Faculty Bibliography

Introduction: This study examines the use of dialysis services by end-stage renal disease (ESRD) patients following the Superstorm Sandy-related, months-long closure of the New York campus of the US Department of Veterans Affairs (VA) New York Harbor VA Healthcare System (NYHHS, Manhattan VAMC). Methods: Outpatient visits, dialysis care, emergency department visits, and hospitalizations at VA and non-VA facilities for 47 Manhattan VAMC ESRD patients were examined 12 months pre- and post-Sandy using VA administrative and clinical data. Results: The Brooklyn campus of NYHHS, which is within ten miles of Manhattan VAMC, experienced the largest increase in the number of dialysis encounters after the closure. Dialysis encounters for VA patients also increased at non-VA facilities, rising on average, to 106 per month. For the James J Peters Bronx VAMC, the number of total dialysis encounters for Manhattan VAMC patients fluctuated between 39 and 43 per month, dropping to less than 30 after the Manhattan VAMC dialysis unit reopened. Conclusion: Manhattan VAMC ESRD patients used nearby alternate VA sites and non-VA clinics for their care during the closure of the Manhattan VAMC dialysis unit. The VA electronic health records played an important role in ensuring continuity of care for patients who exclusively used VAMC facilities post-Sandy because patient information was immediately accessible at other VA facilities. The events related to Superstorm Sandy highlight the need for dialysis providers to have a comprehensive disaster plan, including nearby alternate care sites that can increase service capacity when a dialysis facility is closed because of a disaster.

It is a question many patients ask in stone clinic - does it matter what water I drink? Often patients cite scaling up of their water pipes or kettles as demonstrating the influence that the hardness of the water has on stone formation. This article is protected by copyright. All rights reserved.

PURPOSE OF REVIEW/OBJECTIVE:The effect of the intestinal microbiome on urine chemistry and lithogenicity has been a popular topic. Here we review the evidence for exposure to antibiotics increasing the risk of nephrolithiasis. RECENT FINDINGS/RESULTS:Studies of the intestinal microbiome have focused on Oxalobacter formigenes, an anaerobe that frequently colonizes the human colon. As a degrader of fecal oxalate its presence is associated with lower urinary oxalate, which would be protective against calcium oxalate stone formation. It also appears capable of stimulating colonic oxalate secretion. A recent study showed that antibiotics can eliminate colonization with O. formigenes. In a case-control study, exposure to sulfa drugs, cephalosporins, fluoroquinolones, nitrofurantoin/methenamine, and broad spectrum penicillins prospectively increased the odds of nephrolithiasis. The effect was greatest for those exposed at younger ages and 3-6 months before being diagnosed with nephrolithiasis. SUMMARY/CONCLUSIONS:Recent evidence suggests a possible, causal role of antibiotics in the development of kidney stones. A possible explanation for this finding includes alterations in the microbiome, especially effects on oxalate-degrading bacteria like O. formigenes. Ample reasons to encourage antibiotic stewardship already exist, but the possible role of antibiotic exposure in contributing to the increasing prevalence of kidney stones in children and adults is another rationale.

The most important variable leading to uric acid stones is low urine pH. Major causal conditions associated with low urine pH are metabolic syndrome and diabetes. In the study by Maalouf et al., treatment of uric acid stone formers with pioglitazone led to small but significant increases in urine pH. Pioglitazone will not supplant alkali administration to prevent uric acid stones, but the study helps confirm that insulin resistance is an important cause of low urine pH that causes uric acid stones.

Appropriate dosing of cystine-binding thiol drugs in the management of cystinuria has been based on clinical stone activity. When new stones form, the dose is increased. Currently, there is no method of measuring urinary drug levels to guide the titration of therapy. Increasing cystine capacity, a measure of cystine solubility, has been promoted as a method of judging the effects of therapy. In this study, we gave increasing doses of tiopronin or D-penicillamine, depending on the patients' own prescriptions, to ten patients with cystinuria and measured cystine excretion and cystine capacity. The doses were 0, 1, 2, 3 g per day, given in two divided doses, and administered in a random order. Going from 0 to 1 g/day led to an increase in cystine capacity from - 39.1 to 130.4 mg/L (P < 0.009) and decreased 24 h cystine excretion from 1003.9 to 834.8 mg/day (P = 0.039). Increasing the doses from 1 to 2 to 3 g/day had no consistent or significant effect to further increase cystine capacity or decrease cystine excretion. Whether doses higher than 1 g/day have additional clinical benefit is not clear from this study. Limiting doses might be associated with fewer adverse effects without sacrificing the benefit of higher doses if higher doses do not offer clinical importance. However, trials with stone activity as an outcome would be desirable.

Background/UNASSIGNED:Nephrolithiasis is a complex phenotype influenced by both genetic and environmental factors. Previously we found a genetic component to stone disease using a sample of male twin pairs. We now report on the genetic contribution to stones in a sample of female and male twin pairs. Methods/UNASSIGNED:We conducted a classic twin study of kidney stones using the Washington State Twin Registry. Data were collected by questionnaire to obtain self-reported history of kidney stones. Univariate structural equation modeling was used to determine the relative contributions of additive genetics, common environment, and unique environment. Results/UNASSIGNED: < 0.05). Conclusions/UNASSIGNED:Nephrolithiasis in women has a heritable component less than that we again demonstrate in men. This finding may in part explain why more stone formers are men than women. Women twins demonstrated a greater effect of the unique environment on stone prevalence. The specific environmental risk factors that account for this effect are not currently known.

BACKGROUND:Volume overload and depletion both lead to high morbidity and mortality. Achieving euvolemia is a challenge in patients with end stage kidney disease on hemodialysis (HD). Blood volume analysis (BVA) uses radiolabeled albumin to determine intravascular blood volume (BV). The measured BV is compared to an ideal BV (validated in healthy controls). We hypothesized that BVA could be used in HD to evaluate the adequacy of the current clinically prescribed "estimated dry weight" (EDW) and to titrate EDW in order to improve overall volume status. We were also interested in the reproducibility of BVA results in end stage kidney disease. METHODS:Twelve adults on chronic HD were recruited; 10 completed the study. BVA (Daxor, New York, NY, USA) was used to measure BV at baseline. EDW was kept the same if the patient was deemed to be euvolemic by BVA otherwise, the prescribed EDW was changed with the aim that measured BV would match ideal BV. A second BVA measurement was done 1-3 months later in order to measure BV again. RESULTS: = 0.08). CONCLUSIONS:This pilot study is the first longitudinal measurement of BVA in HD patients. It revealed that changing weight did not proportionally change intravascular BV. BV remained stable for 1-3 months. BVA may not be helpful in clinically stable HD patients but studies on patients with hemodynamic instability and uncertain volume status are needed. TRIAL REGISTRATION/BACKGROUND:ClinicalTrials.gov (NCT02717533), first registered February 4, 2015.