteroides and Fusobacterium was significantly positively correlated with the serum uric acid (UA) level of UAS patients. Fusobacteria was involved in the metabolism and degradation of certain short-chain fatty acids, amino acids, and sugars in pathopoiesis of UAS, and inhibited their synthesis pathways. Fusobacteria may be related to the pathogenesis of UAS, and this finding contributes to the personalized treatment of UAS from the perspective of maintaining micro-ecological equilibrium in gut.

Экскреция триптофана, лизина, триметиллизина, саркозина, холина и 4-пиридоксиновой кислоты с мочой при мочекаменной болезни

Introduction. The role of the organic matrix in urinary stones genesis in urolithiasis patients is still unclear. The presence of a large amount of protein in the urinary stones matrix suggests the participation of the protein matrix in lithogenesis. Research of the amino acids spectrum in urine is of great interest so far as amino acids are the part of the matrix proteins of the urinary stone. Material and methods. We analyzed urinary excretion of the following amino acids and low molecular weight compounds: tryptophan, lysine, trimethyllysine, sarcosine, choline and 4-pyridoxine acid. We used ultra-performance liquid chromatography in combination with a TQD mass spectrometer. Results. A higher level of excretion of choline and sarcosine is typical for patients with oxalate stones, compared with healthy people. Uric acid stone patients have high concentration of choline and extremely increased concentration of trimethyllysine in the urine unlike healthy individuals. Very low concentration of trimethyllysine, choline, sarcosine and higher excretion of tryptophan are specific for oxalate urolithiasis, in contrast to urate stone patients. Conclusion. The intensity of amino acids and low molecular weight compounds urinary excretion has characteristic features in patients with various types of urolithiasis and healthy individuals. Indicators of excretion of these amino acids and low molecular weight substances can serve as criteria for the activity of oxalate or urate lithogenesis along with the known metabolic lithogenic factors of urine. We can use it as additional target indicators to assess the success of anti-relapse treatment.

Aggregation of Nano- and Micro-Crystallites in Urine of Uric Acid Stone Formers and Healthy Controls

The aggregation of urine crystallites with different sizes in the urines of 5 cases of uric acid (UA) calculi patients and 5 cases of healthy controls were comparatively investigated by means of nanoparticle size analyzer. Different sizes of urine crystallites were obtained by filtrating the urine through microporous membrane with different pore sizes (0.22, 0.45, 1.2, 3, and 8 μm), respectively. The average particle size () increased rapidly with placement time (t) in the lithogenic patients. The values of the urine crystallites of the controls increased more slowly with t. When t was increased, the autocorrelation curves in the two types of urine crystallites became less smooth and the decay of the correlation curve became slower, and decay time of different sizes of urine crystallites both for the calculi patients and the controls increased. These results indicated that the urine crystallites of the controls were more stable than those of the patients. The rapid aggregation of urine crystallites may be an important factor affecting the growth of crystallites in UA stone patients.

2100 ASSOCIATION BETWEEN NEPHROLITHIASIS INCIDENCE AND NUTRITION, BASED ON DATA FROM JAPANESE NATIONAL SURVEYS

You have accessJournal of UrologyStone Disease: Evaluation & Medical Management (I)1 Apr 20132100 ASSOCIATION BETWEEN NEPHROLITHIASIS INCIDENCE AND NUTRITION, BASED ON DATA FROM JAPANESE NATIONAL SURVEYS Takahiro Yasui, Atsushi Okada, Li Zuo, Yasuhiko Hirose, Kazumi Taguchi, Takahiro Kobayashi, Masahito Hirose, Ryosuke Ando, Shoichi Sasaki, and Kenjiro Kohri Takahiro YasuiTakahiro Yasui Nagoya, Japan More articles by this author , Atsushi OkadaAtsushi Okada Nagoya, Japan More articles by this author , Li ZuoLi Zuo Nagoya, Japan More articles by this author , Yasuhiko HiroseYasuhiko Hirose Nagoya, Japan More articles by this author , Kazumi TaguchiKazumi Taguchi Nagoya, Japan More articles by this author , Takahiro KobayashiTakahiro Kobayashi Nagoya, Japan More articles by this author , Masahito HiroseMasahito Hirose Nagoya, Japan More articles by this author , Ryosuke AndoRyosuke Ando Nagoya, Japan More articles by this author , Shoichi SasakiShoichi Sasaki Nagoya, Japan More articles by this author , and Kenjiro KohriKenjiro Kohri Nagoya, Japan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2013.02.2009AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES To clarify the association between regional variations in nephrolithiasis incidence and nutrition intake, we evaluated data from Japanese national surveys. METHODS The incidences of nephrolithiasis in 12 regions of Japan were calculated on the basis of patient data, obtained in 2005, from 430 hospitals (n = 92,797). Nutrition intake data were extracted from the National Health and Nutrition Survey, conducted in each region by the Japanese Ministry of Health, Labour and Welfare. The association between the incidence of nephrolithiasis and the average intake of various types of food (cereals, potatoes, sugars, legumes, vegetables, fruits, seafood, meat, egg, etc.) or nutrients (proteins, lipids, carbohydrates, salt, potassium, calcium, vitamins, etc.) was examined according to the region; the association between stone composition and nutritional data was also examined. The association between the incidence rate of nephrolithiasis in each region were also analyzed relative to the nutritional intake. RESULTS Continuing surveys in Japan show fixed variations in the incidence of nephrolithiasis among geographic regions. The national average number of patients with nephrolithiasis was estimated to be 203.1 per 100,000 citizens. The intake of fruit was negatively correlated with the incidence of nephrolithiasis (r = -0.721, p = 0.008), whereas the intake of eggs (r = 0.537, p = 0.072) and sugar (r = 0.475, p = 0.119) tended to positively correlate with the incidence (Figure). The intake of potassium (r = -0.500, p = 0.098), vitamin K (r = -0.562, p = 0.057), and pantothenic acid (r = -0.560, p = 0.058) tended to negatively correlate with incidence. The proportion of uric acid stone patients, based on an infrared analysis of 8,877 upper urinary tract stones, was 4.5% for Japan. The intake of potatoes, vegetables, and confectionery was positively correlated with the content of calcium in stones (r = 0.676, p = 0.016; r = 0.614, p = 0.034; and r = 0.692, p = 0.013, respectively). CONCLUSIONS The incidence of nephrolithiasis is higher in geographic areas where the populations have low fruit and high sugar intake. These data are useful as a basis for investigating risk and nutritional factors associated with nephrolithiasis. © 2013 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 189Issue 4SApril 2013Page: e861 Advertisement Copyright & Permissions© 2013 by American Urological Association Education and Research, Inc.MetricsAuthor Information Takahiro Yasui Nagoya, Japan More articles by this author Atsushi Okada Nagoya, Japan More articles by this author Li Zuo Nagoya, Japan More articles by this author Yasuhiko Hirose Nagoya, Japan More articles by this author Kazumi Taguchi Nagoya, Japan More articles by this author Takahiro Kobayashi Nagoya, Japan More articles by this author Masahito Hirose Nagoya, Japan More articles by this author Ryosuke Ando Nagoya, Japan More articles by this author Shoichi Sasaki Nagoya, Japan More articles by this author Kenjiro Kohri Nagoya, Japan More articles by this author Expand All Advertisement Advertisement PDF DownloadLoading ...

Study on Nano- and Microcrystallites in Urines of Uric Acid Stone Patients

The presence of crystallites in urine is closely related to stones formation. In this article, the components, morphology of nano- and micro-crystallites in urines of 20 uric acid (UA) stone formers as well as their relationship with the formation of UAstones were comparatively studied using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The main constituent of urinary crystallites was uric acid. Their particle size distribution was highly uneven, ranging from several nanometers to several tens of micrometers, and obvious aggregation was observed. These results showed that there was close relationship among stone components, urinary crystallites composition and urine pH.

Calcium oxalate stone and gout

Gout is well known to be produced by increased uric acid level in blood. The objective of this paper is to assess the relationship between gout and calcium oxalate stone formation in the humans. 48 patients with combination of gout and calcium oxalate stone problem were included. The biochemical values of this group were compared with 38 randomly selected uric acid stone patients with gout, 43 stone patients with gout alone, 100 calcium oxalate stone patients without gout and 30 controls, making a total of 259 patients. Various biochemical parameters, namely serum calcium, phosphorus and uric acid and 24-h urine calcium, phosphorus, uric acid, oxalate, citrate and magnesium were analysed. ANOVA and Duncan's multiple-range tests were performed to assess statistical significance of the variations. The promoters of stone formation, namely serum calcium (P < 0.05), phosphorus (P < 0.05) and uric acid (P < 0.05) and urine calcium (P < 0.05), uric acid (P < 0.05) and oxalate (P < 0.05) were significantly variable in the different groups. The inhibitor citrate (P < 0.05) was also significantly variable. Multiple-range test showed that the promoters, namely serum calcium (P < 0.05) and urine uric acid (P < 0.05) were in a significantly higher range in the gouty patients, gouty uric acid stone patients and gouty calcium oxalate stone patients compared to the non-gouty patients and controls. Urine oxalate (P < 0.0001) was in the highest range in the gouty calcium oxalate or gouty uric acid stones patients. The inhibitor urine citrate (P < 0.001) was significantly lower in the gouty, gouty uric acid and gouty calcium oxalate patients. Serum uric acid was highest in the non-stone gouty patients, followed by the gouty uric acid stone formers and gouty calcium oxalate stone patients. The high values of promoters, namely uric acid and calcium in the gouty stone patients indicate the tendency for urinary stone formation in the gouty stone patients. There is probably a correlation between gout and calcium oxalate urinary stone. We presume this mechanism is achieved through the uric acid metabolism. The findings point to the summation effect of metabolic changes in development of stone disease.

Uric acid: an abettor or protector in calcium oxalate urolithiasis? Biochemical study in stone formers

Background Free radical induced renal damage leads to crystal retention and formation of large stones. However, the scenario behind uric acid (UA) stone formation is still a mystery, as uric acid, a risk factor of stone formation, seems to be a potent antioxidant that can protect cells from damage by reactive oxygen species. This study was intended to evaluate the role of uric acid in stone formers by assessing the oxidative stress status of the stone patients. Methods Determination of urinary stone forming risk factors and oxidative stress factors like plasma lipid peroxidation, protein carbonyls of stone formers and histopathological changes and uric acid deposition in stone patients kidney biopsy were studied. Results Increased concentrations of urinary uric acid and oxalate in both uric acid as well as calcium oxalate stone formers were observed, whereas calcium is increased in calcium stone formers and not in the uric acid stone patients. Inhibitors such as citrate and glycosaminoglycans (GAGs) were found to be significantly decreased in all the stone patients. Histopathological studies confirmed the deposition of crystals in the damaged tubules and De Galantha staining authenticates that the damage is caused due to uric acid crystals. Increased oxidative stress is dictated by the concentrations of lipid peroxidation and protein carbonyls in stone formers. Moreover, increased activities of urinary marker enzymes substantiate the tubular damage. Conclusion We speculated that uric acid acts as a calculi forming salt rather than an antioxidant and it has no role in preventing oxidative stress pertaining to urolithiasis.

The Role of the Diurnal Variation of Urinary ph in Determining Stone Compositions

The diurnal variation of urinary pH and urinary excretion of stone-forming constituents were investigated on 79stone patients. Composition of the stones was analyzed by means of infrared spectrophotometry. In uric acid stone patients urinary pH was low during the 24-hour period. In mixed calcium oxalate-calcium phosphate stone patients urinary pH was low in the early morning but high in the daytime and at night. In magnesium ammonium phosphate stone patients urinary pH was high throughout the entire day. On the other hand, urinary excretion of calcium was high in the mixed calcium oxalate-calcium phosphate stone patients and low in uric acid or magnesium ammonium phosphate stone patients. These findings suggested that the diurnal variation of urinary pH and urinary excretion of calcium might have an important role in determining stone composition.

Local chemolysis of obstructive uric acid stone with 0.1 M THAM and 0.02% chlorhexidine.

We used a modified chemolytic solution by combining 0.1 M THAM (tris[hydroxymethyl] aminomethane) with 0.02% chlorhexidine to treat 10 obstructive uric acid stone patients. A total of 23 local chemolysis sessions were performed. Five patients received 13 sessions (average: 2.6) as an adjuvant chemolysis after extracorporeal shock wave lithotripsy 5 patients received 10 sessions (average: 2) as a primary treatment. The average time of local chemolysis was 2.3 days, ranging from 1 to 4 days. In the 23 local chemolysis sessions, only one patient developed two episodes of fever (8.7%), which were managed successfully by conservative treatment. The mean values of effective renal plasma flow of treated kidney was increased from 108.2 to 155.6 ml/min (p < 0.05). The stone-free rate assessed by IVP and ultrasonography at 3 months follow-up was 80%. Our results indicate that the combined use of 0.1 M THAM and 0.02% chlorhexidine is an effective and safe method to treat obstructive uric acid stones.

Dietary Intake and Habits Of Japanese Renal Stone Patients

The daily consumption of various nutrients as well as the daily habits of 241 male stone patients were investigated. Hypercalciuric (300mg. or more per day) calcium stone patients ingested much more total protein, fats, oils and calcium than normocalciuric calcium stone patients, and uric acid stone patients ingested much more total and animal protein, and carbohydrates than calcium stone patients. However, the amount of ingested calcium by the patients (470mg.) was similar to that of age-matched healthy male subjects (476mg.) and did not reach the level of the daily nutritive requirements (600mg.). The patients ingested large amounts of nutrients, especially animal protein, during the evening meal. From these results it was believed that synthetic dietary management, including not only ingesting various amounts of nutrients but also changing dietary habits, is necessary for the prophylaxis of renal stones.

Uric acid lithiasis--a study of six hundred and twenty-two patients.

A clinical study is presented of 622 uric acid stone patients, constituting 34.6% of all patients with urolithiasis observed in a period of 12 years. The uric acid lithiasis in this series was essentially an upper urinary tract disease. Further evidence was obtained for idiopathic uric acid lithiasis being a disease entity, distinct from gouty uric acid lithiasis. Eighty percent of the uric acid stone patients were initially diagnosed as idiopathic uric acid lithiasis. Only 11 out of 359 patients with idiopathic uric acid lithiasis who came to follow up, developed gout. The majority of patients with idiopathic uric acid lithiasis were normouricemic and normouricosuric, only 13.6% of them became hyperuricemic during follow up. The male: female ratio in idiopathic uric acid lithiasis was 2.7:1, as compared with 12.3:1 in gouty uric acid lithiasis. In both the idiopathic and gouty uric acid lithiasis groups there was a preponderance of patients of European origin as compared with those of Near Eastern-Mediterranean origin. Myeloproliferative disease constituted a rare etiology in this series. There was a striking association of uric acid lithiasis with hyperparathyroidism, the latter occurring in 10.4% of the uric acid stone patients. Surgery and urinary tract infection was frequent.

Allopurinol in the prophylaxis of uric acid stones.

Rational prophylaxis of uric acid lithiasis comprises two principles: increase of uric acid solubility in the urine achieved by raising the urinary pH (Peters and Van Slyke, 1946; Prien, 1955; Sperling and de Vries, 1964), and decrease of urinary uric acid (UUA) concentration, achieved by raising urine volume and decrease of UUA excretion. Whereas a rise inurinarypH is easily attained by oral alkalinization therapy (Atsmon, -de Vries, and Frank, 1963; Kollwitz, 1964; Schmidt and Planz, 1965), two measures are available to decrease UUA concentration-high fluid intake and decrease in uric acid production, the latter having become recently feasible with the advent of the xanthine oxidase inhibitor, allopurinol (Wyngaarden, Rundles, Silberman, and Hunter, 1963). Satisfactory results have been reported in the literature in the prophylaxis of uric acid lithiasis by allopurinol in primary and secondary gout (Rundles, Silberman, Hitchings, and Elion, 1964; Yu and Gutman, 1964; Rundles, Metz, and Silberman, 1966b). In the present communication we wish to report on the treatment by allopurinol of non-gouty uric acid stone patients (Cases 1-7), and of one gouty patient with malignant uric acid lithiasis (Case 8). The therapeutic results of allopurinol administration in the seven non-gouty uric acid stone patients (one female and six males) are presented in Table I. The age at which the urolithiasis first manifested itself ranged from 20 to 57 years. All patients had passed innumerable pure uric acid stones and sand; only two (Cases 1 and 6) had in addition voided a few stones also containing calcium salts. Two patients (Cases 5 and 6) had periods of urinary tract infection. All seven patients had good kidney function during the whole period of follow up, their creatinine clearances at the start of allopurinol treatment ranging from'105 to 130 ml./min. Alkalinization combined with high fluid intake had been satisfactory for prolonged periods in all but Case 6, who, did not apparently, persistently adhere to the regime. Five patients did well on 300 to 600 mg. allopurinol for periods of 10 to 14 months, when repeat intravenous urography was normal in all. Allopurinol treatment had to be stopped early in Case 7 because of severe pruritus, and after 11 months in Case 6 because of leucopenia (total leucocyte count 2,200/mm.3); in both patients these sideeffects occurred after the dose had been raised to 600 mg. per day. In Case 6 x-ray evidence for a new stone was obtained after an attack of colic, 6 months after treatment with 300 mg. allopurinol per day. Relevant laboratory data obtained during allopurinol treatment are given in Table II (overleaf). In the period of alkalinization, ranging from 3 to 9 years, four patients showed hyperuricaemia (9 * 1, 7 * 7, 7 * 7, 7-1 mg./100 ml.)*, and three showed hyperuricosuria (1,140 to 1,600 mg./day). Interestingly, two of these hyperuricosuric patients (Cases 4 and 6) produced stones in the alkalinization period, but whether this stone formation was related to the hyperuricosuria cannot be decided, since both had also had at one time or another a very low urinary pH, presumably related to inadequate regime. During a short-lasting base-line period preceding allopurinol treatment, urinary pH reached low values in all patients and in all but one uric acid crystals appeared in the urine, in most in excessive amounts. Allopurinol decreased UUA excretion *We regard 3 to 6-4 mg./100 ml. as normal.