Vitamin D supplementation in children and young adults with persistent proteinuria secondary to glomerular disease.

BACKGROUND: Vitamin D deficiency is common in glomerular disease. Supplementation may be ineffective due to ongoing urinary losses of vitamin D binding protein. We sought to determine if daily cholecalciferol supplementation would increase vitamin D concentrations in children with glomerular disease and persistent proteinuria, without adverse effects. METHODS: Eighteen participants at least 5 years of age with primary glomerular disease and urine protein:creatinine ratio ≥ 0.5 were enrolled from four pediatric nephrology practices to receive cholecalciferol supplementation: 4,000 IU or 2,000 IU per day for serum 25 hydroxyvitamin vitamin D (25OHD) concentrations < 20 ng/mL and 20 ng/mL to < 30 ng/mL, respectively. Measures of vitamin D and mineral metabolism were obtained at baseline and weeks 6 and 12. Multivariable generalized estimating equation (GEE) regression estimated mean percent changes in serum 25OHD concentration. RESULTS: Median baseline 25OHD was 12.8 ng/mL (IQR 9.3, 18.9) and increased to 27.8 ng/mL (20.5, 36.0) at week 6 (p < 0.001) without further significant increase at week 12. A total of 31% of participants had a level ≥ 30 ng/mL at week 12. Supplementation was stopped in two participants at week 6 for mildly elevated calcium and phosphorus, respectively, with subsequent declines in 25OHD of > 20 ng/mL. In the adjusted GEE model, 25OHD was 102% (95% CI: 64, 141) and 96% (95% CI: 51, 140) higher versus baseline at weeks 6 and 12, respectively (p < 0.001). CONCLUSION: Cholecalciferol supplementation in vitamin D deficient children with glomerular disease and persistent proteinuria safely increases 25OHD concentration. Ideal dosing to fully replete 25OHD concentrations in this population remains unknown. CLINICAL TRIAL: NCT01835639. A higher resolution version of the Graphical abstract is available as Supplementary information.

A review of ferric citrate clinical studies, and the rationale and design of the Ferric Citrate and Chronic Kidney Disease in Children (FIT4KiD) trial.

Pediatric chronic kidney disease (CKD) is characterized by many co-morbidities, including impaired growth and development, CKD-mineral and bone disorder, anemia, dysregulated iron metabolism, and cardiovascular disease. In pediatric CKD cohorts, higher circulating concentrations of fibroblast growth factor 23 (FGF23) are associated with some of these adverse clinical outcomes, including CKD progression and left ventricular hypertrophy. It is hypothesized that lowering FGF23 levels will reduce the risk of these events and improve clinical outcomes. Reducing FGF23 levels in CKD may be accomplished by targeting two key stimuli of FGF23 production-dietary phosphate absorption and iron deficiency. Ferric citrate is approved for use as an enteral phosphate binder and iron replacement product in adults with CKD. Clinical trials in adult CKD cohorts have also demonstrated that ferric citrate decreases circulating FGF23 concentrations. This review outlines the possible deleterious effects of excess FGF23 in CKD, summarizes data from the adult CKD clinical trials of ferric citrate, and presents the Ferric Citrate and Chronic Kidney Disease in Children (FIT4KiD) study, a randomized, placebo-controlled trial to evaluate the effects of ferric citrate on FGF23 in pediatric patients with CKD stages 3-4 (ClinicalTrials.gov Identifier NCT04741646).

Novel genetic testing model: A collaboration between genetic counselors and nephrology.

Many barriers to genetic testing currently exist which delay or prevent diagnosis. These barriers include wait times, staffing, education, and cost. Specialists are able to identify patients with disease that may need genetic testing, but lack the genetics support to facilitate that testing in the most cost, time, and medically effective manner. The Nephrology Division and the Genetic Testing Stewardship Program at Nemours A.I. duPont Hospital for Children created a novel service delivery model in which nephrologists and genetic counselors collaborate in order to highlight their complementary strengths (clinical expertise of nephrologists and genetics and counseling skills of genetic counselors). This collaboration has reduced many barriers to care for our patients. This workflow facilitated the offering of genetic testing to 76 patients, with 86 tests completed over a 20-month period. Thirty-two tests were deferred. Twenty-seven patients received a diagnosis, which lead to a change in their medical management, three of whom were diagnosed by cascade family testing. Forty-two patients had a negative result and 16 patients had one or more variants of uncertain significance on testing. The inclusion of genetic counselors in the workflow is integral toward choosing the most cost and time effective genetic testing strategy, as well as providing psychosocial support to families. The genetic counselors obtain informed consent, and review genetic test results and recommendations with the patient and their family. The availability of this program to our patients increased access to genetic testing and helps to provide diagnoses and supportive care.

Using Electronic Health Record Data to Rapidly Identify Children with Glomerular Disease for Clinical Research.

BACKGROUND: The rarity of pediatric glomerular disease makes it difficult to identify sufficient numbers of participants for clinical trials. This leaves limited data to guide improvements in care for these patients. METHODS: The authors developed and tested an electronic health record (EHR) algorithm to identify children with glomerular disease. We used EHR data from 231 patients with glomerular disorders at a single center to develop a computerized algorithm comprising diagnosis, kidney biopsy, and transplant procedure codes. The algorithm was tested using PEDSnet, a national network of eight children's hospitals with data on >6.5 million children. Patients with three or more nephrologist encounters (n=55,560) not meeting the computable phenotype definition of glomerular disease were defined as nonglomerular cases. A reviewer blinded to case status used a standardized form to review random samples of cases (n=800) and nonglomerular cases (n=798). RESULTS: The final algorithm consisted of two or more diagnosis codes from a qualifying list or one diagnosis code and a pretransplant biopsy. Performance characteristics among the population with three or more nephrology encounters were sensitivity, 96% (95% CI, 94% to 97%); specificity, 93% (95% CI, 91% to 94%); positive predictive value (PPV), 89% (95% CI, 86% to 91%); negative predictive value, 97% (95% CI, 96% to 98%); and area under the receiver operating characteristics curve, 94% (95% CI, 93% to 95%). Requiring that the sum of nephrotic syndrome diagnosis codes exceed that of glomerulonephritis codes identified children with nephrotic syndrome or biopsy-based minimal change nephropathy, FSGS, or membranous nephropathy, with 94% sensitivity and 92% PPV. The algorithm identified 6657 children with glomerular disease across PEDSnet, ≥50% of whom were seen within 18 months. CONCLUSIONS: The authors developed an EHR-based algorithm and demonstrated that it had excellent classification accuracy across PEDSnet. This tool may enable faster identification of cohorts of pediatric patients with glomerular disease for observational or prospective studies.

LDL-apheresis-induced remission of focal segmental glomerulosclerosis recurrence in pediatric renal transplant recipients.

BACKGROUND: Focal segmental glomerulosclerosis (FSGS) in pediatric patients is typically difficult to treat and will progress to end-stage renal disease (ESRD) in about 10% of cases. Following kidney transplantation, FSGS can recur in up to 56% of renal allografts-with a near 100% recurrence in subsequent transplants. METHODS: Four different pediatric centers across the USA and the UK employed a protocol using LDL-apheresis (LDL-A) and pulse solumedrol to treat recurrent FSGS after transplantation in seven patients. All the patients included in this series demonstrated immediate, or early, recurrence of FSGS, which clinically presented as nephrotic-range proteinuria within hours to days after implantation of the kidney. RESULTS: All patients experienced reductions in urinary protein to creatinine ratios resulting in partial or complete remission. All patients demonstrated improvements in their estimated GFRs at their most recent follow-up since LDL-A discontinuation. CONCLUSIONS: This case series describes the successful treatment, across four different pediatric centers, of seven pediatric patients with recurrent post-transplant FSGS using the Liposorber® LA-15 in combination with pulse solumedrol.

Pharmacokinetics of ferric pyrophosphate citrate administered via dialysate and intravenously to pediatric patients on chronic hemodialysis.

BACKGROUND: Iron deficiency is a common cause of anemia in pediatric patients with hemodialysis-dependent chronic kidney disease (CKD-5HD). Ferric pyrophosphate citrate (FPC, Triferic®) donates iron directly to transferrin, bypassing the reticuloendothelial system and avoiding iron sequestration. Administration of FPC via dialysate or intravenously (IV) may provide a suitable therapeutic option to current IV iron preparations for these patients. METHODS: The pharmacokinetics and safety of FPC administered via dialysate and IV to patients aged < 6 years (n = 3), 6 to < 12 years (n = 4), and 12 to <18 years (n = 15) were investigated in a multicenter, open-label, two-period, single-dose study. FPC (0.07 mg iron/kg) was infused IV into the venous blood return line during hemodialysis session no. 1. FPC iron was added to bicarbonate concentrate to deliver 2 µM (110 µg/L) iron via dialysate during hemodialysis session no. 2. RESULTS: Mean serum total iron concentrations peaked 3 to 4 h after administration via dialysate and 2 to 4 h after IV administration and returned to baseline by 10 h after the start of hemodialysis for both routes. Iron exposure was greater after administration via dialysate than after IV administration. The absolute amount of absorbed iron after administration via dialysate roughly doubled with increasing age, but the weight-normalized amount of absorbed iron was relatively constant across age groups (~ 0.06-0.10 mg/kg). FPC was well tolerated in the small number of patients studied. CONCLUSIONS: FPC iron can be administered to pediatric patients with CKD-5HD via dialysate or by the IV route. Further study of FPC administered to maintain hemoglobin concentration is indicated.

The use of renal replacement therapy in critically ill pediatric small bowel transplantation candidates and recipients: Experience from one center.

Outcomes for pediatric SBT patients requiring perioperative RRT in the PICU remain unknown. The objectives were to document our center's experience with PICU SBT patients receiving perioperative RRT and to identify variables predictive of survival to discharge. A retrospective chart review of patients (ages, 0-18 yr) between January 1, 2000 and December 31, 2011 that received RRT within a SBT perioperative period and were transplanted at our university-affiliated, tertiary care children's hospital was performed. Six SBT patients received perioperative RRT (ages, 5-12 yr). Three patients (50%) survived to hospital discharge. Among survivors, RRT was required for a total of 1-112 days (mean, 49.7 days). All three survivors survived to hospital discharge without renal transplantation and free of RRT. There was a trend toward increased survival among older patients receiving RRT (p = 0.05). Survivors had a higher I-125 GFR prior to PICU admission (p = 0.045). A higher I-125 GFR prior to PICU admission among survivors may support this test's utility during SBT evaluation. In our experience, a high survival rate and freedom from RRT at the time of discharge support RRT use in the SBT population.

Suppression of iron-regulatory hepcidin by vitamin D.

The antibacterial protein hepcidin regulates the absorption, tissue distribution, and extracellular concentration of iron by suppressing ferroportin-mediated export of cellular iron. In CKD, elevated hepcidin and vitamin D deficiency are associated with anemia. Therefore, we explored a possible role for vitamin D in iron homeostasis. Treatment of cultured hepatocytes or monocytes with prohormone 25-hydroxyvitamin D or active 1,25-dihydroxyvitamin D decreased expression of hepcidin mRNA by 0.5-fold, contrasting the stimulatory effect of 25-hydroxyvitamin D or 1,25-dihydroxyvitamin D on related antibacterial proteins such as cathelicidin. Promoter-reporter and chromatin immunoprecipitation analyses indicated that direct transcriptional suppression of hepcidin gene (HAMP) expression mediated by 1,25-dihydroxyvitamin D binding to the vitamin D receptor caused the decrease in hepcidin mRNA levels. Suppression of HAMP expression was associated with a concomitant increase in expression of the cellular target for hepcidin, ferroportin protein, and decreased expression of the intracellular iron marker ferritin. In a pilot study with healthy volunteers, supplementation with a single oral dose of vitamin D (100,000 IU vitamin D2) increased serum levels of 25D-hydroxyvitamin D from 27±2 ng/ml before supplementation to 44±3 ng/ml after supplementation (P<0.001). This response was associated with a 34% decrease in circulating levels of hepcidin within 24 hours of vitamin D supplementation (P<0.05). These data show that vitamin D is a potent regulator of the hepcidin-ferroportin axis in humans and highlight a potential new strategy for the management of anemia in patients with low vitamin D and/or CKD.

Review of childhood genetic nephrolithiasis and nephrocalcinosis.

Nephrolithiasis (NL) is a common condition worldwide. The incidence of NL and nephrocalcinosis (NC) has been increasing, along with their associated morbidity and economic burden. The etiology of NL and NC is multifactorial and includes both environmental components and genetic components, with multiple studies showing high heritability. Causative gene variants have been detected in up to 32% of children with NL and NC. Children with NL and NC are genotypically heterogenous, but often phenotypically relatively homogenous, and there are subsequently little data on the predictors of genetic childhood NL and NC. Most genetic diseases associated with NL and NC are secondary to hypercalciuria, including those secondary to hypercalcemia, renal phosphate wasting, renal magnesium wasting, distal renal tubular acidosis (RTA), proximal tubulopathies, mixed or variable tubulopathies, Bartter syndrome, hyperaldosteronism and pseudohyperaldosteronism, and hyperparathyroidism and hypoparathyroidism. The remaining minority of genetic diseases associated with NL and NC are secondary to hyperoxaluria, cystinuria, hyperuricosuria, xanthinuria, other metabolic disorders, and multifactorial etiologies. Genome-wide association studies (GWAS) in adults have identified multiple polygenic traits associated with NL and NC, often involving genes that are involved in calcium, phosphorus, magnesium, and vitamin D homeostasis. Compared to adults, there is a relative paucity of studies in children with NL and NC. This review aims to focus on the genetic component of NL and NC in children.

Prospective Study of the Multisite Spread of a Medication Safety Intervention: Factors Common to Hospitals With Improved Outcomes.

Context and implementation approaches can impede the spread of patient safety interventions. The objective of this article is to characterize factors associated with improved outcomes among 9 hospitals implementing a medication safety intervention. Nephrotoxic Injury Negated by Just-in-Time Action (NINJA) is a pharmacist-driven intervention that led to a sustained reduction in nephrotoxic medication-associated acute kidney injury (NTMx-AKI) at 1 hospital. Using qualitative comparative analysis, the team prospectively assessed the association between context and implementation factors and NTMx-AKI reduction during NINJA spread to 9 hospitals. Five hospitals reduced NTMx-AKI. These 5 had either (1) a pharmacist champion and >2 pharmacists working on NINJA (Scon 1.0, Scov 0.8) or (2) a nephrologist-implementing NINJA with minimal competing organizational priorities (Scon 1.0, Scov 0.2). Interviews identified ways NINJA team leaders obtained pharmacist support or successfully implemented without that support. In conclusion, these findings have implications for future spread of NINJA and suggest an approach to study spread of safety interventions more broadly.

Correlates of parathyroid hormone concentration in hemodialysis patients.

BACKGROUND: The implications of chemical hyperparathyroidism on bone and mineral metabolism measures in maintenance hemodialysis (MHD) are not well known. We hypothesized that a higher serum intact parathyroid hormone (iPTH) level is associated with the higher likelihood of hyperphosphatemia, hyperphosphatasemia [high serum alkaline phosphatase (ALP) levels] and hypercalcemia. METHODS: Over an 8-year period (July 2001-June 2009), we identified 106 760 MHD patients with iPTH and calcium (Ca), phosphorous (P) and ALP data from a large dialysis clinic. Logistic regression models were examined to assess the association between serum iPTH increments and the likelihood of hyperphosphatemia (P ≥5.5 mg/dL), hypercalcemia (Ca ≥10.2 mg/dL) and hyperphosphatasemia (ALP ≥120 U/L). RESULTS: Patients were 61 ± 16 years old and included 45% women, 59% diabetics and 33% Blacks. Compared with an iPTH level of 100 to <200 pg/mL, patients with an iPTH level of 600-700, 700 to <800 and ≥800 pg/mL had 122% (OR: 2.22, 95% CI: 2.04-2.41), 153% (OR: 2.53, 95% CI: 2.29-2.80) and 243% (OR: 3.43, 95% CI: 3.22-3.66) higher risk of hyperphosphatemia, respectively, and had 109% (OR: 2.09, 95% CI: 1.93-2.26), 130% (OR: 2.30, 95% CI: 2.10-2.52) and 376% (OR: 4.76, 95% CI: 4.50-5.04) higher risk of hyperphosphatasemia, respectively. Compared with an iPTH level of 100 to <200 pg/mL, both the low iPTH (<100 pg/mL, OR: 2.45, 95% CI: 2.27-2.64) and the high iPTH (≥800 pg/mL: OR: 2.13, 95% CI: 1.95-2.33) levels were associated with hypercalcemia. CONCLUSIONS: Higher levels of iPTH are incremental correlates of hyperphosphatemia and hyperphosphatasemia, whereas both very low and high PTH levels are linked to hypercalcemia. If these associations are causal, correction of hyperparathyroidism may have overarching implications on bone and mineral disorders in MHD patients.

Association of malnutrition-inflammation complex and responsiveness to erythropoiesis-stimulating agents in long-term hemodialysis patients.

BACKGROUND: Protein-energy wasting, inflammation and refractory anemia are common in long-term hemodialysis patients. A decreased responsiveness to erythropoiesis-stimulating agents (ESA) is often the cause of the refractory anemia. We hypothesized that the malnutrition-inflammation complex is an independent predictor of decreased responsiveness to ESAs in hemodialysis patients. METHODS: This cohort study of 754 hemodialysis patients was examined for an association between inflammatory and nutritional markers, including the malnutrition-inflammation score (MIS) and responsiveness to ESA. Cubic spline models were fitted to verify found associations. RESULTS: The mean (±SD) age of patients was 54 ± 15 years, 53% were diabetic and 32% blacks. MIS was worse in the highest quartile of ESAs responsiveness index (ERI, ESA dose divided by hemoglobin) when compared with 1st quartile (6.5 ± 4.5 versus 4.4 ± 3.4; P < 0.001). Both C-reactive protein (log CRP) (ß = 0.19) and interleukin-6 (log IL-6) (ß = 0.32) were strong and independent predictors of ERI using multivariate linear regression. Serum albumin (ß = -0.30) and prealbumin levels (ß = -0.14) were inversely associated with ERI. Each 1 SD higher MIS, higher CRP and lower albumin were associated with 86, 44 and 97% higher likelihood of having highest versus three lowest ERI quartiles in fully adjusted models [odds ratio (and 95% confidence interval) of 1.86 (1.31-2.85), 1.44 (1.08-1.92) and 1.97 (1.41-2.78)], respectively. Cubic splines confirmed the continuous and incremental nature of these associations. CONCLUSIONS: Malnutrition-inflammation complex is an incremental predictor of poor responsiveness to ESAs in hemodialysis patients. Further studies are needed to assess whether modulating inflammatory or nutritional processes can improve anemia management.

Mortality associated with dose response of erythropoiesis-stimulating agents in hemodialysis versus peritoneal dialysis patients.

BACKGROUND: Several studies have shown an association between erythropoietin-stimulating agent (ESA) responsiveness and mortality in chronic kidney disease (CKD) patients. In our present study, we examined the association between prescribed ESA dose and mortality in peritoneal dialysis (PD) and hemodialysis (HD) patients. We hypothesized that PD patients received lower ESA dose for the same achieved hemoglobin compared to HD patients and that ESA dose-mortality associations were different between PD and HD patients. METHODS: We compared the prescribed doses of ESA between 139,103 HD and 10,527 PD patients treated in DaVita dialysis clinics from 7/2001 through 6/2006 using adjusted Poisson regression and examined mortality-predictability of prescribed ESA dose and ESA responsiveness index (ESA/hemoglobin) in PD and HD with follow-up through 6/2007 using Cox regression models. RESULTS: Poisson adjusted ratio of ESA dose of HD to PD was 3.6 (95% CI 3.5-3.7). In PD patients, adjusted all-cause death hazard ratios (HR) for ESA doses of 3,000-5,999, 6,000-8,999 and ≥9,000 U/week (reference <3,000 U/week) were 0.97 (0.87-1.07), 0.85 (0.76-0.95) and 1.08 (0.98-1.18), respectively; whereas in HD patients across commensurate ESA dose increments of 10,000-19,999, 20,000-29,999 and ≥30,000 U/week (reference <10,000 U/week) were 1.14 (1.11-1.17), 1.54 (1.50-1.58) and 2.15 (2.10-2.21), respectively. In PD and HD patients, the adjusted death HR of the 4th to 1st quartile of ESA responsiveness index were 1.14 (1.04-1.26) and 2.37 (2.31-2.43), respectively. CONCLUSIONS: Between 2001 and 2006, most PD patients received substantially lower ESA dose for same achieved hemoglobin levels, and low ESA responsiveness was associated with higher mortality in both HD and PD patients.

Mineral and bone disorders and survival in hemodialysis patients with and without polycystic kidney disease.

BACKGROUND: Maintenance hemodialysis (MHD) patients with polycystic kidney disease (PKD) have better survival than non-PKD patients. Mineral and bone disorders (MBD) are associated with accelerated atherosclerosis and cardiovascular death in MHD patients. It is unknown whether the different MBD mortality association between MHD populations with and without PKD can explain the survival differential. METHODS: Survival models were examined to assess the association between different laboratory markers of MBD [such as serum phosphorous, parathyroid hormone (PTH), calcium and alkaline phosphatase] and mortality in a 6-year cohort of 60,089 non-PKD and 1501 PKD MHD patients. RESULTS: PKD and non-PKD patients were 57±13 and 62±15 years old and included 46 and 45% women and 14 and 32% Blacks, respectively. Whereas PKD individuals with PTH 150 to <300 pg/mL (reference) had the lowest risk for mortality, the death risk was higher in patients with PTH<150 [hazard ratio (HR): 2.16 (95% confidence interval 1.53-3.06)], 300 to <600 [HR: 1.30 (0.97-1.74)] and ≥600 pg/mL [HR: 1.46 (1.02-2.08)], respectively. Similar patterns were found in non-PKD patients. Fully adjusted death HRs of time-averaged serum phosphorous increments<3.5, 5.5 to <7.5 and ≥7.5 mg/dL (reference: 3.5 to <5.5 mg/dL) for PKD patients were 2.82 (1.50-5.29), 1.40 (1.12-1.75) and 2.25 (1.57-3.22). The associations of alkaline phosphatase and calcium with mortality were similar in PKD and non-PKD patients. CONCLUSION: Bone-mineral disorder markers exhibit similar mortality trends between PKD and non-PKD MHD patients, although some differences are observed in particular in low PTH and phosphorus ranges.

Hemoglobin level and survival in hemodialysis patients with polycystic kidney disease and the role of administered erythropoietin.

Interventional trials indicate adverse outcomes when hemoglobin >13 g/dL is targeted in patients with chronic kidney disease (CKD) who receive erythropoiesis-stimulating agents (ESAs). It is not clear whether high-achieved hemoglobin with minimal to no ESA administration as observed in some patients with polycystic kidney disease (PKD) is also associated with poor outcomes. Survival models were examined to assess the association between hemoglobin increments and mortality in a 6-year cohort of 2,402 PKD and 110,875 non-PKD hemodialysis patients across infrequent versus frequent ESA therapy defined as ESA < 25% of cohort time versus otherwise, respectively. Mortality risk was estimated by Cox proportional regression [hazard ratio (HR) and 95% of confidence interval] analysis. Patients with PKD were aged 58 ± 13 years and included 46% women 14% Blacks, respectively. Fully adjusted death HRs of time-averaged hemoglobin increments <11.0, 12.0 to <13.0 g/dL (reference: 11.0 to <12.0 g/dL) for frequent ESA therapy were 2.57 (1.48-4.48), 0.60 (0.43-0.82), and 0.81 (0.50-1.29), whereas for infrequent ESA therapy they were 1.33 (0.47-3.78), 0.28 (0.13-0.61), and 0.22 (0.09-0.57), respectively. Hence, in patients with PKD who require infrequent ESA, incrementally higher achieved hemoglobin including > 13.0 g/dL exhibits better survival; this incremental survival gain of higher hemoglobin is not observed in patients with PKD receiving frequent ESA administration, in whom hemoglobin concentration > 13 exhibits increased mortality.

Administered paricalcitol dose and survival in hemodialysis patients: a marginal structural model analysis.

PURPOSE: Several observational studies have indicated that vitamin D receptor activators (VDRA), including paricalcitol, are associated with greater survival in maintenance hemodialysis (MHD) patients. However, patients with higher serum parathyroid hormone, a surrogate of higher death risk, are usually given higher VDRA doses, which can lead to confounding by indication and attenuate the expected survival advantage of high VDRA doses. METHODS: We examined mortality-predictability of low (>1 but <10 µg/week) versus high (≥10 µg/week) dose of administered paricalcitol over time in a contemporary cohort of 15 442 MHD patients (age 64 ± 15 years, 55% men, 44% diabetes, 35% African-Americans) from all DaVita dialysis clinics across the USA (7/2001-6/2006 with survival follow-ups until 6/2007) using conventional Cox regression, propensity score (PS) matching, and marginal structural model (MSM) analyses. RESULTS: In our conventional Cox models and PS matching models, low dose of paricalcitol was not associated with mortality either in baseline (hazard ratio (HR): 1.03, 95% confidence interval (CI): (0.97-1.09)) and (HR: 0.99, 95%CI:(0.86-1.14)) or time-dependent (HR: 1.04, 95%CI: (0.98-1.10)) and (HR: 1.12, 95%CI: (0.98-1.28)) models, respectively. In contrast, compared to high dose of paricalcitol, low dose was associated with a 26% higher risk of mortality (HR: 1.26, 95%CI: (1.19-1.35)) in MSM. The association between dose of paricalcitol and mortality was robust in almost all subgroups of patients using MSMs. CONCLUSIONS: Higher dose of paricalcitol appears causally associated with greater survival in MHD patients. Randomized controlled trials need to verify the survival effect of paricalcitol dose in MHD patients are indicated.

Ironing out the phosphorus problem.

Control of serum phosphorus remains a vexing problem in chronic kidney disease. Although novel dialysis regimens may provide excellent phosphorus control, phosphate binders remain necessary for most dialysis patients. Block et al. present a phase I clinical trial examining the safety and efficacy of SBR759, a novel non-calcium, iron-based phosphate binder. Although the risks of iron accumulation and hypocalcemia must be addressed, this phosphate binder appears to be well tolerated and effective and offers a powder-based formulation.

Successful treatment of calcific uremic arteriolopathy in a pediatric dialysis patient.

Calcific uremic arteriolopathy (CUA) is a rare, life-threatening disease, typically affecting patients with end-stage renal disease. It is characterized by widespread vascular calcification, endothelial fibrosis and end-organ ischemia. The mortality rate is high with infection and sepsis being the most common causes of death. Common therapies include restoration of calcium and phosphorous homeostasis, wound care and pain control. Although soft tissue calcification is a known complication in children with advanced renal disease, the incidence of CUA in pediatrics remains unknown. Additionally, current literature regarding its management in pediatric patients is lacking. We report the case of a 17-year-old African-American male patient with end-stage renal disease secondary to Wegener's granulomatosis who developed CUA after 3 years on peritoneal dialysis. Treatment with sodium thiosulfate (STS) and hyperbaric oxygen (HBO) therapy alone was ineffective, forcing the patient to undergo bilateral below the-knee-amputation (BKA) 5 months after presentation. It was not until peritoneal dialysis had been changed to daily hemodialysis, while continuing STS and HBO therapy, that the patient demonstrated complete resolution of CUA on repeat bone scan. Based on these findings, and the extremely high mortality rate associated with this disease, CUA management requires early and aggressive intervention with multi-faceted therapy, including prompt conversion from peritoneal dialysis to hemodialysis, STS infusions and hyperbaric oxygen therapy.

Dyslipidaemia in nephrotic syndrome: mechanisms and treatment.

Nephrotic syndrome is a highly prevalent disease that is associated with high morbidity despite notable advances in its treatment. Many of the complications of nephrotic syndrome, including the increased risk of atherosclerosis and thromboembolism, can be linked to dysregulated lipid metabolism and dyslipidaemia. These abnormalities include elevated plasma levels of cholesterol, triglycerides and the apolipoprotein B-containing lipoproteins VLDL and IDL; decreased lipoprotein lipase activity in the endothelium, muscle and adipose tissues; decreased hepatic lipase activity; and increased levels of the enzyme PCSK9. In addition, there is an increase in the plasma levels of immature HDL particles and reduced cholesterol efflux. Studies from the past few years have markedly improved our understanding of the molecular pathogenesis of nephrotic syndrome-associated dyslipidaemia, and also heightened our awareness of the associated exacerbated risks of cardiovascular complications, progressive kidney disease and thromboembolism. Despite the absence of clear guidelines regarding treatment, various strategies are being increasingly utilized, including statins, bile acid sequestrants, fibrates, nicotinic acid and ezetimibe, as well as lipid apheresis, which seem to also induce partial or complete clinical remission of nephrotic syndrome in a substantial percentage of patients. Future potential treatments will likely also include inhibition of PCSK9 using recently-developed anti-PCSK9 monoclonal antibodies and small inhibitory RNAs, as well as targeting newly identified molecular regulators of lipid metabolism that are dysregulated in nephrotic syndrome.