Xanthinuria in a familial group of Munchkin cats and an unrelated domestic shorthair cat.

CASE SERIES SUMMARY: Four confirmed cases of xanthinuria in cats, and one suspected case based on pedigree analysis, were identified. Clinical presentations varied and included haematuria, pollakiuria, dysuria, and urethral and ureteral obstruction. All cats had upper urinary tract uroliths. Diagnosis was obtained through infrared mass spectrometry of uroliths or urine. Clinical signs commenced at 3-8 months of age and reduced in all cats in the medium to long term after the introduction of a protein-restricted diet. Four cats were castrated males and one was a spayed female. Cases consisted of four Munchkin pedigree cats and one unrelated domestic shorthair cat. All four affected Munchkin pedigree cats were related, with three cases full siblings and the fourth case a half-sibling. No connection to the Munchkin pedigree could be established for the domestic shorthair cat. A candidate causative genetic variant (XDH p.A681V) proposed for this cat was excluded in the Munchkin family. RELEVANCE AND NOVEL INFORMATION: All affected cats presented diagnostic challenges and routine urinalysis was insufficient to obtain a diagnosis. Cases of feline xanthinuria may be underdiagnosed due to situations where uroliths cannot be retrieved for analysis and there is an inability to make a diagnosis using crystal morphology alone on routine urinalysis. Metabolic screening of urine may provide an effective mechanism to confirm xanthinuria in suspected cases where uroliths are inaccessible or absent. In this case series, male cats were more common. Their anatomy may increase the risk of lower urinary tract signs and urethral obstruction developing secondary to xanthine urolithiasis. A protein-restricted diet appears to reduce clinical signs as part of long-term management. PLAIN LANGUAGE SUMMARY: Four closely related Munchkin cats and one domestic shorthair cat were found with a suspected genetic disease causing high levels of xanthine in their urine. The case series looks at similarities and differences in their clinical signs, as well as difficulties experienced in obtaining a correct diagnosis. All cats had upper urinary tract stones and required metabolic testing of the stones or urine to diagnose. All cats were young when their clinical signs started and were on a high-protein diet. Four cats were desexed males and one was a desexed female. A genetic variant that may have caused the disease in the domestic shorthair cat was ruled out in the Munchkin family. Cases of high xanthine levels in feline urine may be underdiagnosed as the stones may not be accessed for testing. In this case series, male cats were more common. Their anatomy may increase the risk of lower urinary tract signs. A protein-restricted diet appears to reduce clinical signs as part of long-term management.

Metal ions-regulated chemical vapor generation of Hg2+:mechanism and application in miniaturized point discharge atomic emission spectrometry assay of oxalate in clinical urolithiasis samples.

It is well known that the coexisting metal ions could significantly influence the atomic spectroscopy (AS) analysis. In this work, a cation-modulated mercury ions (Hg2+) strategy via chemical vapor generation (CVG) was developed for oxalate assay due to the phenomenon that the Ag + can significantly reduce the Hg2+ signal. The regulation effect was studied in depth via experimental investigations. Since Ag + can be reduced to silver nanoparticles (Ag NPs) by reductant SnCl2, the decrease of the Hg2+ signal is attributed to the formation of a silver-mercury (Ag-Hg) amalgam. Due to the oxalate can react with Ag + to generate Ag2C2O4, which can reduce the generation of Ag-Hg amalgam, a portable and low-power point discharge chemical vapor generation atomic emission spectrometry (PD-CVG-AES) system was constructed to quantify the content of oxalate via monitoring the signal of Hg2+. Under optimal conditions, the limit of detection (LOD) was as low as 40 nM in the range of 0.1-10 µM for oxalate assay, while exhibiting good specificity. This method was applied to quantitative oxalate in 50 clinical urine samples of urinary stones patients. The levels of oxalate detected in clinical samples were consistent with clinical imaging results, which is promising for point-of-care testing in clinical diagnosis.

Mineralogy, geochemistry, and micromorphology of human kidney stones (urolithiasis) from Mersin, the southern Turkey.

This study describes the primary characteristics of the selected kidney stones surgically removed from the patients at the Mersin University Hospital in the southern Turkey and interprets their formation via petrographic, geochemical, XRD, SEM-EDX, and ICP-MS/OES analyses. The analytical results revealed that the kidney stones are composed of the minerals whewellite, struvite, hydroxyapatite, and uric acid alone or in different combinations. The samples occur in staghorn, bean-shaped composite, and individual rounded particle shapes, which are controlled by the shape of the nucleus and the site of stone formation. The cross-section of the samples shows concentric growth layers due to variations in saturation, characterizing the metastable phase. Kidney stone formation includes two main stages: (i) nucleation and (ii) aggregation and/or growth. Nucleation was either Randall plaque of hydroxyapatite in tissue on the surface of the papilla or a coating of whewellite on the plaque, or crystallization as free particles in the urine. Subsequently, aggregation or growth occurs by precipitation of stone-forming materials around the plaque or coating carried into the urine, or around the nucleus formed in situ in the urine. Urinary supersaturation is the main driving force of crystallization processes; and is controlled by many factors including bacterially induced supersaturation.

Diet, Fluid Intake, Urine Output and Urinary Sodium/Potassium Ratios in Children With Urolithiasis.

We performed a cross-sectional study on 25 children (17 boys) with urolithiasis with normal glomerular functions at a tertiary care teaching hospital between March, 2018 to March, 2019. Dietary assessment showed that caloric intake was below recommended dietary allowance (RDA) in 68% patients while the median protein intake was 34.3% more. The fluid intake was below the recommended standards in 56%, and 48% of the children had urine output below 1.5 mL/kg/hour. The urinary sodium was elevated in 96% of the children, urinary potassium was low in 40%, and hypercalciuria was seen in 28%. While metabolic causes predominate in childhood urolithiasis, other factors like dietary changes, liberal fluid and low sodium intake are advised for prevention of recurrences as they have a contributory role too.

Observation and identification of autofluorescent urine crystals may be linked to a sign of urolithiasis.

Urolithiasis is a common disease of the urinary system. Its recurrence rate is high and may increase medical expenses. Urine stones are composed of urine crystals and other impurities. We discovered the existence of autofluorescence in some of the urine crystals, especially in urolithiasis patients. The fluorescent molecule existed in urine crystals was verified and identified. We have applied micro-Raman and fluorescence microscopy to classify the urine crystals, used confocal laser scanning microscopy (CLSM) to examine the 3D images and spectra of autofluorescence in crystals, used Fourier-transform infrared spectroscopy (FTIR) and mass spectrometry (MS) to identify the type of fluorophore in the autofluorescent urine crystals in urine. Riboflavin was identified as one of the major fluorophores in these autofluorescent urine crystals. The prevalence rates of the autofluorescent crystals in urolithiasis patients and subjects without the history of urolithiasis were to gather statistics. We observed that 80% of urolithiasis patients had autofluorescent crystals. Contrastingly, such crystals existed in only 7% of subjects without the history of urolithiasis. The presence of autofluorescent urine crystals may be linked to a sign of urolithiasis.

Investigation of the potential anti-urolithiatic activity of Alhagi maurorum (Boiss.) grown wild in Al-Ahsa (Eastern Province), Saudi Arabia.

The potential of Alhagi maurorum (Boiss.) aqueous extract (AME), used in traditional medicine for treatment or prevention of urolithiasis, to dissolve calcium oxalate stones in vitro was evaluated. In order to determine the litholytic potential of the extract, Calcium oxalate urinary stones were incubated during 12 weeks under continuous shaking in the presence of AME, Rowanix or NaCl 9 g/mL solution were used as controls. After the incubation period, the residual weight of the treated calculi was determined and the rate of dissolution was calculated. The medium pH variation was measured and changes in the calcium oxalate crystals at the stone surface were assessed using a scanning electron microscope (SEM). The results showed a significant dissolution effect for the extract on the kidney calculi during the experimentation period. At the end of the experiment, the percentages of calculi weight decrease were 41.23, 4.97 and 55.67% for the extract, NaCl solution and Rowanix, respectively. Gas Chromatography analysis revealed mainly the presence of the following phyto-compounds: Cyclopropenone, 2,3-diphenyl; 1-Nonadecanol; methyl-alpha-D-mannopyranoside; cis-9-Hexadecenal. These compounds unarguably play crucial roles in the health care system especially in cancer treatment and many other diseases including urolithiasis. The urinary stone dissolution, independent of medium pH, could be attributed to formation of complexes between the phytochemical compounds in the extract and the calculi.

Acidification of 24-hour urine in urolithiasis risk testing: An obsolete relic?

BACKGROUND: Recommendations on the optimal preservation of 24 h urine for the metabolic work-up in urolithiasis patients are very heterogeneous. In case two such tests with different storage condition recommendations are being analysed, multiple collections would be needed, challenging especially elderly and very young patients. We therefore aimed to evaluate the stability of urine constituents under different storage conditions. MATERIAL AND METHODS: We collected urine samples from ten healthy volunteers and prepared aliquots to be stored either at room temperature or 4 °C. Some aliquots were preserved using hydrochloric acid prior to storage, some thereafter, some using the BD Urine preservation tube and some were not preserved at all. Storage duration was 0, 24, 48 or 72 h. In all samples calcium, magnesium, phosphorus, creatinine, oxalate, citrate and uric acid were measured and compared to the according reference sample. RESULTS: We could not find any significant deviation for any of the analytes and preanalytical treatment conditions compared to the associated reference sample. CONCLUSION: Preservation of 24 h urine for the metabolic evaluation in stone formers might not be necessary for sample storage up to 72 h.

Comparative functional analysis of the urinary tract microbiome for individuals with or without calcium oxalate calculi.

Individuals with urinary stone disease (USD) exhibit dysbiosis in the urinary tract and the loss of Lactobacillus that promote urinary tract health. However, the microbial metabolic functions that differentiate individuals with USD from healthy individuals are unknown. The objective of the current study was to determine the microbial functions across prokaryotic, viral, fungal, and protozoan domains that are associated with calcium oxalate (CaOx) stone formers through comparative shotgun metagenomics of midstream, voided urine samples for a small number of patients (n = 5 CaOx stone formers, n = 5 healthy controls). Results revealed that CaOx stone formers had reduced levels of genes associated with oxalate metabolism, as well as transmembrane transport, proteolysis, and oxidation-reduction processes. From 17 draft genomes extracted from the data and > 42,000 full length reference genomes, genes enriched in the Control group mapped overwhelming to Lactobacillus crispatus and those associated with CaOx mapped to Pseudomonas aeruginosa and Burkholderia sp. The microbial functions that differentiated the clinical cohorts are associated with known mechanisms of stone formation. While the prokaryotes most differentiated the CaOx and Control groups, a diverse, trans-domain microbiome was apparent. While our sample numbers were small, results corroborate previous studies and suggest specific microbial metabolic pathways in the urinary tract that modulate stone formation. Future studies that target these metabolic pathways as well as the influence of viruses, fungi, and protozoa on urinary tract physiology is warranted.

Three-channel ion chromatograph for improved metabolic evaluation of urolithiasis.

BACKGROUND: Urolithiasis is a multi-etiological disease resulting from a combination of environmental and genetic factors. One of the most challenging aspects of this disease is its high recurrence rate. For most patients, an in-depth metabolic evaluation may reveal the presence of urinary stones. The fact that different urinary stone-related compounds (USRCs) are measured by different methods renders the metabolic evaluation of urolithiasis quite tedious and complex. METHODS: A three-channel ion chromatograph (IC) that automatically measures the concentration of common metabolic indicators of urolithiasis in urine (i.e., oxalate, citrate, uric acid, calcium, and magnesium) was developed to improve the efficiency. To validate its precision and specificity, standard curves were prepared using working solution of these indicators. 100 standard solutions of these indicators were measured with our new IC and three other ICs as the control instruments; analyte concentrations in 100 24-h urine samples from volunteers and 135 calculi patients were also measured. RESULTS: All analytes had good linear relationships in concentration ranges of 0-10 mg/L. The precision experiments in the standard and urine samples showed that the measurement errors of the newly developed IC were all less than 5%. In urine, the recovery rate ranged from 99.6 to 100.4%, the coefficient of variation ranged from 1.39 to 2.99%, and the results matched between our newly developed IC and the control ICs. The results of the efficiency test showed that we can finish the analysis at the average number of 14 people per day with the new IC. While the average number in the control group is 3.85/day (p = 0.000). CONCLUSIONS: Overall, this multi-channel system significantly improves the efficiency of metabolic evaluation while retaining accuracy and precision.

Age-Specific Excretion of Calcium, Oxalate, Citrate, and Glycosaminoglycans and Their Ratios in Healthy Children and Children with Urolithiasis.

We analyzed children with urolithiasis with age- and gender-matched healthy children. Calcium (mmol/mmol creatinine) and the calcium/citrate ratio (mol/mmol) are the only variables that differentiate children before puberty from healthy children (ROC analysis confirmed only calcium/citrate as a significant variable with cut-off value > 0.84). Peri-pubertal children are distinguished from age- and gender-matched healthy children by the following variables: citrate (mmol/mol creatinine), calcium/citrate (mol/mmol), oxalate/glycosaminoglycans (mmol/g), oxalate/citrate ratios (mmol/mmol) and oxalate/(citrate × glycosaminoglycans) (mol oxalate × mol creatinine)/(mol citrate × g glycosaminoglycans). All variables were confirmed by ROC analysis with cut-off values ≤ 327.87, >1.02, >11.24, >0.12 and >0.03, respectively. These results indicate a different risk of urinary stones development before puberty vs. pubertal/postpubertal children and increasing importance (deficiency) of citrate and glycosaminoglycans in such children. J48 classifier confirmed the importance of the oxalate/(citrate × glycosaminoglycans) and the calcium/citrate ratios (Ox/Cit × GAG 0.22 and Cit/GAG 0.612) with the practically applicable classification tree for distinguishing between pubertal/postpubertal children with urolithiasis with age- and gender-matched healthy children.

Fructose-Rich Diet Is a Risk Factor for Metabolic Syndrome, Proximal Tubule Injury and Urolithiasis in Rats.

Excessive consumption of fructose (FR) leads to obesity, metabolic syndrome (MS) and insulin resistance, which are known risk factors for kidney stones. The epidemiological study has suggested the association between fructose consumption and urolithiasis, but the precise mechanism is still not well understood. Male Wistar rats were assigned for 8 weeks to three groups with different FR content in diet: RD (n = 5)-regular diet with a FR < 3%; F10 (n = 6)-regular diet with an addition of 10% Fr in drinking water; F60 (n = 5)-60% FR as a solid food. Serum concentration of FR, creatinine (Cr), insulin (Ins), triglycerides (Tg), homocysteine (HCS), uric acid (UA), calcium (Ca), phosphate (Pi), magnesium (Mg) and sodium (Na) were measured. Based on 24 h urine collection the following tests were performed: urine pH, proteinuria (PCR), excretion of N-Acetyl-(D)-Glucosaminidase (NAG), monocyte chemoattractant protein (MCP-1), uric acid (uUAEx), phosphate (uPiEx), calcium (uCaEx), magnesium (uMgEx) and sodium (uNaEx). The creatinine clearance (CrCl) was calculated. Calcium deposits in kidney sections were examined using hematoxylin and eosin (HE) and von Kossa stains. The rats on F10 and F60, as compared to the RD diet, showed a tendency for lower CrCl, higher HCS level and some features of MS as higher Ins and TG levels. Interestingly, F10 (fluid) versus F60 (solid) diet led to higher serum Ins levels. F10 and F60 versus RD demonstrated higher urinary excretion of MCP-1 and NAG which were suggestive for inflammatory injury of the proximal tubule. F10 and F60 as compared to RD showed significantly lower uUAEx, although there were no differences in clearance and fractional excretion of UA. F60 versus RD induced severe phosphaturia (>30×) and natriuria (4×) and mild calciuria. F10 versus RD induced calciuria (3×), phosphaturia (2×) and mild natriuria. Calcium phosphate stones within the tubules and interstitium were found only in rats on FR diet, respectively, in two rats from the F10 group and another two in the F60 group. The rats which developed stones were characterized by significantly higher serum insulin concentration and urinary excretion of calcium and magnesium. A fructose-rich diet may promote development of calcium stones due to proximal tubule injury and metabolic syndrome.

[Bacteriological correlation of urinary stones and preoperative urine culture: Is there a significant impact on postoperative infectious risk? (Moroccan experience)]. / Corrélation bactériologique entre les calculs urinaires et l'ECBU préopératoire : a-t-il un impact sur le risque infectieux postopératoire ? (expérience marocaine).

AIM: The objectives of this study were to evaluate the impact of preoperative urine culture and the infected nature of stones on the occurrence of postoperative urinary sepsis. MATERIAL AND METHODS: A prospective monocentric study included 29 patients operated on for urolithiasis between January and June 2018. RESULTS: Postoperative urinary sepsis was observed in 4 patients (14%). Urinary colonization rate on preoperative CBU exam was 27.6% (8 of 29) while the rate of colonized stones was 31% (9 of 29). The occurrence of urinary sepsis was observed in 37.5% (3 of 8) of patients with urinary colonization, compared to 44.4% of patients with colonized stones (4 of 9). By comparing the bacteriological results observed during sepsis, the germs isolated in postoperative urine were the same found in the culture of stones. The chemical nature of the colonized stones was mainly calcium oxalate (monohydrate, dihydrate) P=0.02. There was a statistically significant correlation between the preoperative urine culture, the bacteriological culture of stones and the postoperative urinary sepsis (P=0.05, P=0.005) respectively. CONCLUSION: Our study demonstrated a strong association between the bacteriological culture of stones and postoperative urinary sepsis superior to preoperative urine culture. It makes it possible to anticipate the occurrence of sepsis in patients requiring many endoscopic treatments. However, several multicentric prospective series may prove necessary to validate these results. LEVEL OF EVIDENCE: 3.

Characteristics of the genotype and phenotype in Chinese primary hyperoxaluria type 1 populations.

The aim of our study is to explore the relationship between genotype and phenotype in Chinese PH1 patients and determine the putative mutation hotspot regions. This was a retrospective study regarding 13 Chinese PH1 patients. And all sporadic published researches of Chinese PH1 populations were searched and enrolled based on the inclusive standard. All patients presented with multiple urolithiasis or nephrolithiasis. Urinary oxalate values demonstrated an obvious and extensive variability, ranging from 1.01 to 3.85 mmol/1.73 m2. Molecular diagnosis showed that 13 mutant types were detected. Infantile form patient (pt.) 10 and five patients (pts. 5, 7, 8, 9, 12) carrying c.815_816insGA or c.33_34insC demonstrated a worse prognosis, of whom pt. 5 progressed into ESRD 4 years later and died of chronic kidney failure. Based on the integrated Chinese mutation data, two variants (c.815_816insGA and c.33_34insC) were determined as the most common mutations. Besides, c.1049G>A was initially identified in a Chinese patient. Conclusions: heterogeneity between genotype and phenotype was observed and described in Chinese PH1 patients. c.815_816insGA and c.33_34insC which were recognized as AGXT mutation hotspot regions in China implied a poor prognosis. And c.1049G>A was not determined as the race-specific mutation of Pakistani.

Urolithiasis in complicated inflammatory bowel disease: a comprehensive analysis of urine profile and stone composition.

PURPOSE: To evaluate the impact of extensive surgery on urine profile, serum exams and stone composition of complicated IBD patients. METHODS: Patients with IBD and a history of total proctocolectomy (TPC) with fecal diversion (end ileostomy or ileal pouch anal anastomosis-IPAA) were selected. Only patients with at least one complete 24-h urine profile were included. A case-control study was performed selecting patients with kidney stone disease in a random way who had also at least on complete 24-h urine profile. Case and controls were matched for age, gender, and body mass index (BMI). Groups were compared to urine profile, serum exams and stone composition. RESULTS: Sixty-eight patients were enrolled in this study, 34 patients with IBD who underwent TPC and had diagnosis of kidney stones and 34 matched patients with only kidney stones. IBD patients had a significantly lower urine volume, urine citrate and urine sodium. Regarding serum exams, only serum bicarbonate was statistically significant lower. In both groups, calcium oxalate stone was the most common. CONCLUSION: Patients with IBD with TPC and kidney stones have a low urine volume and low urine citrate as main risk factors for kidney stone formation. As seen in the general population, calcium oxalate is the most common stone composition.

A probabilistic approach for benchmark dose of melamine exposure for a marker of early renal dysfunction in patients with calcium urolithiasis.

Environmental exposure to melamine has been associated with early renal injury in urolithiasis patients even when urinary concentrations of melamine are low. The aim of this study was to derive a benchmark dose (BMD) for melamine for urolithiasis patients. To do this, one-spot urine sample from 309 participants was obtained to measure urinary melamine and N-acetyl ß-D-glucosaminidase (NAG), an early renal damage biomarker. The participants were then classified into four exposure groups based on the outcomes of melamine tableware usage questionnaire. A beta distribution of urinary excretion fraction for each group was assumed to estimate their average daily intakes (AvDIs) of melamine. The BMD and the corresponding one-sided 95% lower bound (BMDL) was then derived based on Bayesian model averaging of alternative regression models between the participants' NAG levels and their estimated AvDIs, adjusting for age, gender, and other covariates. Bayesian Markov chain Monte Carlo simulations were used for all the estimates. With a benchmark response of 0.10, the simulated BMDL of 4.89 µg/kg-bw/day for melamine exposure threshold was much lower than the WHO's current recommended tolerable daily intake of 200 µg/kg_bw/day and the US FDA's 63 µg/kg_bw/day. The current regulation level of melamine might not safeguard urolithiasis patients from further deterioration of renal function.

Preliminary analysis of serum electrolytes and body mass index in patients with and without urolithiasis.

OBJECTIVES: To compare body mass index (BMI); serum parameters; and urine parameters between patients with and without urolithiasis. METHODS: Data from 1164 patients admitted to our Department of Urology from January 2011 to July 2013 were retrospectively reviewed; 714 patients (age, 5-87 years; male:female ratio, 1.8:1) exhibited urolithiasis, and 450 patients (age, 12-94 years; male:female ratio, 3.8:1) did not. Blood and urine were collected from patients the morning after hospital admission. Serum and urine parameters were checked by an automatic biochemistry analyzer. Statistical analysis included the Mann-Whitney U test and binary logistic regression. RESULTS: Serum sodium, potassium, chloride, calcium, phosphorus, and carbon dioxide combining power significantly differed between groups. In male patients, serum sodium, calcium, and phosphorus levels were higher in the urolithiasis group, whereas serum potassium and urine pH levels were lower. In female patients, serum sodium was higher in the urolithiasis group. BMI was higher in the urolithiasis group in all patients, male and female. Respective ß-values of serum sodium and BMI in male patients were 0.077 and 0.084; in female patients, these values were 0.119 and 0.102. CONCLUSIONS: Changes in serum sodium and BMI may be involved in the pathogenesis and treatment of urolithiasis.

A Particular Form of "Urolithiasis" in a Toddler.

Milk of calcium is a viscous colloidal suspension of calcium salts that forms in dilated cysts or cavities. We present, for the first time in literature, a toddler with isolated milk of calcium and treated with a conservative approach. A boy with a history of one urinary tract infection and recurrent fever without vesicoureteral reflux showed at the age of 14 months a left obstructive staghorn stone. Because of absent function of the left kidney at mercapto acetyl tri glycine scintigraphy, a JJ stent was positioned with a leak of whitish material immediately after the stent positioning. Renal scintigraphy performed 1 month later revealed a partial resumption in renal function (18%). When he was 18 months old, the child suffered episodes of acute pain with inconsolable crying, unresponsive to paracetamol administration. Ultrasound assessment revealed left pelvic dilation (anterior-posterior diameter of 18 mm), suspended echogenic debris in the bladder, and dilated left distal ureter with particulate matter. These episodes of acute pain were followed by expulsion of numerous soft formations and emission of greenish urine. Both urine culture at the admission and culture on the greenish urines were sterile. After the expulsion of the soft formations, pain episodes stopped. The diagnosis of milk of calcium stone was made. With this case, we highlight a condition that can be easily diagnosed (if known) because the morphology of the expelled material is pathognomonic. Diagnosing it could avoid unnecessary treatments (ie, extracorporeal shockwave lithotripsy) and support a conservative approach (ie, stent positioning).

Factors Associated With Compliance With 24-Hour Urine Collection.

OBJECTIVE: To identify how demographic factors, stone-associated medical comorbidities, and treatment predict compliance with 24-hour urine collection. MATERIALS AND METHODS: A retrospective medical record review of patients treated for urolithiasis between August 2014 and March 2017 was performed. Patient demographics, medical characteristics, stone factors, type of treatment, and compliance data were included for patients requested to submit a collection. Variables that were statistically significant on bivariate analysis were then used to formulate a model predicting submission of a 24-hour urine sample. RESULTS: Of the 303 patients who met inclusion criteria, 183 (60.4%) submitted an initial 24-hour urine collection. On bivariate analysis, patients older than 50 were more likely to submit a 24-hour urine collection (71.4% vs 51.5%; P <.001), patients with a metabolic predisposition for stones were more likely to submit a 24-hour urine collection (70.6% vs 53.1%; P <.003), and patients who did not have surgery were more likely to submit a 24-hour urine collection (97.9% vs 53.5%; P <.001). Our 3-variable prediction model found that not undergoing surgery was a strong predictor of 24-hour urine collection. CONCLUSIONS: We suspect that patients perceive surgery as a more definitive treatment for kidney stones than conservative management. Patient education on the natural history and role of metabolic management in the prevention of nephrolithiasis is essential in improving compliance with 24-hour urine collection.

[Urinary exploration of metabolism: nutrition assessment, urolithiasis and tubulopathy]. / Exploration urinaire du métabolisme : bilan nutritionnel, lithiase urinaire et tubulopathie.

The SFBC working group aimed to deal with biological tests outside the french nomenclature that may be useful in the context of urinary exploration of metabolism. This section will be divides into three parts: 1) nutritional assessment using urinary urea; 2) metabolic assessment of urolithiasis; 3) exploration of tubulopathies. National and international recommendations support the evaluation of nutritional status from urea measurements in urine and dialysate with the following indications: primary metabolic evaluation of urolithiasis patients, monitoring of protein intake in chronic renal failure stage 3 or stage 5D with residual diuresis. For the management of the urolithiasis disease, biomedical tests recommended by the national and international guidelines are the measurement of the urinary density using refractometry in the primary metabolic evaluation as well as the determination of oxalemia in the diagnosis (patients with GFR< 30 mL/min/1.73 m2) and follow-up (patients with GFR< 60 mL/min/1.73 m2) of primary hyperoxaluria. The determination of the bicarbonaturia is retained for the in depth exploration of urolithiasis and tubular acidosis. The measure of chlore in urine is used to evaluate the volume status during metabolic alkalosis and to calculate the urinary anionic gap during metabolic acidosis.

Urinary 2,8-dihydroxyadenine excretion in patients with adenine phosphoribosyltransferase deficiency, carriers and healthy control subjects.

BACKGROUND: Adenine phosphoribosyltransferase (APRT) deficiency is a rare autosomal recessive disorder of adenine metabolism that results in excessive urinary excretion of the poorly soluble 2,8-dihydroxyadenine (DHA), leading to kidney stones and chronic kidney disease. The purpose of this study was to assess urinary DHA excretion in patients with APRT deficiency, heterozygotes and healthy controls, using a recently developed ultra-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) assay. METHODS: Patients enrolled in the APRT Deficiency Registry and Biobank of the Rare Kidney Stone Consortium (http://www.rarekidneystones.org/) who had provided 24-h and first-morning void urine samples for DHA measurement were eligible for the study. Heterozygotes and healthy individuals served as controls. Wilcoxon-Mann-Whitney test was used to compare 24-h urinary DHA excretion between groups. Associations were examined using Spearman's correlation coefficient (rs). RESULTS: The median (range) 24-h urinary DHA excretion was 138 (64-292) mg/24 h and the DHA-to-creatinine (DHA/Cr) ratio in the first-morning void samples was 13 (4-37) mg/mmol in APRT deficiency patients who were not receiving xanthine oxidoreductase inhibitor therapy. The 24-h DHA excretion was highly correlated with the DHA/Cr ratio in first-morning void urine samples (rs = 0.84, p < .001). DHA was detected in all urine samples from untreated patients but not in any specimens from heterozygotes and healthy controls. CONCLUSIONS: High urinary DHA excretion was observed in patients with APRT deficiency, while urine DHA was undetectable in heterozygotes and healthy controls. Our results suggest that the UPLC-MS/MS assay can be used for diagnosis of APRT deficiency.