Comparative Effect of Contrast Media Type on the Incidence of Contrast-Induced Nephropathy: A Systematic Review and Meta-analysis.

BACKGROUND: Iodine contrast media are essential components of many imaging procedures. An important potential side effect is contrast-induced nephropathy (CIN). PURPOSE: To compare CIN risk for contrast media within and between osmolality classes in patients receiving diagnostic or therapeutic imaging procedures. DATA SOURCES: PubMed, EMBASE, Cochrane Library, Clinical Trials.gov, and Scopus through June 2015. STUDY SELECTION: Randomized, controlled trials that reported CIN-related outcomes in patients receiving low-osmolar contrast media (LOCM) or iso-osmolar contrast media for imaging. DATA EXTRACTION: Independent study selection and quality assessment by 2 reviewers and dual extraction of study characteristics and results. DATA SYNTHESIS: None of the 5 studies that compared types of LOCM reported a statistically significant or clinically important difference among study groups, but the strength of evidence was low. Twenty-five randomized, controlled trials found a slight reduction in CIN risk with the iso-osmolar contrast media agent iodixanol compared with a diverse group of LOCM that just reached statistical significance in a meta-analysis (pooled relative risk, 0.80 [95% CI, 0.65 to 0.99]; P = 0.045). This comparison's strength of evidence was moderate. In a meta regression of randomized, controlled trials of iodixanol, no relationship was found between route of administration and comparative CIN risk. LIMITATIONS: Few studies compared LOCM. Procedural details about contrast administration were not uniformly reported. Few studies specified clinical indications or severity of baseline renal impairment. CONCLUSION: No differences were found in CIN risk among types of LOCM. Iodixanol had a slightly lower risk for CIN than LOCM, but the lower risk did not exceed a criterion for clinical importance. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality.

Effectiveness of Prevention Strategies for Contrast-Induced Nephropathy: A Systematic Review and Meta-analysis.

BACKGROUND: N-acetylcysteine, sodium bicarbonate, statins, and ascorbic acid have been studied for reducing contrast-induced nephropathy (CIN). PURPOSE: To evaluate the comparative effectiveness of interventions to reduce CIN in adults receiving contrast media. DATA SOURCES: MEDLINE, EMBASE, Cochrane Library, ClinicalTrials.gov, and Scopus databases through June 2015. Risk of bias and overall strength of evidence (SOE) of studies were assessed. STUDY SELECTION: Randomized, controlled trials of N-acetylcysteine, sodium bicarbonate, statins, or ascorbic acid that used intravenous (IV) or intra-arterial contrast media and defined CIN with enough data for meta-analysis. DATA EXTRACTION: Two reviewers independently extracted data and assessed study quality. DATA SYNTHESIS: Low-dose N-acetylcysteine plus IV saline compared with IV saline (risk ratio [RR], 0.75 [95% CI, 0.63 to 0.89]; low SOE), N-acetylcysteine plus IV saline compared with IV saline in patients receiving low-osmolar contrast media (RR, 0.69 [CI, 0.58 to 0.84]; moderate SOE), and statins plus N-acetylcysteine plus IV saline versus N-acetylcysteine plus IV saline (RR, 0.52 [CI, 0.29 to 0.93]; low SOE) had clinically important and statistically significant benefits. The following 3 comparisons suggested a clinically important difference that was not statistically significant: sodium bicarbonate versus IV saline in patients receiving low-osmolar contrast media (RR, 0.65 [CI, 0.33 to 1.25]; low SOE), statins plus IV saline versus IV saline (RR, 0.68 [CI, 0.39 to 1.20]; low SOE), and ascorbic acid versus IV saline (RR, 0.72 [CI, 0.48 to 1.01]; low SOE). Strength of evidence was generally insufficient for comparisons of the need for renal replacement, cardiac events, and mortality. LIMITATION: Too few studies were done in patients receiving IV contrast media. CONCLUSION: The greatest reduction in CIN was seen with N-acetylcysteine plus IV saline in patients receiving LOCM and with statins plus N-acetylcysteine plus IV saline. PRIMARY FUNDING SOURCE: Agency for Healthcare Research and Quality.

Blood dendritic cell levels associated with impaired IL-12 production and T-cell deficiency in patients with kidney disease: implications for post-transplant viral infections.

Reduced pretransplant blood myeloid dendritic cell (mDC) levels are associated with post-transplant BK viremia and cytomegalovirus (CMV) disease after kidney transplantation. To elucidate potential mechanisms by which mDC levels might influence these outcomes, we studied the association of mDC levels with mDC IL-12 production and T-cell level/function. Peripheral blood (PB) was studied in three groups: (i) end stage renal disease patients on hemodialysis (HD; n = 81); (ii) chronic kidney disease stage IV-V patients presenting for kidney transplant evaluation or the day of transplantation (Eval/Tx; n = 323); and (iii) healthy controls (HC; n = 22). Along with a statistically significant reduction in mDC levels, reduced CD8(+) T-cell levels were also demonstrated in the kidney disease groups compared with HC. Reduced PB mDC and monocyte-derived DC (MoDC) IL-12 production was observed after in vitro LPS stimulation in the HD versus HC groups. Finally, ELISpot assays demonstrated less robust CD3(+) INF-γ responses by MoDCs pulsed with CMV pp65 peptide from HD patients compared with HC. PB mDC level deficiency in patients with kidney disease is associated with deficient IL-12 production and T-cell level/function, which may explain the known correlation of CD8(+) T-cell lymphopenia with deficient post-transplant antiviral responses.

Effects of sodium intake and diet on racial differences in urinary potassium excretion: results from the Dietary Approaches to Stop Hypertension (DASH)-Sodium trial.

BACKGROUND: We previously showed that African Americans excreted less urinary potassium than whites, even while consuming similar diets in the Dietary Approaches to Stop Hypertension (DASH) trial. We hypothesized that a low-sodium diet may eliminate these differences. STUDY DESIGN: Data from the DASH-Sodium randomized controlled feeding trial were analyzed. SETTING & PARTICIPANTS: 412 adults with prehypertension or stage 1 hypertension. INTERVENTION: Random assignment to either a typical American "control" diet (1.7 g [43 mEq] potassium/2,100 kcal/d) or the DASH diet (4.1 g [105 mEq] potassium/2,100 kcal/d). Within each diet, participants received 3 levels of sodium intake in random order for 30 days. OUTCOMES & MEASUREMENTS: 24-hour urine samples were analyzed at the end of each period. The primary outcome was urinary potassium excretion. RESULTS: On the DASH diet, African Americans consistently excreted significantly less urinary potassium (mean 24-hour urinary potassium excretion, 2,594 ± 961 mg [66 ± 25 mEq]) than whites (3,412 ± 1,016 mg [87 ± 26 mEq]) at the highest sodium level; adjusted (P < 0.001); this difference was not altered by sodium level (P = 0.6 comparing white to African American difference in urinary potassium excretion on high- vs low-sodium diet). In contrast, there was a smaller but significant white-African American difference in mean daily urinary potassium excretion in participants fed the control/high-sodium diet that was not present in the control/low-sodium diet (adjusted differences of 281 mg [7 mEq]/d vs 20 mg [0.5 mEq]/d, respectively; P = 0.007). Significant interactions were found between race and diet (P < 0.001) and between race and sodium (P = 0.02). LIMITATIONS: Single rather than multiple urine collections were available at each time. Lack of stool potassium and sweat potassium values. CONCLUSIONS: Racial differences in urinary potassium excretion depend on sodium intake and diet. Our results may help explain the previously documented large variability in urinary potassium excretion.

Urinary sodium is a potent correlate of proteinuria: lessons from the chronic renal insufficiency cohort study.

BACKGROUND: While higher blood pressure is known to increase proteinuria, whether increased dietary sodium as estimated from 24-hour urinary excretion correlates with increased proteinuria in patients with chronic kidney disease (CKD) is not well studied. METHODS: We measured 24-hour urinary sodium, potassium and protein excretion in 3,680 participants in the Chronic Renal Insufficiency Cohort study, to determine the relationship between urinary sodium and potassium and urinary protein excretion in patients with CKD. We stratified our data based on the presence or absence of diabetes given the absence of any data on this relationship and evidence that diabetics had greater urinary protein excretion at nearly every level of urinary sodium excretion. Multiple linear regressions were used with a stepwise inclusion of covariates such as systolic blood pressure, demographics, hemoglobin A1c and type of antihypertensive medications to evaluate the relationship between urinary electrolyte excretion and proteinuria. RESULTS: Our data demonstrated that urinary sodium (+1 SD above the mean), as a univariate variable, explained 12% of the variation in proteinuria (ß = 0.29, p < 0.0001), with rising urinary sodium excretion associated with increasing proteinuria. The significance of that relationship was only partially attenuated with adjustment for demographic and clinical factors and the addition of 24-hour urinary potassium to the model (ß = 0.13, R(2) = 0.35, p < 0.0001). CONCLUSIONS: An understanding of the relationship between these clinical factors and dietary sodium may allow a more tailored approach for dietary salt restriction in patients with CKD.

Association of hypo- and hyperkalemia with disease progression and mortality in males with chronic kidney disease: the role of race.

BACKGROUND/AIMS: Abnormal serum potassium is associated with higher mortality in dialysis patients, but its impact on outcomes in predialysis chronic kidney disease (CKD) is less clear. Furthermore, blacks with normal kidney function have lower urinary potassium excretion, but it is unclear if such differences have a bearing on race-associated outcomes in CKD. METHODS: We studied predialysis mortality and slopes of estimated glomerular filtration rate, eGFR) associated with serum potassium in 1,227 males with CKD. Mortality was examined in time-dependent Cox models, and slopes of eGFR in linear mixed effects models with adjustments for case mix and laboratory values. RESULTS: Both hypo- and hyperkalemia were associated with mortality overall and in 933 white patients, but in 294 blacks hypokalemia was a stronger death predictor. Hypokalemia was associated with loss of kidney function independent of race: a 1 mEq/l lower potassium was associated with an adjusted difference in slopes of eGFR of -0.13 ml/min/1.73 m(2)/year (95% CI: -0.20 to -0.07), p < 0.001. CONCLUSION: Hypo- and hyperkalemia are associated with higher mortality in CKD patients. Blacks appear to better tolerate higher potassium than whites. Hypokalemia is associated with faster CKD progression independent of race. Hyperkalemia management may warrant race-specific consideration, and hypokalemia correction may slow CKD progression.

Randomized Trial on the Effects of Dietary Potassium on Blood Pressure and Serum Potassium Levels in Adults with Chronic Kidney Disease.

In the general population, an increased potassium (K) intake lowers blood pressure (BP). The effects of K have not been well-studied in individuals with chronic kidney disease (CKD). This randomized feeding trial with a 2-period crossover design compared the effects of diets containing 100 and 40 mmol K/day on BP in 29 adults with stage 3 CKD and treated or untreated systolic BP (SBP) 120-159 mmHg and diastolic BP (DBP) <100 mmHg. The primary outcome was 24 h ambulatory systolic BP. The higher-versus lower-K diet had no significant effect on 24 h SBP (-2.12 mm Hg; p = 0.16) and DBP (-0.70 mm Hg; p = 0.44). Corresponding differences in clinic BP were -4.21 mm Hg for SBP (p = 0.054) and -0.08 mm Hg for DBP (p = 0.94). On the higher-K diet, mean serum K increased by 0.21 mmol/L (p = 0.003) compared to the lower-K diet; two participants had confirmed hyperkalemia (serum K ≥ 5.5 mmol/L). In conclusion, a higher dietary intake of K did not lower 24 h SBP, while clinic SBP reduction was of borderline statistical significance. Additional trials are warranted to understand the health effects of increased K intake in individuals with CKD.

Racial differences in urinary potassium excretion.

Racial differences in potassium (K) intake and urinary K excretion may contribute to the higher BP observed in black compared with white individuals. Although black individuals typically consume less dietary K than white individuals, the lower urinary K excretion observed in black individuals may reflect more than differences in intake. In this study, data from the Dietary Approaches to Stop Hypertension (DASH) trial (413 white and black participants) were used to evaluate urinary K excretion in black and white individuals with similar K intake. At screening, mean urinary K excretion was higher in white than black individuals (mean Delta = 645 mg/d for white minus black individuals, adjusted for age, gender, and weight; P < 0.001). After a 3-wk run-in period during which all participants received a low-K control diet, a significant racial difference remained (mean Delta = 201 mg/d, adjusted for age, gender, and caloric intake; P < 0.001). Participants were then randomly assigned to continue the control diet or switch to a high-K diet (either a high fruit/vegetable diet or the DASH diet) for 8 wk. At the end of intervention, the mean difference in urinary K in white compared with black individuals after adjustment for age, gender, and caloric intake was -6 mg/d (P = 0.95) in the control group, 163 mg/d in the fruits/vegetables group (P = 0.39), and 903 mg/d in the DASH group (P < 0.001). Racial differences in urinary K excretion seem to reflect more than intake differences; further studies are needed to understand their potential impact on clinical outcomes.

Hepatorenal syndrome.

Hepatorenal syndrome (HRS) is a "functional" and reversible form of renal failure that occurs in patients with advanced chronic liver disease. The distinctive hallmark feature of HRS is the intense renal vasoconstriction caused by interactions between systemic and portal hemodynamics. This results in activation of vasoconstrictors and suppression of vasodilators in the renal circulation. Epidemiology, pathophysiology, as well as current and emerging therapies of HRS are discussed in this review.

The effects of n-3 long-chain polyunsaturated fatty acid supplementation on biomarkers of kidney injury in adults with diabetes: results of the GO-FISH trial.

OBJECTIVE Long-chain n-3 polyunsaturated fatty acid (n-3 PUFA) supplements may have renoprotective effects in patients with diabetes, but previous trials have been inconsistent. We performed a randomized controlled trial of n-3 PUFA supplementation on urine albumin excretion and markers of kidney injury in adults with type 2 diabetes. RESEARCH DESIGN AND METHODS We conducted a randomized, placebo-controlled, two-period crossover trial to test the effects of 4 g/day of n-3 PUFA supplementation on markers of glomerular filtration and kidney injury in adults with adult-onset diabetes and greater than or equal to trace amounts of proteinuria. Each period lasted 6 weeks and was separated by a 2-week washout. The main outcome was urine albumin excretion and, secondarily, markers of kidney injury (kidney injury molecule-1, N-acetyl ß-d-glucosaminidase [NAG], neutrophil gelatinase-associated lipocalin [NGAL], and liver fatty acid-binding protein [LFABP]), serum markers of kidney function (cystatin C, ß2-microglobulin, and creatinine), and estimated glomerular filtration rate (eGFR). RESULTS Of the 31 participants, 29 finished both periods. A total of 55% were male, and 61% were African American; mean age was 67 years. At baseline, mean BMI was 31.6 kg/m(2), median eGFR was 76.9 mL/min/1.73 m(2), and median 24-h urine albumin excretion was 161 mg/day. Compared with placebo, n-3 PUFA had nonsignificant effects on urine albumin excretion (-7.2%; 95% CI -20.6 to 8.5; P = 0.35) and significant effects on urine NGAL excretion (-16% [-29.1 to -0.5%]; P = 0.04). There was no effect on serum markers of kidney function or eGFR. In subgroup analyses, there were significant decreases in 24-h urinary excretion of albumin, NGAL, LFABP, and NAG among participants taking medications that block the renin-angiotensin-aldosterone system (RAAS). CONCLUSIONS These results suggest a potential effect of n-3 PUFA supplementation on markers of kidney injury in patients with diabetes and early evidence of kidney disease. In the context of prior studies, these results provide a strong rationale for long-term trials of n-3 PUFA on chronic kidney disease progression.

A comparison of web sites used to manage and present home blood pressure readings.

Home blood pressure (HBP) monitoring is now recommended as a routine component of blood pressure management in patients with known or suspected hypertension. Over the last few years, a large number of Web sites, commonly termed Personal Health Records, have been developed so that patients can manage and present HBP readings. The objective of this report is to describe and compare these Web sites. A list of 33 desirable Web site features, organized into 4 categories, was developed. Between June and August of 2009, a total of 60 Web sites was identified, of which 20 were free or free to try. Each of the 20 Web sites displayed HBP readings in tabular and graphical formats, most offered an option to print results in tabular (70%) and graphical (70%) form, and many (47%) could download HBP data from Microsoft HealthVault. In contrast, none of the Web sites directly linked with common electronic medical records. Overall, Web sites offered between 41% and 77% of the 33 features considered desirable. In conclusion, there is considerable variation in available features on Web sites used to manage HBP data. Information presented in this report should be useful to physicians and patients in selecting a Web site for managing and presenting HBP readings and ultimately improving blood pressure control.

Regulation of NHE3, NKCC2, and NCC abundance in kidney during aldosterone escape phenomenon: role of NO.

Escape from aldosterone-induced renal NaCl retention is an important homeostatic mechanism in pathophysiological states in which plasma aldosterone levels are inappropriately elevated, e.g., in primary aldosteronism. Our previous studies demonstrated that the escape process occurs largely as a result of a marked suppression of the abundance of the thiazide-sensitive Na-Cl cotransporter (NCC) of the distal convoluted tubule but have also demonstrated a paradoxical increase in the protein abundance of the apical Na/H exchanger of the proximal tubule (NHE3). In the present study, we confirmed the increase in NHE3 and also showed that a similar increase in NHE3 protein abundance occurs in escape from ANG II-mediated NaCl retention. To investigate the potential role of nitric oxide (NO) in the observed upregulation of NHE3, we repeated the aldosterone escape experiment with a superimposed infusion of a NO synthase inhibitor, NG-nitro-l-arginine methyl ester (l-NAME). l-NAME infusion abolished the increase in NHE3 protein abundance. Furthermore, in a different experiment, NO synthase inhibition uncovered an associated decrease in the abundance of the Na-K-2Cl cotransporter (NKCC2) of the thick ascending limb, not seen with simple aldosterone escape. However, NO synthase inhibition did not block the decrease in NCC abundance normally seen with aldosterone escape. Furthermore, l-NAME infusion in aldosterone-treated rats markedly decreased both NHE3 and NKCC2 protein abundance, without changes in the corresponding mRNA levels. We conclude that NHE3 and NKCC2 protein abundances in kidney are positively regulated by NO and that the increase in NHE3 abundance seen in the aldosterone escape phenomenon is NO dependent.

Long-term regulation of ENaC expression in kidney by angiotensin II.

We carried out semiquantitative immunoblotting of kidney to identify apical sodium transporter proteins whose abundances are regulated by angiotensin II. In NaCl-restricted rats (0.5 mEq Na/200 g BW/d), the type 1 angiotensin II receptor (AT1 receptor) antagonist, candesartan, (1 mg/kg of body weight per day SC for 2 days) markedly decreased the abundance of the alpha subunit of the epithelial sodium channel (ENaC). This subunit has been shown to be rate-limiting for assembly of mature ENaC complexes. In addition, systemic infusion of angiotensin II increased alphaENaC protein abundance in rat kidney cortex. The decrease in alphaENaC protein abundance in response to AT1 receptor blockade was associated with a fall in alphaENaC mRNA abundance (real-time RT-PCR), consistent with transcriptionally mediated regulation. The effect of AT1 receptor blockade on alphaENaC expression was not blocked by spironolactone, suggesting a direct role of the AT1 receptor in regulation of alphaENaC gene expression. Candesartan administration was also found to increase the abundances of the beta and gamma subunits. The increase in beta and gammaENaC protein abundance was not associated with a significant increase in the renal abundances of the corresponding mRNAs, suggesting a posttranscriptional mechanism. Immunocytochemistry confirmed the increase in beta and gammaENaC protein abundance and demonstrated candesartan-induced ENaC internalization in collecting duct cells. The results support the view that the angiotensin II receptor regulates ENaC abundance, consistent with a role for angiotensin II in regulation of collecting duct function.