Faculty Bibliography

Background: Urine chemistry is a determinant of stone formation in cystinuria. We previously showed that positive cystine capacity (CysCap), a measure of higher cystine solubility, led to fewer stone events. We queried the RKSC Cystinuria Registry to determine urinary and medication variables associated with positive (CysCap+), rather than negative (CysCap-) values.
Method(s): This is the 1st report from the Cystinuria Registry, with data on 300 people with cystinuria (142 males, 158 females; age at enrollment 38 +/- 17 years). 112 participants had 306 determinations of CysCap, measured by Litholink (Chicago, IL). In this cross-sectional study we compared variables associated with CysCap+ vs CysCap-.
Result(s): Lower urine Na (r=0.48; Fig 1A) and creatinine (r=0.62, not shown) were associated with lower 24h urine cystine (UC; P<0.001). Increasing CysCap values were seen with increasing urine pH (rs=0.45, Fig 1B), volume (rs=0.44) and decreasing UC (rs=-0.44 Fig 1C; all P<0.001). Dividing Cyscap determinations into CysCap+ and CysCapgroups (Table), only higher urine volume and greater daily citrate doses were different. Relatively few participants were taking citrate or tiopronin.
Conclusion(s): Higher urine pH and volume and lower UC were associated with less lithogenic urine; lower UC was seen with less Na and creatinine. Higher volume and citrate doses distinguished patients with less lithogenic urine. Many patients with cystinuria may be undertreated and would benefit from better dietary adherence. (Table Presented)

Background: The assessment of HRQoL in RKSF is important for following disease course and evaluating treatment. Previously, using a non-disease specific instrument we showed that RKSF present differently, with the worst domain scores in cystinuria. These are the first follow-up data based on summary scores for adults in a cross-sectional comparison.
Method(s): RKSF were enrolled from 4 RKSC registries: primary hyperoxaluria, cystinuria, Dent disease and APRTd. HRQoL is measured with the generic non-disease specific SF-36v2. Results are norm-based scores (NBS) based on US Standard Population (Domain score mean = 50). Group means < 47 indicate the presence of impaired functioning in associated dimension.
Result(s): We scored 545 surveys of the adult population at different time points, adjusted for the last stone event and compared the Physical and Mental Component Scores (PCS and MCS). We found the lowest PCS in Dent, and the highest in PH. The lowest MCS was found in cystinuria, the highest was found in PH. Low PCS indicate restrictions in self-care, physical, social and role activities; bodily pain, tiredness and poor rated health. Low MCS are associated with frequent psychological distress, social and role disability due to emotional problems, and poor rated health. Participants with cystinuria reported more stone events with related procedures than other RKSF (X2 (9) 23.375, p=.005).
Conclusion(s): HRQoL in RKSF is influenced by stone events and can be assessed with a non-disease specific SF-36v2. Adjusting for time between the survey and last event allows for the interpretation of more meaningful HRQoL profiles. The time from the last stone event and related procedures affect HRQOL in RKSF significantly. (Table Presented)

Background: USD is a preventable disease characterized by significant risk of recurrence. A "cascade of care" shows how many patients are lost to follow-up at diagnosis, referral, and treatment and is a useful tool in delivering HIV care. We can analyze our success, or failure, in the secondary prevention of kidney stones and retention of patients by constructing a cascade of care.
Method(s): We abstracted data from observational studies to identify impediments to care of patients with USD Results: In the US there are about 1.2 million ER visits per year. 37% of patients diagnosed with stones receive a follow-up consultation with a urologist and fewer see a nephrologist. Although 24h urine collection results may decrease stone recurrence rate, only 7.4% do them. 50% of patients experience a recurrent 2nd episode within 5 years. Of these 24% undergo a complete evaluation, 18% are referred to a nephrologist and 13.8% are prescribed medical therapy. 30% remain adherent to this pharmacotherapy. Of patients that are adherent 27% have lower odds of an ER visit than non-adherent patients. The cascade of care demonstrates that a low prevalence of patients receive proper followup. The impediments to the care of patients with kidney stones are (1) the unrecognized comorbidities of stones (2) disconnect between the ER and stone experts and (3) the low prevalence of 24h urine collections and prescribed medical therapy.
Conclusion(s): It is important to identify loci in the cascade of care that could represent opportunities to change practice. Prescription of appropriate fluid therapy and dietary changes and a referral to an expert should 1st be initiated by the ER. The low prevalence of 24h urine collections may reflect that the data are intimidating for some. Empiric therapy for calcium stones with fluids, diet, thiazides and potassium citrate may be a rational therapy to achieve significant supersaturation reductions and could be compared with targeted medical therapy in a randomized controlled trial. A greater effort needs to be devoted to develp a comprehensive flow of participants to retain patients in the cascade of care for USD. (Table Presented)

IN BRIEF Dietary guidelines for patients with diabetes extend beyond glycemic management to include recommendations for mitigating chronic disease risk. This review summarizes the literature suggesting that excess dietary phosphorus intake may increase the risk of skeletal and cardiovascular disease in patients who are in the early stages of chronic kidney disease (CKD) despite having normal serum phosphorus concentrations. It explores strategies for limiting dietary phosphorus, emphasizing that food additives, as a major source of highly bioavailable dietary phosphorus, may be a suitable target. Although the evidence for restricting phosphorus-based food additives in early CKD is limited, diabetes clinicians should monitor ongoing research aimed at assessing its efficacy.

Each year approximately 13,000 Veterans transition to maintenance dialysis, mostly in the traditional form of thrice-weekly hemodialysis from the start. Among >6000 dialysis units nationwide, there are currently approximately 70 Veterans Affairs (VA) dialysis centers. Given this number of VA dialysis centers and their limited capacity, only 10% of all incident dialysis Veterans initiate treatment in a VA center. Evidence suggests that, among Veterans, the receipt of care within the VA system is associated with favorable outcomes, potentially because of the enhanced access to healthcare resources. Data from the United States Renal Data System Special Study Center "Transition-of-Care-in-CKD" suggest that Veterans who receive dialysis in a VA unit exhibit greater survival compared with the non-VA centers. Substantial financial expenditures arise from the high volume of outsourced care and higher dialysis reimbursement paid by the VA than by Medicare to outsourced providers. Given the exceedingly high mortality and abrupt decline in residual kidney function (RKF) in the first dialysis year, it is possible that incremental transition to dialysis through an initial twice-weekly hemodialysis regimen might preserve RKF, prolong vascular access longevity, improve patients' quality of life, and be a more patient-centered approach, more consistent with "personalized" dialysis. Broad implementation of incremental dialysis might also result in more Veterans receiving care within a VA dialysis unit. Controlled trials are needed to examine the safety and efficacy of incremental hemodialysis in Veterans and other populations; the administrative and health care as well as provider structure within the VA system would facilitate the performance of such trials.