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Renal Imaging: Core Curriculum 2019.
Fried, JG, Morgan, MA
American journal of kidney diseases : the official journal of the National Kidney Foundation. 2019;(4):552-565
Abstract
Renal imaging has become a fundamental part of clinical care for patients with kidney disease. Imaging strategies for the kidney have been evolving during the past hundred years and have been even more rapidly changing during the past couple of decades due to the development of modern computed tomographic techniques, magnetic resonance imaging, and more sophisticated ultrasonographic techniques, such as contrast-enhanced ultrasonography. Applying the correct radiologic study for the clinical situation maximizes the diagnostic accuracy of the imaging, and a judicious choice between techniques helps limit radiation dose and potential adverse events. This Core Curriculum outlines the imaging modalities currently in use in radiology departments and is divided into 3 sections: (1) a review of the development of renal imaging and an outline of modalities available to the nephrologist, (2) imaging strategies for select clinical situations, and (3) a discussion of some potential adverse events from imaging, including effects of iodinated contrast on kidney function, risks of gadolinium-based contrast agents in kidney failure, and potential risks of imaging techniques that use ionizing radiation.
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2.
The renal molecular clock: broken by aging and restored by exercise.
Schmitt, EE, Johnson, EC, Yusifova, M, Bruns, DR
American journal of physiology. Renal physiology. 2019;(5):F1087-F1093
Abstract
The mammalian circadian clock governs physiological, endocrine, and metabolic responses coordinated in a 24-h rhythmic pattern by the suprachiasmatic nucleus (SCN) of the anterior hypothalamus. The SCN also dictates circadian rhythms in peripheral tissues like the kidney. The kidney has several important physiological functions, including removing waste and filtering the blood and regulating fluid volume, blood osmolarity, blood pressure, and Ca2+ metabolism, all of which are under tight control of the molecular/circadian clock. Normal aging has a profound influence on renal function, central and peripheral circadian rhythms, and the sleep-wake cycle. Disrupted circadian rhythms in the kidney as a result of increased age likely contribute to adverse health outcomes such as nocturia, hypertension, and increased risk for stroke, cardiovascular disease, and end organ failure. Regular physical activity improves circadian misalignment in both young and old mammals, although the precise mechanisms for this protection remain poorly described. Recent advances in the heart and skeletal muscle literature suggest that regular endurance exercise entrains peripheral clocks, and we propose that similar beneficial adaptations occur in the kidney through regulation of renal blood flow and fluid balance.
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Switching Lamivudine with Adefovir Dipivoxil Combination Therapy to Entecavir Monotherapy Provides Better Viral Suppression and Kidney Safety.
Lian, JS, Zhang, XL, Lu, YF, Chen, JY, Zhang, YM, Jia, HY, Zhang, Z, Yang, YD
International journal of medical sciences. 2019;(1):17-22
Abstract
Introduction: Most chronic hepatitis B (CHB) patients in China are primitively treated with a combination of lamivudine (LAM) and adefovir dipivoxil (ADV). Although antiviral resistance can be avoided with this combination therapy, using it can have harmful side effects related to ADV, specifically kidney and bone injury. This study was designed to compare viral suppression and kidney safety when switching LAM and ADV combination therapy de novo to entecavir (ETV) monotherapy in patients with CHB and compensated hepatic cirrhosis. Materials and methods: In total, 360 CHB and compensated liver cirrhosis patients who received treatment of LAM and ADV combination therapy for more than 1 year were included in this study. One hundred and eighty patients continued combination therapy to serve as a control group and the other 180 patients were switched to ETV monotherapy to serve as the experimental group. The total course of therapy was 3 years. Laboratory studies were done every 3 months to measure liver and kidney function. Studies included glomerular filtration rate (eGFR), HBV-DNA, urine β2-microglobulin (β2-M) and retinol binding protein (RBP). Results: In the experimental group, an HBV-DNA level below 20 IU/ml was found in 77.65%, 85.88%, and 94.77% in years 1, 2, and 3, respectively. In the control group, HBV-DNA levels were below 20 IU/ml in 69.66%, 75.42%, and 85.80% in years 1, 2, and 3, respectively. Low HBV-DNA levels in the experimental group were significantly less common than in the control group on the second and third year; P values were 0.009 and 0.006 for years 2 and 3, respectively. The cumulative genetic mutation rate was 3.49% in the experimental group and 8.88% in the control group (P=0.044). Decreases in eGFR more than 30% from baseline were found in 0%, 0.56%, and 1.74% of patients in the experimental group and 4.49%, 9.14% and 14.79% in patients in the control group in the first, second, and third year, respectively. Serum creatinine more than 50 μmol/L above baseline was found in 0%, 0% and 1.74% of patients in the experimental group and 1.12%, 4.00% and 5.32% of patients in the control group in years 1, 2, and 3, respectively. The urine β2-M and RBP levels were abnormal more often in the experimental group than in the control group. Conclusion: Switching to ETV monotherapy can decrease HBV-DNA levels, reduce the genetic mutation rate, and prevent renal damage caused by LAM and ADV combination therapy in patients with CHB and compensated liver cirrhosis. Patients receiving LAM and ADV combination therapy de novo should be switched to ETV monotherapy immediately.
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Cardiorenal sodium MRI at 7.0 Tesla using a 4/4 channel 1 H/23 Na radiofrequency antenna array.
Boehmert, L, Kuehne, A, Waiczies, H, Wenz, D, Eigentler, TW, Funk, S, von Knobelsdorff-Brenkenhoff, F, Schulz-Menger, J, Nagel, AM, Seeliger, E, et al
Magnetic resonance in medicine. 2019;(6):2343-2356
Abstract
PURPOSE Cardiorenal syndrome describes disorders of the heart and the kidneys in which a dysfunction of 1 organ induces a dysfunction in the other. This work describes the design, evaluation, and application of a 4/4-channel hydrogen-1/sodium (1 H/23 Na) RF array tailored for cardiorenal MRI at 7.0 Tesla (T) for a better physiometabolic understanding of cardiorenal syndrome. METHODS The dual-frequency RF array is composed of a planar posterior section and a modestly curved anterior section, each section consisting of 2 loop elements tailored for 23 Na MR and 2 loopole-type elements customized for 1 H MR. Numerical electromagnetic field and specific absorption rate simulations were carried out. Transmission field ( B1+ ) uniformity was optimized and benchmarked against electromagnetic field simulations. An in vivo feasibility study was performed. RESULTS The proposed array exhibits sufficient RF characteristics, B1+ homogeneity, and penetration depth to perform 23 Na MRI of the heart and kidney at 7.0 T. The mean B1+ field for sodium in the heart is 7.7 ± 0.8 µT/√kW and in the kidney is 6.9 ± 2.3 µT/√kW. The suitability of the RF array for 23 Na MRI was demonstrated in healthy subjects (acquisition time for 23 Na MRI: 18 min; nominal isotropic spatial resolution: 5 mm [kidney] and 6 mm [heart]). CONCLUSION This work provides encouragement for further explorations into densely packed multichannel transceiver arrays tailored for 23 Na MRI of the heart and kidney. Equipped with this technology, the ability to probe sodium concentration in the heart and kidney in vivo using 23 Na MRI stands to make a critical contribution to deciphering the complex interactions between both organs.
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5.
Analyzing the Impact of Bariatric Surgery in Kidney Function: a 2-Year Observational Study.
Magalhães, DSC, Pedro, JMP, Souteiro, PEB, Neves, JS, Castro-Oliveira, S, Bettencourt-Silva, R, Costa, MM, Varela, A, Queirós, J, Freitas, P, et al
Obesity surgery. 2019;(1):197-206
Abstract
BACKGROUND Obesity is an independent risk factor for chronic kidney disease (CKD). Our aims were: (1) to evaluate the impact of bariatric surgery (BS) on kidney function, (2) clarify the factors determining postoperative evolution of glomerular filtration rate (ΔGFR) and urinary albumin-to-creatinine ratio (ΔUACR), and (3) access the occurrence of oxalate-mediated renal complications. METHODS We investigated a cohort of 1448 obese patients who underwent BS. Those with baseline-estimated GFR (eGFR0) < 30 mL/min or without information about the 2-year post-surgical eGFR (eGFR2) were excluded. RESULTS A total of 725 patients were included. At baseline, 38(5.2%) had hyperfiltration with eGFR0 ≥ 125 mL/min/1.73m2 (G0), 492 (67.9%) had eGFR0 90-124 mL/min/1.73m2 (G1), 178 (24.6%) had eGFR0 60-89 mL/min/1.73m2 (G2), and 17 (2.3%) had eGFR0 < 60 mL/min/1.73m2 (G3). ΔGFR significantly increased in 96.6% (ΔGFR = 23.8 (IQR 15.9-29.8)) and 82.4% (ΔGFR = 18.6 (IQR 3.6-44.0)) of the subjects with G2 and G3 CKD, respectively (p < 0.001). The variables independently associated with ΔGFR were baseline body mass index (BMI) (positively), high blood pressure (HBP) (negatively), and fasting plasma glucose (FPG) (negatively), as well as FPG variation (positively). An overall prevalence of high UACR (≥ 30 mg/g-1) of 17.9% was found, with 81.5% of these subjects presenting A2(30-300 mg/g-1) and 18.5% A3(> 300 mg/g-1) UACR. UACR significantly decreased after BS (p < 0.001). Significant predictors of ΔUACR were BMI, systolic blood pressure, and HbA1c. Urinary excretion of calcium oxalate crystals was found in 77(11.1%) patients, with only 1 presenting oxalate-mediated renal complications. CONCLUSIONS ΔGFR seems to be influenced by the initial kidney function, as it decreases in subjects with hyperfiltration but tends to increase in those with kidney dysfunction. These results suggest that BS is associated with improvement of kidney outcomes, without a significant increase in renal complications.
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Denosumab Improves Glomerular Filtration Rate in Osteoporotic Patients With Normal Kidney Function by Lowering Serum Phosphorus.
Miyaoka, D, Inaba, M, Imanishi, Y, Hayashi, N, Ohara, M, Nagata, Y, Kurajoh, M, Yamada, S, Mori, K, Emoto, M
Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. 2019;(11):2028-2035
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Abstract
Higher serum phosphorus (Pi) increases the risk for chronic kidney disease (CKD). It was reported that a single administration of denosumab or zoledronate significantly suppressed serum Pi levels as well as those of bone resorption markers in serum. Also, previous evidences suggest a link between bone anti-resorptive therapy and vasoprotective/renoprotective effects through mechanisms that remain unexplored. The aim of this study is to assess the renoprotective effect of denosumab and involvement of denosumab-induced reduction in serum Pi in osteoporotic patients. Osteoporotic patients (n = 73) without overt proteinuria in dipstick test results were treated with denosumab (60 mg) every 6 months during the study period (24 months). Estimated glomerular filtration rate based on serum cystatin C (eGFRcys) was used as a filtration marker and tartrate-resistant acid phosphatase-5b (TRACP-5b) as a bone resorption marker. For analysis of non-CKD patients (n = 56), those with eGFRcys <60 mL/min/1.73 m2 were excluded. A single injection of denosumab suppressed serum Pi as well as TRACP-5b during the first 6 months, whereas age-related decline in eGFRcys was significantly reversed, with an increase of 2.75 ± 1.2 mL/min/1.73 m2 after 24 months noted. Multivariate analysis showed that serum Pi reduction following the initial denosumab injection was positively associated with serum TRACP-5b suppression during that same period (β = 0.241, p = 0.049). In addition, a positive association of serum Pi suppression, but not of corrected calcium or TRACP-5b, with eGFRcys increase after 24 months (β = 0.321, p = 0.014) was found after adjustments for gender, age, BMI, antihypertensive drug use, albumin, and eGFRcys. The same was observed in osteoporotic cases restricted to non-CKD patients. In conclusion, serum Pi reduction resulting from phosphorus load decrement from bone induced by denosumab is a determinant for eGFRcys increase. Early introduction of bone antiresorptive therapy can retain glomerular filtration in osteoporosis cases, including non-CKD patients. © 2019 American Society for Bone and Mineral Research.
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Comparison between incremental and thrice-weekly haemodialysis: Systematic review and meta-analysis.
Liu, Y, Zou, W, Wu, J, Liu, L, He, Q
Nephrology (Carlton, Vic.). 2019;(4):438-444
Abstract
AIM: Incremental haemodialysis (HD) regimen has recently gained attention. However, its efficacy and safety, compared with conventional thrice-weekly HD, are controversial and previous research results are not convincing. We sought to conduct a meta-analysis to evaluate the benefits and limitations of incremental HD regimen in patients with end-stage renal disease. METHODS We searched PubMed, Embase, and the Cochrane Central Register databases for controlled trials published until January 2017. Outcomes of interest included baseline patient characteristics, mortality risk, renal function, urine volume, laboratory values, and hospitalization rate. RESULTS Overall, 16 studies (n = 252 330), including 15 observational studies and 1 cross-sectional study, were included. Incremental HD reduced mortality risk, compared with conventional HD (risk ratio [RR], 0.797; 95% confidence interval [CI], 0.731-0.870; P < 0.001; I2 = 0%). Renal function (standardized mean difference [SMD] = 0.677, 95% CI: 0.035 to 1.318, P = 0.039; I2 = 92.7%) and urine volume (weighted mean difference [WMD] = 333.37, 95% CI: 86.81 to 579.93, P = 0.008; I2 = 92.7%) were also better preserved in patients on incremental HD. Other clinical outcomes, including serum levels of calcium, phosphate, albumin, haemoglobin, and hospitalization rate, were similar between groups. CONCLUSION An incremental therapeutic approach as a beginning haemodialysis regimen is associated with lower mortality and better preservation of greater residual renal function.
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Association of diabetic retinopathy and diabetic macular oedema with renal function in southern Chinese patients with type 2 diabetes mellitus: a single-centre observational study.
Zhuang, X, Cao, D, Yang, D, Zeng, Y, Yu, H, Wang, J, Kuang, J, Xie, J, Zhang, S, Zhang, L
BMJ open. 2019;(9):e031194
Abstract
BACKGROUND AND OBJECTIVES The association of diabetic retinopathy (DR) and diabetic macular oedema (DME) with renal function in southern Chinese patients with diabetes is poorly understood. So we aimed to study the correlation between stage of DR and DME with stage of estimated glomerular filtration rate (eGFR) and stage of urine albumin-to-creatinine ratio (UACR), and to explore the systemic risk factors for DR and DME. DESIGN AND SETTING This single-centre retrospective observational study was conducted from December 2017 to November 2018. PARTICIPANTS 413 southern Chinese patients with type 2 diabetes mellitus. OUTCOME MEASURES The correlations between stage of DR and DME with stage of eGFR/UACR were assessed by Spearman's or χ² analyses and represented with histograms. Risk factors associated with the occurrence of DR and DME were performed by logistic regression and represented with nomograms. RESULTS Stage of DR had a positive correlation with stage of eGFR (r=0.264, p<0.001) and stage of UACR (r=0.542, p<0.001). With the stage of eGFR/UACR being more severe, the prevalence of DME became higher as well (both p<0.001). The risk factors for DR were DM duration (OR 1.072; 95% CI 1.032 to 1.114; p<0.001), stage of UACR (OR 2.001; 95% CI 1.567 to 2.555; p<0.001) and low-density lipoprotein (LDL) (OR 1.301; 95% CI 1.139 to 1.485; p<0.001), while risk factors for DME were stage of UACR (OR 2.308; 95% CI 1.815 to 2.934; p<0.001) and LDL (OR 1.460; 95% CI 1.123 to 1.875; p=0.008). CONCLUSIONS Among southern Chinese patients, stage of DR and DME were positively correlated with renal function, while stage of UACR performed a better relevance than stage of eGFR.
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Elevated serum anion gap in adults with moderate chronic kidney disease increases risk for progression to end-stage renal disease.
Banerjee, T, Crews, DC, Wesson, DE, McCulloch, CE, Johansen, KL, Saydah, S, Rios Burrows, N, Saran, R, Gillespie, B, Bragg-Gresham, J, et al
American journal of physiology. Renal physiology. 2019;(6):F1244-F1253
Abstract
Acid retention associated with reduced glomerular filtration rate (GFR) exacerbates nephropathy progression in partial nephrectomy models of chronic kidney disease (CKD) and might be reflected in patients with CKD with reduced estimated GFR (eGFR) by increased anion gap (AG). We explored the presence of AG and its association with CKD in 14,924 adults aged ≥20 yr with eGFR ≥ 15 ml·min-1·1.73 m-2 enrolled in the National Health and Nutrition Examination Survey III, 1988-1994, using multivariable regression analysis. The model was adjusted for sociodemographic characteristics, diabetes, and hypertension. We further examined the association between AG and incident end-stage renal disease (ESRD) using frailty models, adjusting for demographics, clinical factors, body mass index, serum albumin, bicarbonate, eGFR, and urinary albumin-to-creatinine ratio by following 558 adults with moderate CKD for 12 yr via the United States Renal Data System. Laboratory measures determined AG using the traditional, albumin-corrected, and full AG definitions. Individuals with moderate CKD (eGFR: 30-59 ml·min-1·1.73 m-2) had a greater AG than those with eGFR ≥ 60 ml·min-1·1.73 m-2 in multivariable regression analysis with adjustment for covariates. We found a graded relationship between the adjusted mean for all three definitions of AG and eGFR categories (P trend < 0.0001). During followup, 9.2% of adults with moderate CKD developed ESRD. Those with AG in the highest tertile had a higher risk of ESRD after adjusting for covariates in a frailty model [relative hazard (95% confidence interval) for traditional AG: 1.76 (1.16-2.32)] compared with those in the middle tertile. The data suggest that high AG, even after adjusting for serum bicarbonate, is a contributing acid-base mechanism to CKD progression in adults with moderate chronic kidney disease.
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Blood Pressure, Chronic Kidney Disease Progression, and Kidney Allograft Failure in Kidney Transplant Recipients: A Secondary Analysis of the FAVORIT Trial.
Malhotra, R, Katz, R, Weiner, DE, Levey, AS, Cheung, AK, Bostom, AG, Ix, JH
American journal of hypertension. 2019;(9):816-823
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Abstract
BACKGROUND In chronic kidney disease, intensive systolic blood pressure (SBP) control reduces mortality at a cost of greater acute kidney injury risk. Kidney transplantation involves implantation of denervated kidneys and immunosuppressive medications that increase acute kidney injury risk. The optimal blood pressure (BP) target in kidney transplant recipients (KTRs) is uncertain. Prior observational studies from the Folic Acid for Vascular Outcome Reduction in Transplantation (FAVORIT) trial demonstrate associations of lower SBP levels and reduced mortality risk, but the relationship of BP with kidney allograft function remains unknown. Thus, in FAVORIT, we investigated the relationship of SBP and diastolic blood pressure (DBP) with risk of kidney allograft failure and estimated glomerular filtration rate (eGFR) slope among stable KTRs. METHODS Cox proportional hazards and multivariable linear regression models adjusted for demographics, transplant characteristics, comorbidities, baseline eGFR, and urine albumin-to-creatinine ratio were used to determine associations of SBP and DBP with time to a composite kidney outcome of ≥50% eGFR decline or dialysis dependence, and with annualized eGFR change, respectively. Multivariable restricted cubic spline plots were developed to evaluate the functional form of the relationships. RESULTS Among 3,598 KTRs, mean age was 52 ± 9 years, SBP was 136 ± 20 mm Hg, DBP was 79 ± 12 mm Hg, and eGFR was 49 ± 18 ml/minute/1.73 m2. There were 369 events of ≥50% eGFR decline or dialysis dependence during a mean follow-up of 4.0 ± 1.5 years. There was no association of either SBP (compared with SBP 120 to <130 mm Hg, hazard ratio (HR) for the SBP < 110 was 1.01 (95% confidence interval (CI) 0.60 to 1.70) and 130 to <140 was 0.89 (0.64 to 1.24)) or DBP (compared with DBP 70 to <80 mm Hg, HR for the DBP 60 to <70 was 1.00 (95% CI 0.74 to 1.34) and 80 to <90 was 0.90 (0.68 to 1.18)) with the kidney failure outcome or annualized eGFR slope, and, when examined using restricted cubic splines, there was no evidence of "J"- or "U"-shaped relationships. CONCLUSIONS In a large sample of stable KTRs, we found no evidence of thresholds at which lower BPs were related to higher risk of allograft failure or eGFR decline. In light of prior findings of mortality benefit at low SBP, these observational findings suggest lower BP may be beneficial in KTRs. This important question requires confirmation in future randomized trials in KTRs.