Sugar, salt, immunity and the cause of primary hypertension.

Despite its discovery more than 150 years ago, the cause of primary hypertension remains unknown. Most studies suggest that hypertension involves genetic, congenital or acquired risk factors that result in a relative inability of the kidney to excrete salt (sodium chloride) in the kidneys. Here we review recent studies that suggest there may be two phases, with an initial phase driven by renal vasoconstriction that causes low-grade ischemia to the kidney, followed by the infiltration of immune cells that leads to a local autoimmune reaction that maintains the renal vasoconstriction. Evidence suggests that multiple mechanisms could trigger the initial renal vasoconstriction, but one way may involve fructose that is provided in the diet (such as from table sugar or high fructose corn syrup) or produced endogenously. The fructose metabolism increases intracellular uric acid, which recruits NADPH oxidase to the mitochondria while inhibiting AMP-activated protein kinase. A drop in intracellular ATP level occurs, triggering a survival response. Leptin levels rise, triggering activation of the sympathetic central nervous system, while vasopressin levels rise, causing vasoconstriction in its own right and stimulating aldosterone production via the vasopressin 1b receptor. Low-grade renal injury and autoimmune-mediated inflammation occur. High-salt diets can amplify this process by raising osmolality and triggering more fructose production. Thus, primary hypertension may result from the overactivation of a survival response triggered by fructose metabolism. Restricting salt and sugar and hydrating with ample water may be helpful in the prevention of primary hypertension.

Genetic testing in children with nephrolithiasis and nephrocalcinosis.

BACKGROUND: Diagnosing genetic kidney disease has become more accessible with low-cost, rapid genetic testing. The study objectives were to determine genetic testing diagnostic yield and examine predictors of genetic diagnosis in children with nephrolithiasis/nephrocalcinosis (NL/NC). METHODS: This retrospective multicenter cross-sectional study was conducted on children ≤ 21 years old with NL/NC from pediatric nephrology/urology centers that underwent the Invitae Nephrolithiasis Panel 1/1/2019-9/30/2021. The diagnostic yield of the genetic panel was calculated. Bivariate and multiple logistic regression were performed to assess for predictors of positive genetic testing. RESULTS: One hundred and thirteen children (83 NL, 30 NC) from 7 centers were included. Genetic testing was positive in 32% overall (29% NL, 40% NC) with definite diagnoses (had pathogenic variants alone) made in 11.5%, probable diagnoses (carried a combination of pathogenic variants and variants of uncertain significance (VUS) in the same gene) made in 5.4%, and possible diagnoses (had VUS alone) made in 15.0%. Variants were found in 28 genes (most commonly HOGA1 in NL, SLC34A3 in NC) and 20 different conditions were identified. Compared to NL, those with NC were younger and had a higher proportion with developmental delay, hypercalcemia, low serum bicarbonate, hypophosphatemia, and chronic kidney disease. In multivariate analysis, low serum bicarbonate was associated with increased odds of genetic diagnosis (ß 2.2, OR 8.7, 95% CI 1.4-54.7, p = 0.02). CONCLUSIONS: Genetic testing was high-yield with definite, probable, or possible explanatory variants found in up to one-third of children with NL/NC and shows promise to improve clinical practice. A higher resolution version of the Graphical abstract is available as Supplementary information.

Adverse childhood experiences are associated with vascular changes in adolescents that are risk factors for future cardiovascular disease.

BACKGROUND: Adverse childhood experiences (ACEs), such as abuse, neglect, and household dysfunction, are associated with a higher risk of cardiovascular disease (CVD) and indicators of future CVD risk in adulthood, such as greater vascular stiffness. The impact of ACEs in adolescence is unclear, and understanding how ACEs relate to blood pressure (BP) and vascular function during early life is key for the development of prevention strategies to reduce CVD risk. We hypothesized that exposure to ACEs would be associated with changes in central hemodynamics such as increased vascular stiffness and higher BP during adolescence. METHODS: This pilot study enrolled 86 adolescents recruited from the Children's of Alabama. A validated ACE questionnaire was employed, and ACEs were modeled both as a continuous variable and a categorical variable (ACE ≥ 1 vs. ACE = 0). The primary outcomes used are considered to be indicators of future cardio-renal disease risk: aortic augmentation index normalized to 75 bpm (Alx75, a surrogate for vascular stiffness), carotid-femoral PWV (m/s), and ambulatory BP patterns. RESULTS: Adolescents with ACE ≥ 1 had significantly higher Alx75 (ACE: 5.2% ± 2.2 compared to no ACE: - 1.4% ± 3.0; p = 0.043). PWV only reflected this trend when adjustments were made for the body mass index. Adolescents with ACEs showed no differences in ambulatory BP patterns during the 24-h, wake, or sleep periods compared to adolescents with no ACEs. CONCLUSIONS: ACEs were associated with higher AIx75 in adolescence, which is a risk factor for future CVD. Adolescence could present an opportunity for early detections/interventions to mitigate adverse cardiovascular outcomes in adulthood. A higher resolution version of the Graphical abstract is available as Supplementary information.

Kidney implications of SARS-CoV2 infection in children.

Research indicates that severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection can impact every organ, and the effects can range from asymptomatic to severe disease. Since it was first discovered in December 2019, our understanding has grown about its impact on kidney disease. In general, children have less severe disease than adults, and this tendency appears to extend to special pediatric kidney populations (e.g., chronic kidney disease and immunosuppressed patients with solid organ transplants or nephrotic syndrome). However, in a fraction of infected children, SARS-CoV2 causes an array of kidney manifestations, ranging from acute kidney injury to thrombotic microangiopathy, with potential implications for increased risk of morbidity and mortality. Additional considerations surround the propensity for clotting extracorporeal circuits in children with SARS-CoV2 infection that are receiving kidney replacement therapy. This review provides an update on our current understanding of SARS-CoV2 for pediatric nephrologists and highlights knowledge gaps to be addressed by future research during this ongoing pandemic, particularly the social disparities magnified during this period.

Trends in Blood Pressure and Hypertension Among US Children and Adolescents, 1999-2018.

Importance: Higher blood pressure (BP) levels in children are associated with an increased risk for hypertension and subclinical cardiovascular disease in adulthood. Identifying trends in BP could inform the need for interventions to lower BP. Objective: To determine whether systolic BP (SBP) and diastolic BP (DBP) levels among US children have changed during the past 20 years. Design, Setting, and Participants: This serial cross-sectional analysis of National Health and Nutrition Examination Survey data included 9117 children aged 8 to 12 years and 10 156 adolescents aged 13 to 17 years, weighted to the US population from 1999-2002 to 2015-2018. Data were collected from March 1999 to December 2018 and analyzed from March 26, 2020, to February 2, 2021. Exposures: Calendar year. Main Outcomes and Measures: The primary outcomes were mean SBP and mean DBP. Results: A total of 19 273 participants were included in the analysis. Among children aged 8 to 12 years in 2015-2018 (mean age, 10.5 [95% CI, 10.5-10.6] years), 48.7% (95% CI, 45.2%-52.2%) were girls and 51.3% (95% CI, 47.8%-54.8%) were boys; 49.7% (95% CI, 42.2%-57.1%) were non-Hispanic White; 13.7% (95% CI, 10.3%-18.1%) were non-Hispanic Black; 25.5% (95% CI, 19.9%-32.0%) were Hispanic; 4.7% (95% CI, 3.2%-6.7%) were non-Hispanic Asian; and 6.5% (95% CI, 4.9%-8.5%) were other non-Hispanic race/ethnicity. Among those aged 13 to 17 years in 2015-2018 (mean age, 15.5 [95% CI, 15.5-15.5] years), 49.1% (95% CI, 46.1%-52.2%) were girls and 50.9% (95% CI, 47.8%-53.9%) were boys; 53.3% (95% CI, 46.4%-60.1%) were non-Hispanic White; 13.9% (95% CI, 10.3%-18.7%) were non-Hispanic Black; 21.9% (95% CI, 16.6%-28.2%) were Hispanic; 4.6% (95% CI, 3.2%-6.5%) were non-Hispanic Asian; and 6.3% (95% CI, 4.7%-8.5%) were other non-Hispanic race/ethnicity. Among children aged 8 to 12 years, age-adjusted mean SBP decreased from 102.4 (95% CI, 101.7-103.1) mm Hg in 1999-2002 to 101.5 (95% CI, 100.8-102.2) mm Hg in 2011-2014 and then increased to 102.5 (95% CI, 101.9-103.2) mm Hg in 2015-2018. Age-adjusted mean DBP decreased from 57.2 (95% CI, 56.5-58.0) mm Hg in 1999-2002 to 51.9 (95% CI, 50.1-53.7) mm Hg in 2011-2014 and increased to 53.2 (95% CI, 52.2-54.1) mm Hg in 2015-2018. Among adolescents aged 13 to 17 years, age-adjusted mean SBP decreased from 109.2 (95% CI, 108.7-109.7) mm Hg in 1999-2002 to 108.4 (95% CI, 107.8-109.1) mm Hg in 2011-2014 and remained unchanged in 2015-2018 (108.4 [95% CI, 107.8-109.1] mm Hg). Mean DBP decreased from 62.6 (95% CI, 61.7-63.5) mm Hg in 1999-2002 to 59.6 (95% CI, 58.2-60.9) mm Hg in 2011-2014 and then increased to 60.8 (95% CI, 59.8-61.7) mm Hg in 2015-2018. Among children aged 8 to 12 years, mean SBP was 3.2 (95% CI, 1.7-4.6) mm Hg higher among those with overweight and 6.8 (95% CI, 5.6-8.1) mm Hg higher among those with obesity compared with normal weight; mean DBP was 3.2 (95% CI, 0.7-5.6) mm Hg higher among those with overweight and 3.5 (95% CI, 1.9- 5.1) mm Hg higher among those with obesity compared with normal weight. Among adolescents aged 13 to 17 years, mean SBP was 3.5 (95% CI 1.9-5.1) mm Hg higher among those with overweight and 6.6 (95% CI, 5.2-8.0) mm Hg higher among those with obesity compared with normal weight, 4.8 (95% CI, 3.8-5.8) mm Hg higher among boys compared with girls, and 3.0 (95% CI, 1.7-4.3) mm Hg higher among non-Hispanic Black compared with non-Hispanic White participants. Conclusions and Relevance: Despite an overall decline in mean SBP and DBP from 1999-2002 to 2015-2018, BP levels among children and adolescents may have increased from 2011-2014 to 2015-2018.

Effect of Serum Urate Lowering With Allopurinol on Blood Pressure in Young Adults: A Randomized, Controlled, Crossover Trial.

OBJECTIVE: To determine whether serum urate reduction with allopurinol lowers blood pressure (BP) in young adults and the mechanisms mediating this hypothesized effect. METHODS: We conducted a single-center, randomized, double-blind, crossover clinical trial. Adults ages 18-40 years with baseline systolic BP ≥120 and <160 mm Hg or diastolic BP ≥80 and <100 mm Hg, and serum urate ≥5.0 mg/dl for men or ≥4.0 mg/dl for women were enrolled. Main exclusion criteria included chronic kidney disease, gout, or past use of urate-lowering therapies. Participants received oral allopurinol (300 mg daily) or placebo for 1 month followed by a 2-4 week washout and then were crossed over. Study outcome measures were change in systolic BP from baseline, endothelial function estimated as flow-mediated dilation (FMD), and high-sensitivity C-reactive protein (hsCRP) levels. Adverse events were assessed. RESULTS: Ninety-nine participants were randomized, and 82 completed all visits. The mean ± SD age was 28.0 ± 7.0 years, 62.6% were men, and 40.4% were African American. In the primary intent-to-treat analysis, systolic BP did not change during the allopurinol treatment phase (mean ± SEM -1.39 ± 1.16 mm Hg) or placebo treatment phase (-1.06 ± 1.08 mm Hg). FMD increased during allopurinol treatment periods compared to placebo treatment periods (mean ± SEM 2.5 ± 0.55% versus -0.1 ± 0.42%; P < 0.001). There were no changes in hsCRP level and no serious adverse events. CONCLUSION: Our findings indicate that urate-lowering therapy with allopurinol does not lower systolic BP or hsCRP level in young adults when compared with placebo, despite improvements in FMD. These findings do not support urate lowering as a treatment for hypertension in young adults.

Hyperuricemia is associated with a lower glomerular filtration rate in pediatric sickle cell disease patients.

BACKGROUND: Sickle cell nephropathy (SCN) is a progressive disease that contributes significant morbidity and mortality in sickle cell disease (SCD), yet it remains poorly understood. Hyperuricemia negatively impacts renal function in the non-sickle cell population but is understudied in SCD. METHODS: We performed a cross-sectional analysis of the first 78 pediatric SCD patients enrolled in a cohort study. The mechanism of development of hyperuricemia (defined, serum uric acid (UA) ≥ 5.5 mg/dL) was characterized as a result of either UA overproduction or inefficient renal excretion by the Simkin index and fractional clearance of urate (FCU) equations. Associations between hyperuricemia and albuminuria or estimated glomerular filtration rate (eGFR) were determined by linear regression. RESULTS: The prevalence of hyperuricemia in this young population (mean age 11.6 ± 3.77 years) was 34.2%. Only 1 hyperuricemic participant overproduced UA by Simkin index, while 62.5% were inefficient renal excretors of UA (FCU < 4%). Hyperuricemia was associated with a significant decrease in average eGFR, -27 ml/min/1.73m2 below normouricemia (mean eGFR 151.6 ± 40.32), p = 0.0122. Notably, the previously accepted association between decline of eGFR with age is significantly modified by hyperuricemia stratification, where hyperuricemia explains 44% of the variance in eGFR by age (R2 = 0.44, p = 0.0004) and is nonsignificant in normouricemia (R2 = 0.07, p = 0.0775). CONCLUSION: These findings indicate that hyperuricemia may be associated with early eGFR decline in SCN. This association must be further characterized in prospective cohort studies in SCN, and hyperuricemia must be investigated as a potential therapeutic target for SCN.

The case for uric acid-lowering treatment in patients with hyperuricaemia and CKD.

Hyperuricaemia is common among patients with chronic kidney disease (CKD), and increases in severity with the deterioration of kidney function. Although existing guidelines for CKD management do not recommend testing for or treatment of hyperuricaemia in the absence of a diagnosis of gout or urate nephrolithiasis, an emerging body of evidence supports a direct causal relationship between serum urate levels and the development of CKD. Here, we review randomized clinical trials that have evaluated the effect of urate-lowering therapy (ULT) on the rate of CKD progression. Among trials in which individuals in the control arm experienced progressive deterioration of kidney function (which we define as ≥4 ml/min/1.73 m² over the course of the study - typically 6 months to 2 years), treatment with ULT conferred consistent clinical benefits. In contrast, among trials where clinical progression was not observed in the control arm, treatment with ULT was ineffective, but this finding should not be used as an argument against the use of uric acid-lowering therapy. Although additional studies are needed to identify threshold values of serum urate for treatment initiation and to confirm optimal target levels, we believe that sufficient evidence exists to recommend routine measurement of serum urate levels in patients with CKD and consider initiation of ULT among those who are hyperuricaemic with evidence of deteriorating renal function, unless specific contraindications exist.

CYP3A5 genotype affects time to therapeutic tacrolimus level in pediatric kidney transplant recipients.

BACKGROUND: Optimal management of immunosuppression in kidney transplantation requires a delicate balance of efficacy and toxicity. Tacrolimus (TAC) dose requirements are significantly impacted by genetic variation in CYP3A5 polymorphisms, however the impact that genotype has on clinical outcomes in the pediatric kidney transplant population remains unclear. METHODS: We evaluated a retrospective cohort of 98 pediatric kidney transplant recipients. The primary exposure was CYP3A5 genotype, which classified each recipient into the expresser (at least one CYP3A5*1 allele) or non-expresser group (only CYP3A5*3 alleles). The primary outcome was time to achieve a steady therapeutic TAC concentration. Secondary outcomes include incidence of early allograft rejection and calcineurin inhibitor (CNI) nephrotoxicity during the first year post-transplant. RESULTS: The study cohort included 55 (56%) expressers and 43 (44%) non-expressers of the CYP3A5*1 allele. Expressers had a significantly longer time to achieve a steady therapeutic TAC concentration than non-expressers (log rank, P = 0.03). Expressers had a trend for higher incidence of early allograft rejection (29.1% vs 16.3%, log rank, P = 0.16). Early biopsy-proven CNI nephrotoxicity was seen in 60% of recipients, with no differences in the rate between expressers and non-expressers. CONCLUSIONS: Pediatric kidney transplant recipients with the CYP3A5*1 allele (expressers) take a longer time to achieve therapeutic TAC levels than those with the CYP3A5*3 allele (non-expressers). However, we observed no significant differences in acute rejection or CNI nephrotoxicity based on CYP3A5 genotype. Thus CYP3A5 genotype was not observed to have an immediate impact on early transplant outcomes.

Cytomegalovirus and Epstein-Barr virus infections among pediatric kidney transplant recipients at a center using universal Valganciclovir Prophylaxis.

BACKGROUND: CMV is associated with adverse effects in renal transplant recipients. The objective of this study was to characterize the incidence and timing of CMV and EBV infections in relation to valGCV prophylaxis in a pediatric renal transplant cohort. METHODS: Retrospective cohort of pediatric renal transplant patients given universal valGCV prophylaxis and universal viral surveillance was evaluated. Demographics, prophylaxis, acute rejection, and CMV and EBV infections were abstracted. RESULTS: A total of 92 pediatric renal allograft recipients, 2008-2013, were included. One or more viral infections developed in 77/92 (83.7%) of the patients. EBV was the most common in 62/92 (67%) patients, irrespective of valGCV (82% of episodes occurring on valGCV). CMV DNAemia occurred in 30/92 (33%) patients, 14 episodes (47%) occurring on valGCV. Incidence of breakthrough CMV on prophylaxis was 15% and was associated with persistent DNAemia (OR 7.8, CI:1.6-32.9, P < 0.02). CMV tissue-invasive disease was not seen. CMV syndrome occurred in 10% of the cohort, only in CMV D+ patients, and only one symptomatic breakthrough infection required treatment. Out of 92, 21 (23%) had simultaneous co-infections with 2-3 viruses. CONCLUSIONS: Viral infections in pediatric renal transplant recipients receiving universal valGCV prophylaxis were common. EBV infections were not reduced by valGCV prophylaxis, and nearly half of CMV infections occurred on valGCV. Symptomatic CMV infection while on prophylaxis was rare. valGCV prophylaxis may prevent symptomatic CMV infection but not EBV infection, and frequent CMV surveillance in pediatric renal transplant recipients on prophylaxis may not be necessary.

Hyperfiltration during early childhood precedes albuminuria in pediatric sickle cell nephropathy.

BACKGROUND: In patients with diabetes mellitus, hyperfiltration precedes the development of albuminuria. Pediatric sickle cell anemia (SCA) patients have a high prevalence of hyperfiltration and albuminuria during early childhood and adolescence. We tested the hypothesis that hyperfiltration precedes the development of albuminuria in a longitudinal pediatric SCA cohort. METHODS: We identified 91 participants with HbSS or SB0 thalassemia 5-21 years of age enrolled in a longitudinal sickle cell nephropathy cohort study who had a cystatin C measured during early childhood (4-10 years of age). Early hyperfiltration was defined as a mean eGFR >180 mL/min/1.73m2 using cystatin C obtained from 4 to 10 years of age. Persistent albuminuria was defined as an albumin to creatinine ratio > 30 mg/g on two of three untimed urine specimens. Time to event analysis estimated survival curves for participants with and without hyperfiltration using Kaplan-Meier curves and used logrank test for categorical variables to assess the association with time to development of the first episode persistent albuminuria. RESULTS: Persistent albuminuria occurred more often and at an earlier age in participants with early hyperfiltration compared to those without early hyperfiltration (log-rank, P = .004). Participants who developed albuminuria have a significant increase in their eGFR during childhood (P = .003) as compared to participants who have not yet progressed to albuminuria (P = .26). For every 1 g/dL increase in hemoglobin, the hazard ratio for developing persistent proteinuria decreased by 0.56 (95% CI: 0.3, 1.06, P = .07). CONCLUSION: Hyperfiltration precedes the development of persistent proteinuria in pediatric SCA patients. Intervention strategies should target lowering eGFR during early childhood.

Phase I study of single-dose pharmacokinetics and pharmacodynamics of belatacept in adolescent kidney transplant recipients.

Belatacept is an intravenously infused selective T cell costimulation blocker approved for preventing organ rejection in renal transplant recipients aged ≥18 years. This phase I trial examined the pharmacokinetics and pharmacodynamics (percentage CD86 receptor occupancy [%CD86RO]) of a single dose of belatacept (7.5 mg/kg) administered to kidney transplant recipients aged 12-17 years receiving a stable calcineurin inhibitor-based immunosuppressive regimen. Nine adolescents (mean age 15.1 years) who were seropositive for Epstein-Barr virus were enrolled; all completed the 6-month study. Pharmacokinetics suggested relatively low variability of exposure (coefficients of variation for maximum observed serum concentration [Cmax ] and area under the serum concentration-time curve from time zero extrapolated to infinity [AUC0-INF ] were 20% and 25%, respectively). Mean half-life (T1/2 ) occurred 7.2 days postinfusion. Belatacept total body clearance was 0.48 mL/h/kg, and volume of distribution at steady-state (Vss ) was low at 0.09 L/kg. Compared with historical data from healthy adult volunteers administered a single dose of belatacept 10 mg/kg and adult kidney transplant recipients administered multiple doses of belatacept 5 mg/kg, pharmacokinetic values for adolescents were similar, indicating consistency across adolescent and adult populations. Mean %CD86RO increased with increasing belatacept concentration, indicating a direct relationship between pharmacokinetics and pharmacodynamics. Four patients reported 7 serious adverse events; none was considered related to belatacept. These data will inform belatacept dose selection in future studies of adolescent kidney transplant recipients.

Rituximab treatment for chronic steroid-dependent Henoch-Schonlein purpura: 8 cases and a review of the literature.

BACKGROUND: Henoch-Schonlein purpura (HSP) is a small vessel vasculitis that is characterized by non-thrombocytopenic purpura, abdominal pain, arthritis, and glomerulonephritis. Typically, HSP is self-limited requiring only supportive care, but more severe cases may require corticosteroid (CS) treatment. Rarely, a subset of these patients has persistent rash, arthritis, abdominal involvement, or renal disease despite treatment with CS, or has disease recurrence on CS tapering. Refractory HSP has been effectively treated with a variety of CS sparing therapies. For life-threatening refractory HSP, the B cell depleting agent, rituximab (RTX), has been reported as beneficial for children with substantial renal or central nervous system involvement. However, RTX use for children with less severe HSP, but chronic CS dependent disease refractory to CS sparing immunomodulatory agents, has been less well explored. Herein, we describe 8 children treated with RTX for chronic refractory HSP and report a reduction in recurrent hospitalizations and eventual CS discontinuation. METHODS: This is a retrospective analysis of eight children who were treated with RTX for chronic CS dependent HSP during the years 2006-2014 at a single institution. A chart review of the electronic medical record was performed to determine the presenting symptoms, the type and duration of treatment received, and the number of hospitalizations prior to and after RTX. The number of hospitalizations and oral corticosteroid burden were analyzed using the Wilcoxon signed rank test. RESULTS: Prior to receiving RTX, seven patients had at least one hospitalization for HSP (median 1.5, range 0-3). Following RTX, only two patients were hospitalized, each a single time for recurrent abdominal pain. The median oral CS burden was 0.345 mg/kg/day before RTX and 0 mg/kg/day at 6 months (p = 0.078), 1 year (p = 0.0625), and 2 years (p = 0.03) following RTX infusion. Seven out of eight children met remission criteria, defined as no active rash, arthritis, nephritis (hematuria and proteinuria), or gastrointestinal distress following RTX. No serious adverse events were noted. CONCLUSION: Overall, RTX effectively reduced the number of hospital admissions and oral CS burden. RTX also helped most all children achieve clinical remission. RTX appears to be an effective and safe alternative for chronic CS dependent and immunomodulatory refractory childhood HSP.

Subclinical inflammation phenotypes and long-term outcomes after pediatric kidney transplantation.

The implementation of surveillance biopsies in pediatric kidney transplantation remains controversial. Surveillance biopsies detect subclinical injury prior to clinical dysfunction, which could allow for early interventions that prolong allograft survival. We conducted a single-center retrospective cohort study of 120 consecutive pediatric kidney recipients, of whom 103 had surveillance biopsies ≤6 months posttransplant. We tested the hypothesis that subclinical inflammation (borderline or T cell-mediated rejection without clinical dysfunction) is associated with a 5-year composite endpoint of acute rejection and allograft failure. Overall, 36% of subjects had subclinical inflammation, which was associated with increased hazard for the composite endpoint (adjusted hazard ratio 2.89 [1.27, 6.57]; P < .01). Subjects with treated vs untreated subclinical borderline rejection had a lower incidence of the composite endpoint (41% vs 67%; P < .001). Subclinical vascular injury (subclinical inflammation with Banff arteritis score > 0) had a 78% incidence of the composite endpoint vs 11% in subjects with no major surveillance abnormalities (P < .001). In summary, we showed that subclinical inflammation phenotypes were prevalent in pediatric kidney recipients without clinical dysfunction and were associated with increased acute rejection and allograft failure. Once prospectively validated, our data would support implementation of surveillance biopsies as standard of care in pediatric kidney transplantation.

Effect of Febuxostat on Ambulatory Blood Pressure in Subjects With Hyperuricemia and Hypertension: A Phase 2 Randomized Placebo-Controlled Study.

BACKGROUND: Hyperuricemia is associated with hypertension, with elevated serum uric acid levels postulated to have a causal role in the development of hypertension. Consequently, serum uric acid reduction may help lower blood pressure (BP). A Phase 2, double-blind, placebo-controlled trial was conducted to assess the potential BP-lowering effects of the xanthine oxidase inhibitor febuxostat in subjects with hypertension and hyperuricemia (serum uric acid ≥0.42 mmol/L [≥7.0 mg/dL]). METHODS AND RESULTS: Subjects (n=121) were randomized 1:1 to febuxostat 80 mg once daily or to placebo. The primary end point was change from baseline to Week 6 in 24-hour mean ambulatory systolic BP (SBP). Additional end points included the following: change from baseline to Week 3 in 24-hour mean SBP and changes from baseline to Weeks 3 and 6 in 24-hour mean ambulatory diastolic BP, serum uric acid, mean daytime and nighttime ambulatory SBP/diastolic BP, and clinic SBP/diastolic BP. For the overall study population, there were no significant differences between febuxostat and placebo for changes from baseline to Weeks 3 or 6 in ambulatory, daytime or nighttime, or clinic SBP or diastolic BP. However, in a preplanned subgroup analysis, there was a significant decrease in SBP from baseline to Week 6 in subjects with normal renal function (estimated glomerular filtration rate ≥90 mL/min) treated with febuxostat versus placebo; least squares mean difference, -6.7; 95% confidence interval -13.3 to -0.0; P=0.049. CONCLUSIONS: This study suggests that febuxostat may lower BP in hyperuricemic patients with hypertension and normal renal function; further studies should be conducted to confirm this finding. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01496469.

Evaluating risk factors for chronic kidney disease in pediatric patients with sickle cell anemia.

BACKGROUND: Patients with sickle cell anemia (SCA) have an increased prevalence of nephropathy and mortality from chronic kidney disease (CKD). METHODS: We evaluated the association of hyperuricemia and nocturnal hypertension with lower estimated glomerular filtration rate (eGFR) using cystatin-C in patients aged 10-21 years with the HbSS or HbSB0 form of the disease during a non-acute clinic visit. eGFR and uric acid measurements were obtained in 83 and 81 participants, respectively, and 24-h ambulatory blood pressure monitoring (ABPM) was performed in 44 participants. Annual testing included vital signs, complete blood count, comprehensive metabolic panel, medications, urine microalbumin/creatinine, and lactate dehydrogenase measurements. Hyperuricemia was defined as a uric acid level of ≥5.5 mg/dL. Nocturnal hypertension was defined as >25% of nocturnal readings at >95th percentile according to norms established by the American Heart Association Statement on ABPM in children and adolescents. RESULTS: The mean eGFR was statistically significantly lower in patients with hyperuricemia than in those with normal uric acid levels (143 vs. 161 mL/min/1.73 m2, respectively). Of the 44 participants for whom ABPM data were available, 14 (32%) had systolic nocturnal hypertension and 12 (27%) had diastolic nocturnal hypertension. The mean eGFR was statistically significantly lower in participants with nocturnal systolic and diastolic hypertension than in those with normal nocturnal blood pressure. In a regression model, nocturnal hypertension and hyperuricemia were associated with a lower eGFR. CONCLUSIONS: Two risk factors for CKD, i.e., nocturnal hypertension and hyperuricemia, were associated with lower eGFR in older children and adolescent patients with SCA. Long-term studies on their association with progression to CKD in this population are warranted. KEY POINT: Nocturnal hypertension and hyperuricemia are established risk factors for nephropathy in other diseases and may play a role in SCA nephropathy.