When and how to evaluate a patient with nephrolithiasis

Relationship Between the ApaI (rs7975232), BsmI (rs1544410), FokI (rs2228570), and TaqI (rs731236) Variants in the Vitamin D Receptor Gene and Urolithiasis Susceptibility: An Updated Meta-Analysis and Trial Sequential Analysis

The relationship between urolithiasis and vitamin D receptor (VDR) gene variants is still under debate according to the available published literature. To assess correlations between VDR gene variants ApaI (rs7975232), BsmI (rs1544410), FokI (rs2228570), and TaqI (rs731236) and urolithiasis susceptibility, we performed the present study through meta-analysis. The PubMed, Cochrane Library, China National Knowledge Infrastructure, EMBASE, Web of Science, and Wanfang databases were searched to retrieve qualified case-control studies. Finally, 31 reports were selected for the present meta-analysis. The results demonstrated that the VDR gene TaqI TT genotype was related to decreased risk of urolithiasis in the overall population (TT vs. Tt+tt: P = 0.011, OR = 0.824, 95% CI = 0.709–0.957). In ethnicity subgroup analysis, we found that the TaqI variant was obviously correlated to urolithiasis risk among Asians and Caucasians (P < 0.05). Additionally, significant urolithiasis risk was identified in adults. However, the FokI, BsmI, and ApaI variants did not have an increased risk of developing urolithiasis. Trial sequential analysis results were on a sufficiently large number of participants and did not require more research to confirm associations. Our research suggested that the VDR gene variant TaqI was correlated with urolithiasis susceptibility and that the t-allele might be the risk gene and T-allele the protective gene in VDR TaqI variant.

Potassium Citrate Supplementation Decreases the Biochemical Markers of Bone Loss in a Group of Osteopenic Women: The Results of a Randomized, Double-Blind, Placebo-Controlled Pilot Study

The relationship involving acid-base imbalance, mineral metabolism and bone health status has previously been reported but the efficacy of the alkalizing supplementation in targeting acid overload and preventing bone loss has not yet been fully elucidated. In this randomized, double-blind, placebo-controlled study, the hypothesis that potassium citrate (K citrate) modifies bone turnover in women with postmenopausal osteopenia was tested. Three hundred and ten women were screened; 40 women met the inclusion criteria and were randomly assigned to the treatment or the placebo group. They were treated with K citrate (30 mEq day⁻¹) or a placebo in addition to calcium carbonate (500 mg day⁻¹) and vitamin D (400 IU day⁻¹). At baseline and time points of 3 and 6 months, serum indicators of renal function, electrolytes, calciotropic hormones, serum bone turnover markers (BTMs) (tartrate-resistant acid phosphatase 5b (TRACP5b), carboxy-terminal telopeptide of type I collagen (CTX), bone alkaline phosphatase (BAP), procollagen type 1 N terminal propeptide (PINP)), and urine pH, electrolytes, and citrate were measured. The follow-up was completed by 17/20 patients in the “K citrate” group and 18/20 patients in the “placebo” group. At baseline, 90% of the patients exhibited low potassium excretion in 24 h urine samples, and 85% of cases had at least one urine parameter associated with low-grade acidosis (low pH, low citrate excretion). After treatment, CTX and BAP decreased significantly in both groups, but subjects with evidence of low-grade acidosis gained significant benefits from the treatment compared to the placebo. In patients with low 24h-citrate excretion at baseline, a 30% mean decrease in BAP and CTX was observed at 6 months. A significant reduction was also evident when low citrate (BAP: −25%; CTX: −35%) and a low pH (BAP: −25%; CTX: −30%) were found in fasting-morning urine. In conclusion, our results suggested that K citrate supplementation improved the beneficial effects of calcium and vitamin D in osteopenic women with a documented potassium and citrate deficit, and a metabolic profile consistent with low-grade acidosis.

Effects of vitamin D receptor polymorphisms on urolithiasis risk: a meta-analysis

Background

Several studies analyzed the associations of Vitamin D receptor (VDR) polymorphisms with urolithiasis risk in different ethnic groups. However, the results were inconclusive. To evaluate a more precise estimation of the relationship, a meta-analysis was performed.

Methods

Pubmed, EMBASE, Wanfang Database, China National Knowledge Infrastructure (CNKI) and Weipu Database were searched. Data were extracted independently by two investigators. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations.

Results

Twenty-three case–control studies were included in this meta-analysis. Significant associations between ApaI, BsmI, FokI, and TaqI polymorphisms and urolithiasis risk were observed. However, sensitivity analyses for BsmI and FokI polymorphisms indicated that the results were not reliable and credible. In addition, there was a significant association of the ApaI-TaqI haplotype with urolithiasis risk.

Conclusions

This meta-analysis suggested that ApaI and TaqI polymorphisms in VDR gene were associated with urolithiasis risk.

Curative treatment with extracts of Bombax ceiba fruit reduces risk of calcium oxalate urolithiasis in rats

CONTEXT

Drawbacks of presently available treatments for urolithiasis necessitate finding the treatment of hyperoxaluria specifically aimed at reduction in oxalate excretion. Interestingly, many Indian tribes use Bombax ceiba L. (Bombacaceae) fruits as a traditional medicine for the treatment of urinary stones.

OBJECTIVE

The present study investigated the efficacy of B. ceiba fruit extracts as curative agents in experimentally induced calcium oxalate urolithiatic rats.

MATERIALS AND METHODS

Calcium oxalate lithiasis was induced in rats by oral administration of 0.75% ethylene glycol for 14 consecutive days. Treatments with aqueous and ethanol extract of B. ceiba fruit (400 mg/kg body weight) was performed in the same manner for further 14 consecutive days. Cystone (750 mg/kg body weight) was used as reference antiurolithiatic drug. The urinary excretion and kidney deposition of offending salt components, and serum biochemical parameters were investigated.

RESULTS

Oral administration of ethylene glycol resulted in hyperoxaluria and increased renal excretion of calcium and phosphate. However, supplementation with aqueous and ethanol extracts of B. ceiba fruit significantly (p < 0.05) reduced the elevated urinary oxalate, showing a regulatory action on endogenous oxalate synthesis. The increased deposition of stone forming constituents in kidneys of calculogenic rats was also significantly lowered with curative treatment of aqueous and ethanol extract.

DISCUSSION AND CONCLUSION

The results indicate that the fruit of B. ceiba is endowed with lithontriptic activity warranting further development for curative treatment of urolithiasis.

Biochemical determinants of severe lithogenic activity in patients with idiopathic calcium nephrolithiasis

OBJECTIVE

To analyze the biochemical alterations in plasma and the urine determinants of severe lithogenic activity in patients with idiopathic calcium nephrolithiasis.

METHODS

We performed a cross-sectional study of 120 patients divided into 2 groups: group 1, 60 patients without nephrolithiasis; and group 2, 60 patients with severe and/or recurrent calcium nephrolithiasis. In all patients, a study of renal function, calcium metabolism, and bone remodeling markers, and a study of the lithogenic factors were performed in urine after fasting and in 24-hour urine samples.

RESULTS

We observed greater values for phosphorus in group 1 than in group 2 (P=.03). Also, we found greater values for intact parathyroid hormone (P=.01), osteocalcin (P=.000), and β-crosslaps (P=.000) in group 2 than in group 1. In the 24-hour urine samples, significant differences were found between groups 1 and 2 in calciuria (11.7 vs 17.4 mg/dL; P=.000), citraturia (50.6 vs 33.5 mg/dL; P=.002), calcium/creatinine quotient (0.14 vs 0.20; P=.001), calcium/citrate quotient (0.05 vs 0.13; P=.04), and calcium/creatinine quotient after fasting (0.09 vs 0.16; P=.000).

CONCLUSION

We consider the determinants of severe and/or recurrent calcium lithiasis to be hypercalciuria and hypocitraturia and a calcium/citrate quotient>0.06. As risk markers we can consider phosphatemia<2.9 mg/dL, phosphate/chlorine quotient>35, alkaline phosphatase>80 U/L, intact parathyroid hormone>60 pg/mL, osteocalcin>16 ng/mL, β-crosslaps>0.400 ng/mL, and β-crosslaps/osteocalcin quotient>0.028.

Approach to the Adult Kidney Stone Former

Nephrolithiasis is a prevalent and costly condition with high recurrence rate. A medical evaluation to identify abnormalities responsible for nephrolithiasis and guide subsequent therapy has been advocated to reduce the risk of stone recurrence. The evaluation of kidney stone formers generally comprises an extensive medical history to identify metabolic, environmental, dietary and/or genetic factors contributing to stone formation. Imaging studies are utilized to evaluate and follow stone burden. Laboratory studies including stone composition analysis and serum and urinary chemistries are commonly obtained to further assess for any underlying systemic disorders, to detect environmental and metabolic processes contributing to stone disease, and to guide initial and follow-up dietary and pharmacological therapy. The nature and extent of such an evaluation is discussed in this review article.

Application of a new method for GWAS in a related case/control sample with known pedigree structure: identification of new loci for nephrolithiasis

In contrast to large GWA studies based on thousands of individuals and large meta-analyses combining GWAS results, we analyzed a small case/control sample for uric acid nephrolithiasis. Our cohort of closely related individuals is derived from a small, genetically isolated village in Sardinia, with well-characterized genealogical data linking the extant population up to the 16(th) century. It is expected that the number of risk alleles involved in complex disorders is smaller in isolated founder populations than in more diverse populations, and the power to detect association with complex traits may be increased when related, homogeneous affected individuals are selected, as they are more likely to be enriched with and share specific risk variants than are unrelated, affected individuals from the general population. When related individuals are included in an association study, correlations among relatives must be accurately taken into account to ensure validity of the results. A recently proposed association method uses an empirical genotypic covariance matrix estimated from genome-screen data to allow for additional population structure and cryptic relatedness that may not be captured by the genealogical data. We apply the method to our data, and we also investigate the properties of the method, as well as other association methods, in our highly inbred population, as previous applications were to outbred samples. The more promising regions identified in our initial study in the genetic isolate were then further investigated in an independent sample collected from the Italian population. Among the loci that showed association in this study, we observed evidence of a possible involvement of the region encompassing the gene LRRC16A, already associated to serum uric acid levels in a large meta-analysis of 14 GWAS, suggesting that this locus might lead a pathway for uric acid metabolism that may be involved in gout as well as in nephrolithiasis.

Adequacy of a single 24-hour urine collection for metabolic evaluation of recurrent nephrolithiasis

PURPOSE

There is much debate about whether 1 or 2, 24-hour urinalyses are adequate for metabolic evaluation of stone formers. We determined whether repeat 24-hour urine collection provides information similar to that of the initial 24-hour urine collection and whether repeat collection is necessary.

MATERIALS AND METHODS

We analyzed 2, 24-hour urine collections in 777 patients obtained from 2001 to 2005. Samples were collected 3 days or less apart before pharmacological intervention and analyzed elsewhere for routine stone risk profiles of urine calcium, oxalate, citrate, uric acid, sodium, potassium, magnesium, phosphorus, ammonium, chloride, urea nitrogen and creatinine.

RESULTS

No parameters showed a statistically significant difference between 24-hour urine samples 1 and 2 when mean values were compared (pairwise t test each p >0.05, range 0.06 to 0.87). Using Pearson's correlation all parameters showed positive correlation coefficients (r = 0.68 to 0.89, each p <0.0001). The mean of individual patient differences in samples 1 and 2 were compared to 0 and 6 of 12 showed no difference (p >0.05) while for the remaining 6 p value was <0.05. The percent difference was 0.5% to 4.19% for all urinary parameters.

CONCLUSIONS

One 24-hour urine sample is sufficient for metabolic evaluation of recurrent stone disease. There is no significant difference in 12 urinary parameters between 24-hour urine samples collected within 3 days of each other. This information is useful to providers and may decrease patient inconvenience and the overall cost of metabolic stone evaluation.

Detection of renal calculi on late arterial phase computed tomography images: are noncontrast scans always needed to detect renal calculi?

OBJECTIVE

Renal calculi are sometimes incidentally detected on contrast-enhanced computed tomography (CT) scans. The purpose of this study was to evaluate the detectability of renal calculi on arterial phase CT.

METHODS

One hundred thirty-three kidneys of 67 consecutive patients (one had prior unilateral nephrectomy) who underwent multidetector CT including noncontrast and arterial phase (acquired at 25 seconds from the start of 120 mL of intravenous contrast injection at a rate of 3 mL/s) scans were retrospectively evaluated. The detectability of renal calculi was determined by comparison of the noncontrast and contrast-enhanced scans.

RESULTS

Sixty-three calculi in 25 kidneys were detected in 17 patients on noncontrast CT. Forty-seven (75%) of the 63 calculi were also detected on the arterial phase scans. The size and highest attenuation of calculi (measured on noncontrast CT) detected on arterial phase scans were 4.3 +/- 3.0 mm and 556 +/- 353 Hounsfield units, and those detected only on noncontrast CT were 2.8 +/- 0.8 mm (P = 0.053) and 181 +/- 47 Hounsfield units (P < 0.0001), respectively. All calculi larger than 5 mm were detected on arterial phase scans.

CONCLUSIONS

On arterial phase scans, 75% of the renal calculi and allrenal calculi larger than 5 mm were detected; the attenuation of the calculi had a significant correlation to detectability.

Predisposition of genetic polymorphism with the risk of urolithiasis

Urolithiasis is a relevant clinical problem with a subsequent burden for health system. The aim of this review is to provide recent progress made using genetic polymorphisms to define pathophysiology, to identify persons at risk for kidney stone disease and to predict treatment response. Population case-control studies are useful both as an alternative and an adjunct as compared to family studies. These involve either whole genome scanning or candidate gene approaches. While whole genome scanning is likely to be widely used in future, at present, candidate gene studies are more feasible. When performing candidate gene case-control studies factors such as study design, methods for recruitment of case and controls, selection of candidate genes, functional significance of polymorphisms chosen for study and statistical analysis require close attention to ensure that only genuine associations are detected. Some of the significant genes that play role in stone formation include calcitonin receptor gene (CTR), vitamin D receptor (VDR), Urokinase, Interleukin, (IL-1β, IL-Ra), E-Cadherin, Androgen & oestrogen receptor gene, vascular endothelial growth factor (VEGF) and Arginine p21. In our case-control study we studied CTR, VDR, Urokinase, IL-1β(-511 and +3954), IL-Ra from north India and predict that VDR, IL-β (-511) and IL-1Ra gene may be used as a possible genetic marker for earlier detection in patients who are at risk for calcium oxalate stone disease. Further, linkage disequilibrium and haplotype structure of a certain candidate gene is important for association analysis. When a certain polymorphic allele has been found to be associated with disease, it is further explained on basis of LD and haplotype structure by one or more other alleles. Once it is determined which haplotype carries the risk allele, by means of molecular biological functional analyses, the variants on that haplotype allele truly causing the effect can be determined.

Prognostic factors effecting on recurrence of urinary stone disease: a multivariate analysis of everyday patient parameters

INTRODUCTION

Since comprehensive urometabolic analyses are currently more preferred for the patients with recurrent stones and with high risk of stone recurrence, we have tried to determine simple patient data increasing stone recurrence to limit sophisticated analyses to certain cases at least in particularly deprivation districts.

MATERIALS AND METHODS

For the study 173 with first-time or recurrent urinary stone were taken. After stone treatment, various empirical metaphylaxis methods were counselled to the patients. The parameters evaluated were (a) age at onset of the disease, (b) gender, (c) urinary pH and (d) specific gravity, (e) serum calcium and (f) uric acid, (g) stone burden, (h) side, and (i) location, (j) treatment modality and (k) recurrence history. New stone formation or growing of the existing stone was considered as stone recurrence. In statistics, independent samples t, chi-square test, Kaplan-Meier, Log rank and Cox regression tests were used.

RESULTS

The mean age was 35 years. The male to female ratio was 88/85. Recurrence occurred in 49 (28%) cases at a mean of 30 months. Stone burden was significantly larger in patients with recurrent stone. In subjects treated with open surgery and with previous recurrence history, stone recurrence rate was significantly higher. In survival analyses, higher serum calcium level, larger stone burden, renal stones and previous recurrence influenced stone prognosis poorly. However in multivariate analysis, none of them was the most significant independent factor.

CONCLUSIONS

According to our study, detailed urometabolic analyses may be somewhat reserved for the patients with ordinary factors increasing risk of stone recurrence including relatively high serum calcium level, large stone burden, upper urinary stone, history of recurrence and open surgery. As a result, it has been thought that the stone risk evaluation guiding detailed laboratory examination may be partially performed with first-line clinical data under limited conditions.

Experience with marginal living related kidney donors: Are they becoming routine or are there still any doubts?

OBJECTIVES

To analyze donor and recipient outcome of grafts from marginal kidney donors (ie, elderly or suffering from some anomaly).

METHODS

We had 81 marginal donors from July 1996 to July 2004; 46 were older than 60 years, and 39 had renal or nonrenal anomaly. The donors and recipients were evaluated for morbidity, graft and recipient survival, and the number of rejection episodes.

RESULTS

The mean (+/- standard deviation) age of elderly donors was 62.2 +/- 3.1 years. Follow-up ranged from 6 months to 50 months (mean 21.15 +/- 0.9 months). Actuarial 1-year and 3-year graft survival rates were 95% and 81%, respectively. Twenty-six percent of recipients maintained serum creatinine levels less than 1.4 mg/dL. The mean age of hypertensive donors was 46.2 years, and blood pressure was controlled with one drug. Serum creatinine levels in the recipients were less than 1.4 mg/dL in 10 and less than 2.5 mg/dL in the rest. Eleven percent of hypertensive donors required an increase in their antihypertensive medication. All donors showed a 15% to 20% increase in their glomerular filtration rate. Donors underwent simultaneous surgery when indicated.

CONCLUSIONS

Criteria to reject donors need to be reviewed periodically. The elderly and donors with other anomalies are consistently showing acceptable results. Hypertensive donors require assessment with awake ambulatory blood pressure monitoring.

Cellular and molecular gateways to urolithiasis: a new insight

Urolithiasis is a relevant clinical problem in everyday practice with a subsequent burden for the health system. Urolithiasis is classically explained as the derangement in the process of biomineralization involving the equilibrium between promoters and inhibitors of crystallization: a deficit of one or several inhibitors or an excess of one or several promoters plays a pivotal role in the stone formation. The revolutionary introduction of the molecular biology in medicine has given a new insight in urolithiasis too. Genetic factors have also been postulated to play an important role. A review of the current knowledge on urolithiasis based upon a molecular and genetic approach is reported.

Amitriptyline eliminates calculi through urinary tract smooth muscle relaxation

BACKGROUND

We investigated the effects of amitriptyline in the urinary tract smooth muscle and urolithiasis.

METHODS

Cats presenting with obstructive acute renal failure (ARF) received amitriptyline, and renal function and survival rates were analyzed. Isometric contractions and membrane potentials of rat, pig, or human isolated urinary tract smooth muscle were recorded in the presence or absence of amitriptyline.

RESULTS

Twenty cats with obstructive ARF caused by urethral plugs received amitriptyline. In all cases, plugs were completely eliminated, and renal function returned to normal, with a 100% survival rate in the follow-up. Amitriptyline produced potent relaxations in rat urethral strips, accompanied by significant reductions in urethral ring membrane potential. This effect was prevented by pretreatment of urethral rings with 4-aminopyridine (4-AP), a voltage-dependent potassium channel blocker. Amitriptyline abolished in a reversible manner acetylcholine-, bradykinin-, and KCl-induced contractions in rat isolated bladder, and this effect was also prevented by 4-AP. Of interest, spontaneous and KCl-induced contractions of pig and human isolated ureter were also blocked by amitriptyline.

CONCLUSION

Our results indicate that amitriptyline is an effective and potent relaxant of urinary tract smooth muscle and this effect is mediated by opening of voltage dependent-potassium channels. We suggest that amitriptyline administration may help to promote elimination of urinary calculi.

Identification of a novel gene and a common variant associated with uric acid nephrolithiasis in a Sardinian genetic isolate

Uric acid nephrolithiasis (UAN) is a common disease with an established genetic component that presents a complex mode of inheritance. While studying an ancient founder population in Talana, a village in Sardinia, we recently identified a susceptibility locus of approximately 2.5 cM for UAN on 10q21-q22 in a relatively small sample that was carefully selected through genealogical information. To refine the critical region and to identify the susceptibility gene, we extended our analysis to severely affected subjects from the same village. We confirm the involvement of this region in UAN through identical-by-descent sharing and autozygosity mapping, and we refine the critical region to an interval of approximately 67 kb associated with UAN by linkage-disequilibrium mapping. After inspecting the genomic sequences available in public databases, we determined that a novel gene overlaps this interval. This gene is divided into 15 exons, spanning a region of approximately 300 kb and generating at least four different proteins (407, 333, 462, and 216 amino acids). Interestingly, the last isoform was completely included in the 67-kb associated interval. Computer-assisted analysis of this isoform revealed at least one membrane-spanning domain and several N- and O-glycosylation consensus sites at N-termini, suggesting that it could be an integral membrane protein. Mutational analysis shows that a coding nucleotide variant (Ala62Thr), causing a missense in exon 12, is in strong association with UAN (P=.0051). Moreover, Ala62Thr modifies predicted protein secondary structure, suggesting that it may have a role in UAN etiology. The present study underscores the value of our small, genealogically well-characterized, isolated population as a model for the identification of susceptibility genes underlying complex diseases. Indeed, using a relatively small sample of affected and unaffected subjects, we identified a candidate gene for multifactorial UAN.

Integration of text, image, and graphic data from different sources in laboratory reports: example of kidney stone reporting system

Laboratory analyses may generate multiple data types that may reside in disparate systems, and combining data into a report often requires laborious, error-prone methods. Kidney stone analysis, which includes biochemical composition analysis and gross feature documentation, is an example of such a situation. We developed the kidney stone reporting system (KISS) that integrates patient and specimen information from the laboratory information system, digital images of stones, and analytic instrument data into a concise report for the ordering clinicians. The database management environment facilitates archival and retrieval capabilities. Implementation of the system has reduced the number of manual steps necessary to produce a report and has saved approximately 30 technologist hours per week. Transcription errors have been virtually eliminated. The KISS represents an innovative use of standard tools to integrate text, image, and graphic data from disparate systems into an integrated laboratory report, without the need for expensive interfaces.

Identification of a new candidate locus for uric acid nephrolithiasis

Renal stone formation is a common multifactorial disorder, of unknown etiology, with an established genetic contribution. Lifetime risk for nephrolithiasis is approximately 10% in Western populations, and uric acid stones account for 5%-10% of all stones, depending on climatic, dietary, and ethnic differences. We studied a small, isolated founder population in Sardinia, characterized by an increased prevalence of uric acid stones, and performed a genomewide search in a deep-rooted pedigree comprising many members who formed uric acid renal stones. The pedigree was created by tracing common ancestors of affected individuals through a genealogical database based on archival records kept by the parish church since 1640. This genealogical information was used as the basis for the study strategy, involving screening for alleles shared among affected individuals, originating from common ancestors, and utilization of large pedigrees to obtain greater power for linkage detection. We performed multistep linkage and allele-sharing analyses. In the initial stage, 382 markers were typed in 14 closely related affected subjects; interesting regions were subsequently investigated in the whole sample. We identified two chromosomal regions that may harbor loci with susceptibility genes for uric acid stones. The strongest evidence was observed on 10q21-q22, where a LOD score of 3.07 was obtained for D10S1652 under an affected-only dominant model, and a LOD score of 3.90 was obtained using a dominant pseudomarker assignment. The localization was supported also by multipoint allele-sharing statistics and by haplotype analysis of familial cases and of unrelated affected subjects collected from the isolate. In the second region on 20q13.1-13.3, multipoint nonparametric scores yielded suggestive evidence in a approximately 20-cM region, and further analysis is needed to confirm and fine-map this putative locus. Replication studies are required to investigate the involvement of these regions in the genetic contribution to uric acid stone formation.