Faculty Bibliography

PURPOSE/UNASSIGNED:Urine calcium excretion is greater after dinner and urine volumes are lower. The result is higher urine calcium concentrations, which may confer greater risk of stone formation, at night. We considered whether night-time administration - as compared with daytime administration - of thiazides would be more effective for stone prevention. MATERIALS AND METHODS/UNASSIGNED:We performed 12-hour urine collections in 7 patients taking 25 mg of chlorthalidone (CTD) and 10 patients taking 25 mg of hydrochlorothiazide (HCTZ). Participants completed urine collections at baseline, again after a week of morning medication administration, and again after a week of evening administration, all on repeated self-selected diets. RESULTS/UNASSIGNED:Chlorthalidone reduced urine calcium excretion for both 12-hour periods whether administered in the morning or in the evening: morning dosing lowered urine calcium from 130±70 mg/gram Cr at baseline, to 76±52 mg/gram Cr (P<0.02); evening dosing lowered it to 87±51 mg/gram Cr, which was not significant. On the other hand, HCTZ did not reduce urine calcium excretion regardless of the time of administration: mean 24-hour urine calcium excretion (UCa) was 124±38 mg/gram Cr at baseline and 106±40 mg/gram Cr when HCTZ was given in AM, and 117±54 mg/gram Cr when given in PM. CONCLUSION/UNASSIGNED:We conclude that the long-acting and more effective CTD is a preferable agent for stone prevention. Time of administration does not appear to be important, although morning administration may more effectively address higher post-dinner calcium excretion. The most commonly used thiazide (HCTZ) is shorter acting, frequently dosed once per day, but does not appear to reduce urine calcium excretion at this dose.

PURPOSE OF REVIEW/OBJECTIVE:Initiation of hemodialysis treatment with a thrice-weekly prescription is currently the standard of care irrespective of patients' residual kidney function (RKF), comorbidities, and preferences. RECENT FINDINGS/RESULTS:Each year ∼12 000 Veterans with advanced kidney disease progress to end-stage kidney disease (ESKD) requiring dialysis and comprise greater than 10% of the US incident ESKD population. Dialysis is costly and is associated with impaired health-related quality of life (HRQOL) and high mortality risk, especially in the first year of treatment. Evidence suggests an incremental dialysis transition using twice-weekly hemodialysis provides various benefits, including more dialysis-free time, longer RKF preservation, less vascular access damage, and lower patient burden. Pragmatic studies are needed to inform the efficacy and safety of incremental hemodialysis as a personalized dialysis regimen, and could inform its consideration as a conservation strategy during times of supply shortages. Broadly implementing twice-weekly hemodialysis could also potentially allow more Veterans to receive care within VA-based dialysis units. The VA IncHVets Trial is a pragmatic, multicenter, randomized controlled trial comparing the efficacy and safety of twice-weekly incremental vs. thrice-weekly hemodialysis among Veterans transitioning to ESKD. SUMMARY/CONCLUSIONS:Further research is needed to determine whether incremental hemodialysis is well tolerated, effective, and facilitates a more favorable transition to dialysis.

OBJECTIVE:In people with chronic kidney disease (CKD), hyperphosphatemia is a risk factor for mortality. Though unproven, dietary phosphorus control is considered essential in CKD. Although dietary and serum phosphorus are correlated, phosphorus from plant foods rich in phytate is less bioavailable than from animal and processed foods. Yogurt, valued for its low phosphorus and high protein, may be detrimental in CKD due to animal protein content. Plant-based yogurts (PBYs) might offer similar benefits without the downsides of animal protein, but little is known about their phosphorus content. DESIGN AND METHODS/METHODS:Protein contents and phosphorus additives were gathered from nutrition labels of several PBYs, including almond, cashew, oat, coconut, and soy substrates. Phosphorus content was measured via emission spectrometry by Eurofins (Madison, WI), and the phosphorus-to-protein ratio (PPR) was calculated for each PBY. RESULTS:Phosphorus content was highest in Silk Soy Strawberry, Silk Almond Strawberry, and Siggi's Coconut Mixed Berries, while it was lowest in So Delicious Coconut Strawberry, Oatly Oat Strawberry, Forager Cashew Strawberry, and Kite Hill Almond Strawberry. Ingredient labels revealed that Silk Soy Strawberry, Silk Almond Strawberry, and Oatly Oat Strawberry contained phosphorus additives, and Siggi's Coconut Mixed Berries contained pea protein additives. Though from the same substrate class, So Delicious Coconut Strawberry and Siggi's Coconut Mixed Berries showed significant differences in phosphorus and protein contents. All seven PBYs had higher PPR ratios than dairy yogurts like Stonyfield Organic Oikos Strawberry, Chobani Nonfat Strawberry, and Yoplait Greek Strawberry. CONCLUSION/CONCLUSIONS:Low-PPR foods are important for CKD patients. Siggi's Coconut Mixed Berries had the lowest PPR, making it potentially the most desirable for CKD patients. However, there is high variability in PPR among PBYs with the same substrate; therefore, Delicious Coconut Strawberry had the highest PPR, highlighting the importance of product selection for patients with CKD.

BACKGROUND:Identifying factors associated with uncomplicated and complicated opioid use is essential, especially with regard to safety concerns in impaired kidney function. Literature about opioid prescription and their potential complications in patients with different stages of chronic kidney disease (CKD) is scarce. This study describes opioid use and poisoning in hospitalized CKD patients. METHODS:The National Inpatient Database (NIS) was queried from 2016 to 2020 to identify which patients with known CKD stages were admitted with diagnoses of uncomplicated and complicated opioid use, and opioid poisoning. Patients with end-stage kidney disease receiving any form of renal replacement therapy were excluded. CKD1 served as a reference, and demographic and socio-economic characteristics were accounted for. Logistic regressions were performed to evaluate the relationship between CKD stages and each condition. RESULTS:The final cohort included 2,917,404 (14,587,017 weighted) CKD patients, of whom 1.763 ± 0.023% and 1.177 ± 0.016% had uncomplicated and complicated opioid use, respectively. Odds of uncomplicated use were lower with more advanced CKD stages. We observed an increase of complicated use with milder forms of CKD. No differences in odds of complicated opioid use were found when CKD4-5 patients were compared to CKD1. After adjustment, opioid use was found to be the main predictor of poisoning in hospitalized CKD patients. CONCLUSION/CONCLUSIONS:Prescribers appear to be more cautious in patients with advanced CKD, with lower odds of being on opioid analgesics in this group. Most CKD patients had higher odds of complicated use, and poisoning was essentially driven by complicated opioid use rather than CKD stage.

PURPOSE OF REVIEW/OBJECTIVE:Extremes of weather as a result of climate change are affecting social, economic and health systems. Kidney health is being threatened by global warming while treatment of kidney disease is contributing to increasing resource utilization and leaving a substantial carbon footprint. Improved physician awareness and patient education are needed to mitigate the risk. RECENT FINDINGS/RESULTS:Rising temperatures are changing kidney disease patterns, with increasing prevalence of acute kidney injury, chronic kidney disease and kidney stones. These issues disproportionately affect people suffering from social inequality and limited access to resources. SUMMARY/CONCLUSIONS:In this article, we review the effects of climate change on kidney stones, and acute and chronic kidney injury. Finally, we discuss the impact of renal replacement therapies on the environment and proposed ways to mitigate it.

INTRODUCTION/UNASSIGNED:Hyperoxaluria is a risk factor for kidney stone formation and chronic kidney disease progression. The microbiome is an important protective factor against oxalate accumulation through the activity of its oxalate-degrading enzymes (ODEs). In this cross-sectional study, we leverage multiomics to characterize the microbial community of participants with primary and enteric hyperoxaluria, as well as idiopathic calcium oxalate kidney stone (CKS) formers, focusing on the relationship between oxalate degrading functions of the microbiome. METHODS/UNASSIGNED:Patients diagnosed with type 1 primary hyperoxaluria (PH), enteric hyperoxaluria (EH), and CKS were screened for inclusion in the study. Participants completed a food frequency questionnaire recording their dietary oxalate content while fecal oxalate levels were ascertained. DNA and RNA were extracted from stool samples and sequenced. Metagenomic (MTG) and metatranscriptomic (MTT) data were processed through our bioinformatics pipelines, and microbiome diversity, differential abundance, and networks were subject to statistical analysis in relationship with oxalate levels. RESULTS/UNASSIGNED:A total of 38 subjects were recruited, including 13 healthy participants, 12 patients with recurrent CKS, 8 with PH, and 5 with EH. Urinary and fecal oxalate were significantly higher in the PH and the EH population compared to healthy controls. At the community level, alpha-diversity and beta-diversity indices were similar across all populations. The respective contributions of single bacterial species to the total oxalate degradative potential were similar in healthy and PH subjects. MTT-based network analysis identified the most interactive bacterial network in patients with PH. Patients with EH had a decreased abundance of multiple major oxalate degraders. CONCLUSION/UNASSIGNED:The composition and inferred activity of oxalate-degrading microbiota were differentially associated with host clinical conditions. Identifying these changes improves our understanding of the relationships between dietary constituents, microbiota, and oxalate homeostasis, and suggests new therapeutic approaches protecting against hyperoxaluria.

Andersson NW, Wohlfahrt J, Feenstra B, et al. Cumulative incidence of thiazide-induced hyponatremia: a population-based cohort study. Ann Intern Med. 2024;177:1-11. 38109740.

PURPOSE OF REVIEW/OBJECTIVE:Continuous renal replacement therapy (CRRT) is a vital medical intervention used in critically ill patients with acute kidney injury (AKI). One of the key components of adequate clearance with CRRT is the use of anticoagulants to prevent clotting of the extracorporeal circuit. Regional citrate anticoagulation is the most often recommended modality. The term 'citrate toxicity' is used to describe potential adverse effects of accumulation of citrate and subsequent hypocalcemia. However, citrate is itself not inherently toxic. The term and diagnosis of citrate toxicity are questioned in this review. RECENT FINDINGS/RESULTS:Citrate is being increasingly used for regional anticoagulation of the CRRT circuit. Citrate accumulation is infrequent and can cause hypocalcemia and metabolic alkalosis, which are potential adverse effects. Citrate itself, however, is not a toxic molecule. The term 'citrate toxicity' has been used to denote hypocalcemia and metabolic acidosis. However, citrate administration is well known to cause systemic and urinary alkalinization and under certain circumstances, metabolic alkalosis, but is not associated itself with any 'toxic' effects.We review the existing literature and debunk the perceived toxicity of citrate. We delve into the metabolism and clearance of citrate and question current data suggesting metabolic acidosis occurs as the result of citrate accumulation. SUMMARY/CONCLUSIONS:In conclusion, this article calls into question prevailing concerns about 'citrate toxicity'. We emphasize the need for a more nuanced understanding of its safety profile. We recommend discarding the term 'citrate toxicity' in favor of another frequently used, but more meaningful term: 'citrate accumulation'.