Role of excess volume in the pathophysiology of hypertension in chronic kidney disease

Nephrotoxic drug burden and predictors of exposure among patients with renal impairment in Ethiopia: A multi-center study

Background

Nephrotoxic drugs may hasten the decline in kidney function and worsen the progression of renal impairment as a result; these drugs should be avoided or used with caution in patients with pre-existing renal insufficiency. The purpose of this study was to assess the burden of nephrotoxic medication use and its predictors among patients with underlying renal impairment.

Methods

A multicenter, institution-based, cross-sectional study was conducted from May 30, 2021 to July 30, 2021, at medical wards. Renal impaired patients admitted during the data collection period who took at least one medication were enrolled in the study. A simple random sampling technique was used to select the study participants. Data was collected through an interview and a medical card review. Both bivariable and multivariable binary logistic regression analyses were fitted to identify factors associated with nephrotoxic drug use.

Results

Among the 422 participants, more than half of them (53.6 %) were male. The mean patient's age was 47.5 (±16.7) years. A total of 1310 drugs were prescribed for 422 patients with renal impairment, of which 80.15 % were nephrotoxic. Nephrotoxic drugs were prescribed for 66.4 % of patients. The burden of nephrotoxic medication prescription was significantly associated with variables like the presence of comorbidity (AOR = 6.31, 95 % CI: 2.01-19.79), the number of medications prescribed (AOR = 1.43, 95 % CI: 1.05-1.93), and the age of participants (AOR = 1.12, 95 % CI: 1.07-1.17).

Conclusion

The present study demonstrated that two-third of the patients with renal impairment were exposed to nephrotoxic medications. Furosemide, Enalapril, and vancomycin were the most frequently prescribed nephrotoxic medications. The study suggests that prescribers need to give special attention to older patients who have underlying renal insufficiency, a comorbid condition, and polypharmacy regarding exposure to contraindicated nephrotoxic medication.

Could admission level of uric acid predict total diuretic dose in acute heart failure?

BACKGROUND

Recent studies have shown that increases in serum UA levels are associated with adverse clinical outcomes in patients with chronic heart failure (CHF); the aim of this study was to determine the relationship between serum uric acid and total diuretic dose received during hospitalization in hospitalized patients with acute exacerbation of heart failure. The main purpose of this study is to determine the role of uric acid as a biomarker that can be a substitute for pro-BNP in clinical evaluation and the need for diuretics in hospitalized patients with acute heart failure.

METHODS

After approving the plan in the Research Council of the Heart Department and obtaining an ethical code from the Regional Committee on Research Ethics (Human Subjects Studies), the researcher referred to the archives of our center, the case of 100 patients diagnosed with acute heart failure. Cardiac patients were selected, and the information required for the study was collected using a pre-prepared data collection form, and the information was entered into SPSS software after categorization and appropriate analysis and statistical tests were performed on it. Were performed and in all statistical tests the statistical significance level was considered 0.05: RESULTS: 100 patients with acute heart failure were included in this study with a mean age of 63.43 ± 14.78 years. 66% of them were men. The mean dose of furosemide in these patients was 680.92 ± 377.47 mg and the mean serum uric acid level in these patients was 8.55 ± 2.50 mg / dL. In the study of the relationship between the variables, there was a significant relationship between the dose of furosemide received with the serum level of serum uric acid (P = 0.017, r = 0.248 and P = 0.009, r = -0.267, respectively). There is also a significant relationship between serum uric acid level and patient mortality (P = 0.013, r = 0.247). However this relationship lost its significance after multivariate analysis.

CONCLUSION

There is a significant relationship between serum uric acid level and diuretic use. However, in-hospital mortality is not related to uric acid levels at admission.

A nationwide cohort study comparing the effectiveness of diuretics and calcium channel blockers on top of renin-angiotensin system inhibitors on chronic kidney disease progression and mortality

It is unknown whether initiating diuretics on top of renin-angiotensin system inhibitors (RASi) is superior to alternative antihypertensive agents such as calcium channel blockers (CCBs) in patients with chronic kidney disease (CKD). For this purpose, we emulated a target trial in the Swedish Renal Registry 2007-2022 that included nephrologist-referred patients with moderate-advanced CKD and treated with RASi, who initiated diuretics or CCB. Using propensity score-weighted cause-specific Cox regression, we compared risks of major adverse kidney events (MAKE; composite of kidney replacement therapy [KRT], experiencing over a 40% eGFR decline from baseline, or an eGFR under 15 ml/min per 1.73m2), major cardiovascular events (MACE; composite of cardiovascular death, myocardial infarction or stroke), and all-cause mortality. We identified 5875 patients (median age 71 years, 64% men, median eGFR 26 ml/min per 1.73m2), of whom 3165 started a diuretic and 2710 a CCB. After a median follow-up of 6.3 years, 2558 MAKE, 1178 MACE and 2299 deaths occurred. Compared to CCB, diuretic use was associated with a lower risk of MAKE (weighted hazard ratio 0.87 [95% confidence interval: 0.77-0.97]), consistent across single components (KRT: 0.77 [0.66-0.88], over 40% eGFR decline: 0.80 [0.71-0.91] and eGFR under 15ml/min/1.73m2: 0.84 [0.74-0.96]). The risks of MACE (1.14 [0.96-1.36]) and all-cause mortality (1.07 [0.94-1.23]) did not differ between therapies. Results were consistent when modeling the total time drug exposure, across sub-groups and a broad range of sensitivity analyses. Thus, our observational study suggests that in patients with advanced CKD, using a diuretic rather than a CCB on top of RASi may improve kidney outcomes without compromising cardioprotection.

Renin-Angiotensin Inhibition and Outcomes in HFrEF and Advanced Kidney Disease

BACKGROUND

Renin-angiotensin system inhibitors improve outcomes in patients with heart failure with reduced ejection fraction (HFrEF). However, less is known about their effectiveness in patients with HFrEF and advanced kidney disease.

METHODS

In the Medicare-linked Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure (OPTIMIZE-HF), 1582 patients with HFrEF (ejection fraction ≤40%) had advanced kidney disease (estimated glomerular filtration rate <30 mL/min/1.73 m2). Of these, 829 were not receiving angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) prior to admission, of whom 214 were initiated on these drugs prior to discharge. We calculated propensity scores for receipt of these drugs for each of the 829 patients and assembled a matched cohort of 388 patients, balanced on 47 baseline characteristics (mean age 78 years; 52% women; 10% African American; 73% receiving beta-blockers). Hazard ratios (HR) and 95% confidence intervals (CI) were estimated comparing 2-year outcomes in 194 patients initiated on ACE inhibitors or ARBs to 194 patients not initiated on those drugs.

RESULTS

The combined endpoint of heart failure readmission or all-cause mortality occurred in 79% and 84% of patients initiated and not initiated on ACE inhibitors or ARBs, respectively (HR associated with initiation, 0.79; 95% CI, 0.63-0.98). Respective HRs (95% CI) for the individual endpoints of - Respective HRs (95% CI) for the individual endpoints of all-cause mortality and heart failure readmission were 0.81 (0.63-1.03) and 0.63 (0.47-0.85).

CONCLUSIONS

The findings from our study add new information to the body of cumulative evidence that suggest that renin-angiotensin system inhibitors may improve clinical outcomes in patients with HFrEF and advanced kidney disease. These hypothesis-generating findings need to be replicated in contemporary patients.

Therapeutic roles of thiazides and loop diuretics in blood pressure control and renal protection against chronic kidney disease

Fluid overload secondary to loss of functional nephron mass can elevate blood pressure, which is characteristic of hypertension shown in chronic kidney disease (CKD). Therefore, it is logical to use diuretics at appropriate dose to lower blood pressure in patients with CKD and hypertension. Despite the theoretical background on the use of diuretics in CKD, there have been no definitive data on the effectiveness or safety of diuretics as first-line therapy for the management of hypertension in patients with CKD. Results from some clinical trials have demonstrated that diuretics would not lower blood pressure. They could even worsen electrolyte imbalance and kidney function when they are administered in patients with CKD. Major clinical practice guidelines on management of blood pressure or CKD have stated that evidence for benefits of thiazide diuretics is not conclusive yet in patients with advanced CKD, although loop diuretics are often effective for volume control at lower glomerular filtration rate. Recently, evidence for diuretics as effective blood pressure lowering agents in patients with advanced CKD is increasing. Renoprotective effect of thiazide or loop diuretics might represent a consequence of their influence on blood pressure or their ability to potentiate the effect of renin-angiotensin system blockade by making intraglomerular pressure more renin-angiotensin system-dependent, although their direct benefit on renal function remains controversial. This review summarizes recent data on the possible role of diuretics in lowering blood pressure, slowing the progression of kidney disease, and reducing cardiovascular risk in CKD patients.

The Dropsy of Popes (1555-1978): A Bad Prognostic Sign Foreboding of Death

The purpose of this study is to explore the historical background of edema as a prognostic sign in popes, a special category of medical subjects whose health status was closely monitored and chronicled because of their unique important status in the events of their times. Nine out of 51 popes, who reigned in the years 1555-1978, died edematous at a mean age of 75.5 years of age. The cause of edema was: heart failure for John Paul I, liver disease, obstructive nephropathy associated with anemia for Paul IV, who also suffered from deep vein thrombosis, and malnutrition for Innocent XIII. Chronic kidney disease due to renal stones of gouty origin caused edema in Clement VIII, Clement X, Clement XI, and Benedict XIV. Obstructive nephropathy due to renal stones of non-gouty origin caused edema in Clement XIII, whereas toxic nephropathy due to the use of mercurials caused edema in Clement XIV. Innocent XI, Benedict XIV, and Clement XIV were bled before death because of impending pulmonary edema. It is not surprising that chronic kidney disease was a significant cause of edema in popes with chronic kidney disease which is associated with impaired sodium excretion. The edema was likely aggravated by the excessive dietary salt intake of the period when the importance of sodium chloride restriction was still not discovered and effective diuretic agents were not available.

Applications of cardiac biomarkers in chronic kidney disease

PURPOSE OF REVIEW

Cardiovascular disease is the leading cause of death in individuals with chronic kidney disease (CKD). The mechanisms connecting CKD and cardiovascular disease are complex, and serum biomarkers can help improve our understanding. Nt-proBNP and troponin have documented success as biomarkers to diagnose and provide mechanistic insights in non-CKD populations. The purpose of this review is to summarize evidence suggesting efficacy and potential for clinical application of Nt-proBNP and troponin in individuals with CKD.

RECENT FINDINGS

Our understanding of how Nt-proBNP and Troponin should be interpreted in those with CKD is evolving. Although both biomarkers are in part cleared by the kidney, elevated levels predominantly reflect cardiovascular disease. Both Nt-proBNP and troponin are associated with risk for future cardiovascular events in CKD. Determining CKD-specific cutoffs and using biomarkers to guide therapy remains under active investigation.

SUMMARY

Of the many serum biomarkers under investigation, Nt-proBNP and troponin best meet the criteria for effective biomarkers in CKD. Assays are widely available and proven to be accurate in CKD populations. Nt-proBNP and troponin deserve special focus in ongoing research of cardiovascular risk reduction in CKD, especially to identify patients at the highest risk, suggest targetable mechanisms and assess treatment efficacy.

Effect of diuretics on plasma renin activity in primary hypertension: A systematic review and meta-analysis

AIMS

Plasma renin activity (PRA) is regarded as a marker of sodium and fluid homeostasis in patients with primary hypertension. Whether effects of diuretics on PRA differ according to class of diuretic, whether diuretics lead to a sustained increase in PRA, and whether changes in PRA relate to those in blood pressure (BP) is unknown. We performed a systematic review and meta-analysis of trials investigating the antihypertensive effects of diuretic therapy in which PRA and/or other biomarkers of fluid homeostasis were measured before and after treatment.

METHODS

Three databases were searched: MEDLINE, EMBASE and The Cochrane Central Register of Controlled Trials. Titles were firstly screened by title and abstract for relevancy before full-text articles were assessed for eligibility according to a predefined inclusion/exclusion criteria.

RESULTS

A total of 1684 articles were retrieved of which 61 met the prespecified inclusion/exclusion criteria. PRA was measured in 30/61 studies. Diuretics led to a sustained increase in PRA which was similar for different classes of diuretic (standardised mean difference [95% confidence interval] 0.481 [0.362, 0.601], 0.729 [0.181, 1.28], 0.541 [0.253, 0.830] and 0.548 [0.159, 0.937] for thiazide, loop, mineralocorticoid receptor antagonists/potassium-sparing and combination diuretics respectively, Q = 0.897, P = .826), and did not relate to the average decrease in blood pressure.

CONCLUSION

In antihypertensive drug trials, diuretics lead to a sustained increase in average PRA, which is similar across different classes of diuretic and unrelated to the average reduction in blood pressure.

Trajectory of extracellular fluid volume over time and subsequent risks of end-stage kidney disease and mortality in chronic kidney disease: a prospective cohort study

BACKGROUND

Extracellular fluid volume (ECF) is independently associated with chronic kidney disease (CKD) progression and mortality in patients with CKD, but the prognostic value of the trajectory of ECF over time beyond that of baseline value is unknown.

OBJECTIVES

To characterize ECF trajectory and evaluate its association with the risks of end-stage kidney disease (ESKD) and mortality.

METHODS

From the prospective tricentric NephroTest cohort, we included 1588 patients with baseline measured glomerular filtration rate (mGFR) ≥15 mL min^-1 /1.73 m² and ECF measurement. ECF and GFR were measured repeatedly using the distribution volume and clearance of ⁵¹ Cr-EDTA, respectively. ESKD and mortality were traced through record linkage with the national registries. Adjusted shared random-effect joint models were used to analyse the association between the trajectory of ECF over time and the two competing outcomes.

RESULTS

Patients were mean age 58.7 years, 66.7% men, mean mGFR of 43.6 ± 18.6 mL min^-1 /1.73 m² and mean ECF of 16.1 ± 3.6 L. Over a median follow-up of 5.3 [IQR: 3.0;7.4] years, ECF increased by 136 [95%CI 106;167] mL per year on average, whilst diuretic prescription and 24-hour urinary sodium excretion remained stable. ESKD occurred in 324 (20.4%) patients, and 185 (11.6%) patients died before ESKD. A higher current value of ECF was associated with increased hazards of ESKD (adjusted hazard ratio [aHR]: 1.12 [95%CI 1.06;1.18]; P < 0.001 per 1 L increase in ECF), and death before ESKD (aHR: 1.10 [95%CI 1.04;1.17]; P = 0.002).

CONCLUSIONS

The current value of ECF was associated with the risks of ESKD and mortality, independent of multiple potential confounders, including kidney function decline. This highlights the need for a close monitoring and adjustment of treatment to avoid fluid overload in CKD patients.

Genetic susceptibility of hypertension-induced kidney disease

Hypertension is the second leading cause of end-stage renal disease (ESRD) after diabetes mellitus. The significant differences in the incidence of hypertensive ESRD between different patient populations worldwide and patients with and without family history indicate that genetic determinants play an important role in the onset and progression of this disease. Recent studies have identified genetic variants and pathways that may contribute to the alteration of renal function. Mechanisms involved include affecting renal hemodynamics (the myogenic and tubuloglomerular feedback responses); increasing the production of reactive oxygen species in the tubules; altering immune cell function; changing the number, structure, and function of podocytes that directly cause glomerular damage. Studies with hypertensive animal models using substitution mapping and gene knockout strategies have identified multiple candidate genes associated with the development of hypertension and subsequent renal injury. Genome-wide association studies have implicated genetic variants in UMOD, MYH9, APOL-1, SHROOM3, RAB38, and DAB2 have a higher risk for ESRD in hypertensive patients. These findings provide genetic evidence of potential novel targets for drug development and gene therapy to design individualized treatment of hypertension and related renal injury.

Volume Balance in Chronic Kidney Disease: Evaluation Methodologies and Innovation Opportunities

BACKGROUND

Patients affected by chronic kidney disease are at a risk of cardiovascular morbidity and mortality. Body fluids unbalance is one of the main characteristics of this condition, as fluid overload is highly prevalent in patients affected by the cardiorenal syndrome.

SUMMARY

We describe the state of the art and new insights into body volume evaluation. The mechanisms behind fluid balance are often complex, mainly because of the interplay of multiple regulatory systems. Consequently, its management may be challenging in clinical practice and even more so out-of-hospital. Availability of novel technologies offer new opportunities to improve the quality of care and patients' outcome. Development and validation of new technologies could provide new tools to reduce costs for the healthcare system, promote personalized medicine, and boost home care. Due to the current COVID-19 pandemic, a proper monitoring of chronic patients suffering from fluid unbalances is extremely relevant. Key Message: We discuss the main mechanisms responsible for fluid overload in different clinical contexts, including hemodialysis, peritoneal dialysis, and heart failure, emphasizing the potential impact provided by the implementation of the new technologies.

Furosemide as a factor to deteriorate therapeutic efficacy of rifaximin in patients with decompensated cirrhosis

AIM

To optimize the therapeutic strategy for cirrhotic patients manifesting hepatic encephalopathy, factors affecting the outcome of patients receiving rifaximin were evaluated.

METHODS

The subjects were 95 patients receiving rifaximin. Serum ammonia levels were measured serially during rifaximin treatment. Factors associated with long-term outcomes and cumulative survival rates were evaluated.

RESULTS

Serum ammonia levels were decreased at 4 weeks after rifaximin treatment compared to the levels at baseline even in patients receiving rifaximin as an add-on therapy with lactitol hydrate (P < 0.001) and reduction values were negatively correlated with the maximal diameter of portosystemic shunts (r = -0.275, P = 0.009). Overt encephalopathy occurred in 37 patients (38.9%) during rifaximin treatment, and the hazard function analysis identified 90 days as a high-risk term for developing the first-time overt encephalopathy. Thus, the long-term outcome was judged as favorable in 77 patients (81.1%) in whom overt encephalopathy was absent for at least 90 days during rifaximin initiation. A multivariate analysis revealed that furosemide, especially at daily doses of ≥20 mg both at baseline and during rifaximin treatment, was a significant factor associated with unfavorable outcome (P = 0.009 and P = 0.022, respectively) as well as occurrence and recurrence of overt encephalopathy (P = 0.012). Moreover, furosemide treatment significantly deteriorated the cumulative survival rate of patients receiving rifaximin (P = 0.026).

CONCLUSION

Furosemide contributed to the deteriorated outcome of patients receiving rifaximin. Consequently, rifaximin should be given before increasing the furosemide dose, and the furosemide dose should not be increased during rifaximin treatment.

Associations of blood biomarkers with glomerular filtration rate in patients with TIA and stroke: population-based study

Background and purpose

Non-traditional risk factors such as chronic inflammation, oxidative stress and thrombogenic factors are believed to contribute to the excess stroke risk in chronic kidney disease (CKD) by triggering vascular injury and endothelial dysfunction. We aimed to determine how well a panel of biomarkers representative of these factors would correlate with estimated glomerular filtration rate (eGFR) in patients with recent transient ischaemic attack (TIA) or stroke. We also investigated whether eGFR would confound previously reported associations between biomarkers and mortality.

Methods

We studied a panel of 16 blood biomarkers related to inflammation, thrombosis, atherogenesis and cardiac or neuronal cell damage in TIA or ischaemic stroke in a population-based study (Oxford Vascular Study). Biomarker levels were log-transformed and correlated with eGFR, adjusted for age. Cox proportional hazard models were used for survival analysis.

Results

Among 1297 patients with TIA or stroke, 52.7% (n=684) of patients had CKD (eGFR <60 mL/min/1.73 m²). There was a moderate correlation between log-eGFR and the log-transformed soluble tumour necrosis factor receptor-1 (R²=0.21), attenuating with adjustment for age (R²=0.12). There were moderate-to-strong correlations with markers of cardiac injury, N-terminal pro-brain natriuretic peptide and heart-type fatty acid binding protein (hFABP, R²=0.14 and 0.34, respectively). The strongest correlation after adjustment for age was between hFABP and eGFR (R²=0.20). Adjusting for eGFR did not impact any biomarker associations with mortality.

Conclusions

Correlations between biomarkers related to inflammation and thrombosis with renal dysfunction in the setting of cerebrovascular events were generally modest after adjustment for age, suggesting that putative risk factors such as chronic inflammation or coagulopathy are unlikely to be important stroke mechanisms in patients with CKD.

Resistant Hypertension: Where are We Now and Where Do We Go from Here?

Resistant hypertension is an important subtype of hypertension that leads to an increased risk of cerebrovascular, cardiovascular, and kidney disease. The revised guidelines from the American College of Cardiology and American Heart Association now define resistant hypertension as blood pressure that remains above goal despite use of three maximally titrated anti-hypertensive medications including a diuretic or as a hypertensive patient who requires 4 or more agents for adequate BP control. These agents typically include a calcium-channel blocker, a renin-angiotensin system inhibitor, and a diuretic at maximal or maximally tolerated doses. As recognition of resistant hypertension increases, it is important to distinguish pseudo-resistant or apparent hypertension from true resistant hypertension. Etiologies of apparent resistant hypertension include measurement error and medication non-adherence. The prevalence of true resistant hypertension is likely much lower than reported in the literature when accounting for patients with apparent resistant hypertension. Evaluation of patients with true resistant hypertension includes screening for causes of secondary hypertension and interfering medications. Successful management of resistant hypertension includes lifestyle modification and optimization of medical therapy, often including the use of mineralocorticoid receptor antagonists. Looking ahead at developments in hypertension management, a slew of new device-based therapies are under active development. Of these, renal denervation is the closest to routine clinical application. Further study is needed before these devices can be recommended in the routine treatment of resistant hypertension.

Extracellular fluid volume expansion, arterial stiffness and uncontrolled hypertension in patients with chronic kidney disease

BACKGROUND

Hypertension is prevalent in patients with chronic kidney disease (CKD) and is related to extracellular fluid volume (ECFV) expansion. Arterial stiffening is another implication of CKD that can be caused by ECFV expansion. In this study, we hypothesized that CKD patients with uncontrolled hypertension are more likely to be fluid volume expanded than normotensive patients, which in turn is associated with increased arterial stiffness.

METHODS

Adult hypertensive patients with mild-severe CKD (n = 82) were recruited. ECFV was assessed using multifrequency bioimpedance and arterial stiffness by applanation tonometry and oscillometry.

RESULTS

Patients with uncontrolled hypertension had fluid volume expansion compared with controls (1.0 ± 1.5 versus 0.0 ± 1.6 L, P < 0.001), and had a higher augmentation index (AIx) and pulse wave velocity. Fluid volume expansion was more prevalent in patients with uncontrolled hypertension (58%) than patients who were at target (27%). Fluid volume expansion was correlated with age, AIx and systolic blood pressure. In a binary logistic regression analysis, AIx, age and fluid volume status were independent predictors of uncontrolled hypertension in both univariate and multivariate models.

DISCUSSION

In summary, uncontrolled hypertension among hypertensive CKD patients is associated with ECFV expansion. Our data suggest a relationship between ECFV expansion, increased arterial stiffness and uncontrolled hypertension.

Diuretic Resistance in Heart Failure

Purpose of review:

Diuretic resistance (DR) occurs along a spectrum of relative severity and contributes to worsening of acute heart failure (AHF) during an inpatient stay. This review gives an overview of mechanisms of DR with a focus on loop diuretics and summarizes the current literature regarding the prognostic value of diuretic efficiency and predictors of natriuretic response in AHF.

Recent findings:

The pharmacokinetics of diuretics are impaired in chronic heart failure, but little is known about mechanisms of DR in AHF. Almost all diuresis after administration of a loop diuretic dose occurs in the first few hours after administration and within-dose DR can develop. Recent studies suggest that DR at the level of the nephron may be more important than defects in diuretic delivery to the tubule. Because loop diuretics induce natriuresis, urine sodium (UNa) concentration may serve as a functional, physiologic and direct measure for diuretic responsiveness to a given loop diuretic dose.

Summary:

Identifying and targeting individuals with DR for more aggressive, tailored therapy represents an important opportunity to improve outcomes. A better understanding of the mechanistic underpinnings of DR in AHF is needed to identify additional biomarkers and guide future trials and therapies.

Cardiovascular Protection of Nephropathic Male Patients by Oral Food Supplements

Nephropathic patients show elevated cardiovascular morbidity and mortality compared to the general population. In order to delve deeper into the understanding of this phenomenon, it is necessary to recognize risk factors that are distinctive to the uremic state, such as oxidative stress and chronic low-grade inflammation. Moreover, gender differences have been reported in nephrology, as it has been observed that chronic kidney disease has higher prevalence in males than in females. The use of an oral food supplement (OFS) containing natural active compounds from Capsicum annuum L., Garcinia cambogia, Centella asiatica L., artichoke, and Aesculus hippocastanum L. which are virtually devoid from side effects, but rich in antioxidant and antiradical properties, could represent a valid therapeutic adjunct in the clinical management of nephropathic patients. Moreover, quantitative analysis performed in vitro on such compounds showed that they expressed good total antioxidant (7.28 gallic acid equivalents) and antiradical activity (above 80%). In this study, 23 male nephropathic patients and 10 age and body composition parameter matched healthy males (control group) were enrolled and took 3 cps/day of OFS for 5 weeks. At the end of the study, the nephropathic patient group showed a statistically significant reduction in the following laboratory parameters: total cholesterol (TC) (p = 0.044), atherogenic index TC/high-density lipoprotein cholesterol (p = 0.010), inflammatory parameters (C-reactive protein, p = 0.048, and erythrocyte sedimentation rate, p = 0.019), systolic (p = 0.044), and diastolic arterial blood pressure (p = 0.003). Regarding body composition, there was an increase in total body water % (p = 0.035) with redistribution of extracellular water % (p = 0.030) and intracellular water % (p = 0.049). In the control group, there was a reduction in fat mass % (p = 0.017) and extracellular water % (p = 0.047). Therefore, this OFS may represent a valid adjunct therapy to counteract comorbidities related to uremia.

The extracellular volume status predicts body fluid response to SGLT2 inhibitor dapagliflozin in diabetic kidney disease

BACKGROUND

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are an antihyperglycemic drug with diuretic action. We recently reported that the SGLT2 inhibitor dapagliflozin ameliorates extracellular volume expansion with a mild increase in urine volume. However, the impact of the pretreatment extracellular volume status on the body fluid response to SGLT2 inhibitors remains unclear.

METHODS

Thirty-six diabetic kidney disease (DKD) patients were treated with dapagliflozin. The body fluid volume, including intracellular water (ICW), extracellular water (ECW) and total body water (TBW), were measured on baseline and day 7 using a bioimpedance analysis (BIA) device. The ECW/TBW and ECW were used as markers of the extracellular volume status. For a comparison, the extracellular volume status responses to loop diuretic furosemide (n = 16) and vasopressin V2 receptor antagonist tolvaptan (n = 13) were analyzed.

RESULTS

The body weight, brain natriuretic peptide and body fluid parameters measured by a BIA (ICW, ECW, TBW, and ECW/TBW) were significantly decreased for 1 week after dapagliflozin administration. The change in the ECW/TBW in the high-ECW/TBW group (over the median value of 0.413) was significantly higher than in the low-ECW/TBW group (- 2.1 ± 0.4 vs. - 0.5 ± 0.4%, p = 0.006). Only with dapagliflozin treatment (not furosemide or tolvaptan treatment) was the baseline ECW/TBW significantly correlated with the changes in the ECW/TBW (r = - 0.590, p < 0.001) and ECW (r = - 0.374, p = 0.025).

CONCLUSIONS

The pretreatment extracellular volume status predicts the body fluid response to the SGLT2 inhibitor dapagliflozin in DKD patients. The diminished extracellular fluid reduction effect of dapagliflozin in patients without severe extracellular fluid retention may contribute to maintaining a suitable body fluid status.

Extracellular Fluid Volume Is an Independent Determinant of Uncontrolled and Resistant Hypertension in Chronic Kidney Disease: A NephroTest Cohort Study

Background

Hypertension is highly prevalent during chronic kidney disease (CKD) and, in turn, worsens CKD prognosis. We aimed to describe the determinants of uncontrolled and resistant hypertension during CKD.

Methods and Results

We analyzed baseline data from patients with CKD stage 1 to 5 (NephroTest cohort) who underwent thorough renal explorations, including measurements of glomerular filtration rate (clearance of ⁵¹Cr‐EDTA) and of extracellular water (volume of distribution of the tracer). Hypertension was defined as blood pressure (BP; average of 3 office measurements) ≥140/90 mm Hg or the use of antihypertensive drugs. In 2015 patients (mean age, 58.7±15.3 years; 67% men; mean glomerular filtration rate, 42±15 mL/min per 1.73 m²), prevalence of hypertension was 88%. Among hypertensive patients, 44% and 32% had uncontrolled (≥140/90 mm Hg) and resistant (uncontrolled BP despite 3 drugs, including a diuretic, or ≥4 drugs, including a diuretic, regardless of BP level) hypertension, respectively. In multivariable analysis, extracellular water, older age, higher albuminuria, diabetic nephropathy, and the absence of aldosterone blockers were independently associated with uncontrolled BP. Extracellular water, older age, lower glomerular filtration rate, higher albuminuria and body mass index, male sex, African origin, diabetes mellitus, and diabetic and glomerular nephropathies were associated with resistant hypertension.

Conclusions

In this large population of patients with CKD, a lower glomerular filtration rate, a higher body mass index, diabetic status, and African origin were associated with hypertension severity but not with BP control. Higher extracellular water, older age, and higher albuminuria were independent determinants of both resistant and uncontrolled hypertension during CKD. Our results advocate for the large use of diuretics in this population.

Extracellular fluid volume is associated with incident end-stage kidney disease and mortality in patients with chronic kidney disease

Volume overload has been shown to be an independent risk factor for mortality in patients receiving chronic dialysis, but data in non-dialysis patients are scarce. Therefore we evaluated the prognostic value of extracellular fluid (ECF) volume for chronic kidney disease (CKD) progression and mortality in a prospective hospital-based cohort with CKD stage 1-4 (NephroTest Study). ECF (scaled to body surface area) and the measured glomerular filtration rate (mGFR) were determined using the distribution volume and clearance of 51Cr-EDTA, respectively. Cause-specific Cox and linear mixed-effect regression models were used to analyze the association of ECF with end-stage kidney disease (ESKD) and mortality, and with mGFR decline, respectively. The 1593 patients were mean age 58.8 years, 67% were men, mean mGFR of 43.6 mL/min/1.73m² and mean ECF 15.1 L/1.73m². After a median follow-up of 5.3 years, ESKD occurred in 324 patients and 185 patients died before ESKD. In multivariable analysis, ECF was significantly associated with the risk of ESKD (hazard ratio per 1L/1.73m² increase: 1.14; 95% confidence interval [1.07; 1.21]) and with a faster GFR decline (adjusted mean difference in mGFR slope per 1L/1.73m² increase -0.14 [-0.23; -0.05] mL/min/year). The relationship of ECF with mortality was non-linear and not significant (per 1L/1.73m² increase 0.92, [0.73; 1.16]), below 15L/1.73m², but significant (1.28; [1.14-1.45]) above 15L/1.73m². Thus, in this large cohort of carefully phenotyped patients with CKD, ECF was an independent risk factor of CKD progression and mortality. Hence, close monitoring and treatment of fluid overload are important for the clinical management of patients with non-dialysis CKD.

Different Effects on Fluid Distribution between Tolvaptan and Furosemide in a Liver Cirrhosis Patient with Chronic Kidney Disease

A 73-year-old man with liver cirrhosis and advanced chronic kidney disease was admitted to our hospital due to bilateral lower leg edema and appetite loss. Furosemide to treat fluid retention markedly decreased extracellular water compared with intracellular water, but the addition of tolvaptan equally decreased both with a greater diuretic response than furosemide alone. Furthermore, tolvaptan administration increased the plasma colloid osmotic pressure, which might facilitate the shift of fluid from the extravascular space to the intravascular space. This is the first case showing different effects on the fluid distribution between furosemide and additional tolvaptan in the same patient.

Effects of the sodium-glucose cotransporter 2 inhibitor dapagliflozin on fluid distribution: A comparison study with furosemide and tolvaptan

AIM

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are an antihyperglycemic drug with diuretic properties. We recently reported that an SGLT2 inhibitor ameliorated extracellular fluid expansion with a transient increase in urinary Na⁺ excretion. However, the effects of SGLT2 inhibitors on fluid distribution in comparison to conventional diuretics remain unclear.

METHODS

Forty chronic kidney disease patients with fluid retention (average estimated glomerular filtration rate 29.2 ± 3.2 mL/min per 1.73 m² ) were divided into the SGLT2 inhibitor dapagliflozin (DAPA), loop diuretic furosemide (FR) and vasopressin V2 receptor antagonist tolvaptan (TLV). The body fluid volume was measured on days 0 and 7 using a bioimpedance analysis device.

RESULTS

In all three groups, body weight was significantly and similarly decreased, and urine volume numerically increased for 7 days. Bioimpedance analysis showed that the changes in intracellular water were similar, but that there were significant changes in the extracellular water (ECW) (DAPA -8.4 ± 1.7, FR -12.5 ± 1.3, TLV -7.4 ± 1.5%, P = 0.048). As a result, the change in the ratio of ECW to total body water in the DAPA group was significantly smaller than that in the FR group, but numerically larger than that in the TLV group (DAPA -1.5 ± 0.5, FR -3.6 ± 0.5, TLV -0.5 ± 0.4%, P < 0.001).

CONCLUSION

Sodium-glucose cotransporter 2 inhibitor DAPA predominantly decreased the ECW with a mild increase in urine volume, but the change in the ECW/total body water was smaller than that in patients treated with FR, and larger than that in patients treated with TLV, suggesting that the effects of SGLT2 inhibitors on fluid distribution may differ from those of conventional diuretics.

Risk factors for vancomycin nephrotoxicity and time course of renal function during vancomycin treatment

PURPOSE

Vancomycin (VCM) is used for the treatment of methicillin-resistant Staphylococcus aureus. Although the risk factors for VCM nephrotoxicity have been evaluated, the time course of renal function during VCM treatment is unknown. We assessed risk factors for VCM nephrotoxicity and how renal function varied over time.

METHODS

We conducted a retrospective analysis of patients receiving intravenous VCM treatment between June 2015 and August 2017 at Tokyo Women's Medical University, Medical Center East. VCM nephrotoxicity was defined as an increase in serum creatinine levels > 50%. We performed multivariate logistic regression analysis to assess risk factors for VCM nephrotoxicity. The time course of renal function with VCM nephrotoxicity was compared and stratified by risk factors for VCM nephrotoxicity. Clinical course of VCM nephrotoxicity and VCM trough concentration were assessed.

RESULTS

In total, 42 (17.3%) of 243 patients developed VCM nephrotoxicity. Risk factors for VCM nephrotoxicity were VCM trough concentration > 20 μg/mL and concomitant use of renal hypoperfusion medications (angiotensin-converting enzyme inhibitor/angiotensin receptor blocker, loop/thiazide diuretics, and non-steroidal anti-inflammatory drugs). Although time course of renal function stratified by renal hypoperfusion medications was comparable, the time course of renal function significantly deteriorated in patients with loop/thiazide diuretics. Focusing on patients continuing VCM treatment, VCM nephrotoxicity recovered in 40% of the patients and VCM trough concentration improved to 10-20 μg/mL in 75% of the patients.

CONCLUSIONS

VCM trough concentration > 20 μg/mL and concomitant use of renal hypoperfusion medications are associated with VCM nephrotoxicity. Recovery of VCM nephrotoxicity was poor compared to the improvement of VCM trough concentration.

Sodium and Fluid Excretion With Torsemide in Healthy Subjects is Limited by the Short Duration of Diuretic Action

BACKGROUND

Loop diuretics are highly natriuretic but their short duration of action permits postdiuretic sodium retention, which limits salt loss unless dietary salt is severely restricted. We tested the hypothesis that a more prolonged duration of action would enhance salt loss.

METHODS AND RESULTS

Ten healthy participants were crossed over between 20 mg of oral immediate-release or extended-release (ER) torsemide while consuming a fixed diet with 300 mmol·d^-1 of Na⁺. Compared with immediate-release, plasma torsemide after ER was 59% lower at 1 to 3 hours but 97% higher at 8 to 10 hours as a result of a >3-fold prolongation of time to maximal plasma concentrations. The relationship of natriuresis to log torsemide excretion showed marked hysteresis, but participants spent twice as long with effective concentrations of torsemide after ER, thereby enhancing diuretic efficiency. Compared with immediate-release, ER torsemide did not reduce creatinine clearance and increased fluid (1634±385 versus 728±445 mL, P<0.02) and Na⁺ output (98±15 versus 42±17 mmol, P<0.05) despite an 18% reduction in exposure. Neither formulation increased K⁺ excretion.

CONCLUSIONS

Torsemide ER prolongs urine drug levels, thereby increasing the time spent with effective drug concentrations, reduces postdiuretic Na⁺ retention, and moderates a fall in glomerular filtration rate. It caused significant Na⁺ loss even during very high salt intake. Thus, a short duration of action limits salt loss with loop diuretics. These conclusions warrant testing in subjects with edema and heart failure.

Treatment of Disorders of Sodium Balance in Chronic Kidney Disease

Extracellular fluid volume expansion is nearly universal in patients with CKD. Such volume expansion has features similar to the syndrome of heart failure with preserved ejection fraction, which not only leads to symptoms but can also lead to further organ damage. Unique treatment challenges are present in this patient population, including low glomerular filtration, which limits sodium chloride filtration, intrinsic tubule predisposition to sodium chloride retention, and proteinuria. In addition, pharmacokinetic considerations alter the disposition of diuretics in patients with CKD and nephrotic syndrome. Maintaining extracellular fluid volume near to normal is often necessary for hypertension treatment in this population, but it may also help prevent progressive cardiovascular and kidney damage. Although powerful diuretics can often accomplish this goal, this often comes at a cost of competing adverse effects. An approach to reduce extracellular fluid volume while avoiding adverse effects, therefore, requires a nuanced yet aggressive therapeutic approach.

Hypertension in pediatric patients with chronic kidney disease: management challenges

In contrast to adults where hypertension is a leading cause of chronic kidney disease, in pediatrics, hypertension is predominantly a sequela, however, an important one that, like in adults, is likely associated with a more rapid decline in kidney function or progression of chronic kidney disease to end stage. There is a significant issue with unrecognized, or masked, hypertension in childhood chronic kidney disease. Recent evidence and, therefore, guidelines now suggest targeting a blood pressure of <50th percentile for age, sex, and height in children with proteinuria and chronic kidney disease. This often cannot be achieved by monotherapy and additional agents need to be added. Blockade of the renin angiotensin aldosterone system represents the mainstay of therapy, although often limited by the side effect of hyperkalemia. The addition of a diuretic, at least in the earlier stages of chronic kidney disease, might help mitigate this problem.

Outcomes of diuretic use in pre-dialysis CKD patients with moderate renal deterioration attending tertiary care referral center

INTRODUCTION

Diuretic therapy has been the mainstay of treatment in chronic kidney disease (CKD) patients, primarily for hypertension and fluid overload. Apart from their beneficial effects, diuretic use is associated with adverse renal outcomes. The current study is aimed to determine the outcomes of diuretic therapy.

METHODOLOGY

A prospective observational study was conducted by inviting pre-dialysis CKD patients. Fluid overload was assessed by Bioimpedance analysis (BIA).

RESULTS

A total 312 patients (mean age 64.5 ± 6.43) were enrolled. Among 144 (46.1%) diuretic users, furosemide and hydrochlorothiazide (HCTZ) were prescribed in 69 (48%) and 39 (27%) patients, respectively, while 36 (25%) were prescribed with combination therapy (furosemide plus HCTZ). Changes in BP, fluid compartments, eGFR decline and progression to RRT were assessed over a follow-up period of 1 year. Maximum BP control was observed with combination therapy (-19.3 mmHg, p < 0.001) followed by furosemide [-10.6 mmHg with 80 mg thrice daily (p < 0.001)], -9.3 mmHg with 40-60 mg (p < 0.001) and -5.9 mmHg with 20-40 mg (p = 0.02) while HCTZ offered minimal SBP control [-3.7 mmHg with 12.5-25 mg (p = 0.04)]. Decline in extracellular water (ECW) ranged from -1.5 L(p = 0.01) with thiazide diuretics to -3.8 L(p < 0.001) with combination diuretics. Decline in eGFR was maximum (-3.4 ml/min/1.73 m², p = 0.01) with combination diuretics and least with thiazide diuretics (-1.6 ml/min/1.73 m², p = 0.04). Progression to RRT was observed in 36 patients.

CONCLUSION

It is cautiously suggested to discourage the use of diuretic combination therapy and high doses of single diuretic therapy. Prescribing of diuretics should be done by keeping in view benefit versus harm for each patient.

Recognition and Management of Resistant Hypertension

Despite improvements in hypertension awareness and treatment, 30%-60% of hypertensive patients do not achieve BP targets and subsequently remain at risk for target organ damage. This therapeutic gap is particularly important to nephrologists, who frequently encounter treatment-resistant hypertension in patients with CKD. Data are limited on how best to treat patients with CKD and resistant hypertension, because patients with CKD have historically been excluded from hypertension treatment trials. First, we propose a consistent definition of resistant hypertension as BP levels confirmed by both in-office and out-of-office measurements that exceed appropriate targets while the patient is receiving treatment with at least three antihypertensive medications, including a diuretic, at dosages optimized to provide maximum benefit in the absence of intolerable side effects. Second, we recommend that each patient undergo a standardized, stepwise evaluation to assess adherence to dietary and lifestyle modifications and antihypertensive medications to identify and reduce barriers and discontinue use of substances that may exacerbate hypertension. Patients in whom there is high clinical suspicion should be evaluated for potential secondary causes of hypertension. Evidence-based management of resistant hypertension is discussed with special considerations of the differences in approach to patients with and without CKD, including the specific roles of diuretics and mineralocorticoid receptor antagonists and the current place of emerging therapies, such as renal denervation and baroreceptor stimulation. We endorse use of such a systematic approach to improve recognition and care for this vulnerable patient group that is at high risk for future kidney and cardiovascular events.

A Randomized Crossover Trial of Dietary Sodium Restriction in Stage 3-4 CKD

BACKGROUND AND OBJECTIVES

Patients with chronic kidney disease (CKD) are often volume expanded and hypertensive. Few controlled studies have assessed the effects of a sodium-restricted diet (SRD) in CKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We conducted a randomized crossover trial to evaluate the effect of SRD (target <2 g sodium per day) versus usual diet on hydration status (by bioelectrical impedance spectroscopy) and blood pressure (BP) between May of 2009 and May of 2013. A total of 58 adults with stage 3-4 CKD were enrolled from two academic sites: University of Michigan (n=37) and University of North Carolina at Chapel Hill (n=21); 60% were men, 43% were diabetic, 93% were hypertensive, and mean age was 61 years. Participants followed SRD or usual diet for 4 weeks, followed by a 2-week washout period and a 4-week crossover phase. During the SRD, dieticians provided counseling every 2 weeks, using motivational interviewing techniques.

RESULTS

Whole-body extracellular volume and calf intracellular volume decreased by 1.02 L (95% confidence interval [95% CI], -1.48 to -0.56; P<0.001) and -0.06 L (95% CI, -0.12 to -0.01; P=0.02), respectively, implying decreased fluid content on the SRD compared with usual diet. Significant reductions in urinary sodium (-57.3 mEq/24 h; 95% CI, -81.8 to -32.9), weight (-2.3 kg; 95% CI, -3.2 to -1.5), and 24-hour systolic BP (-10.8 mmHg; 95% CI, -17.0 to -4.6) were also observed (all P<0.01). Albumin-to-creatinine ratio did not change significantly and mean serum creatinine increased slightly (0.1 mg/dl; 95% CI, -0.01 to 0.2; P=0.06). No period or carryover effects were observed. Results were similar when analyzed from phase 1 only before crossover, although P values were modestly larger because of the loss of power.

CONCLUSIONS

In this randomized crossover trial, implementation of SRD in patients with CKD stage 3-4 resulted in clinically and statistically significant improvement in BP and hydration status. This simple dietary intervention merits a larger trial in CKD to evaluate effects on major clinical outcomes.

Diuretics in the treatment of hypertension

Diuretics have long been used for the treatment of hypertension. Thiazide diuretics are the most commonly prescribed diuretics for hypertension, but other classes of diuretics may be useful in alternative circumstances. Although diuretics are no longer considered the preferred agent for treatment of hypertension in adults and children, they remain acceptable first-line options. Diuretics effectively decrease blood pressure in hypertensive patients, and in adults with hypertension reduce the risk of adverse cardiovascular outcomes. Because of varied pharmacokinetic and pharmacodynamic differences, chlorthalidone may be the preferred thiazide diuretic in the treatment of primary hypertension. Other types of diuretics (e.g., loop, potassium sparing) may be useful for the treatment of hypertension related to chronic kidney disease (CKD) and other varied conditions. Common side effects of thiazides are mostly dose-related and involve electrolyte and metabolic abnormalities.

Chronic Kidney Disease, Fluid Overload and Diuretics: A Complicated Triangle

BACKGROUND

Despite promising role of diuretics to manage fluid overload among chronic kidney disease (CKD) patients, their use is associated with adverse renal outcomes. Current study aimed to determine the extent of renal deterioration with diuretic therapy.

METHODS

A total 312 non-dialysis dependent CKD (NDD-CKD) patients were prospectively followed-up for one year. Fluid overload was assessed via bioimpedance spectroscopy. Estimated GFR (eGFR) was calculated from serum creatinine values by using Chronic Kidney Disease- Epidemiology Collaboration (CKD-EPI) equation.

RESULTS

Out of 312 patients, 64 (20.5%) were hypovolemic while euvolemia and hypervolemia were observed in 113 (36.1%) and 135 (43.4%) patients. Overall 144 patients were using diuretics among which 98 (72.6%) were hypervolemic, 35 (30.9%) euvolemic and 11 (17.2%) were hypovolemic. The mean decline in estimated GFR of entire cohort was -2.5 ± 1.4 ml/min/1.73m2 at the end of follow up. The use of diuretics was significantly associated with decline in eGFR. A total of 36 (11.5%) patients initiated renal replacement therapy (RRT) and need of RRT was more profound among diuretic users.

CONCLUSIONS

The use of diuretics was associated with adverse renal outcomes indicated by decline in eGFR and increasing risk of RRT initiation in our cohort of NDD-CKD patients. Therefore, it is cautiously suggested to carefully prescribe diuretics by keeping in view benefit versus harm for each patient.

Hypertension Management in Transition: From CKD to ESRD

Hypertension is present in ∼90% of patients in late-stage CKD. There are scarce data focusing on the transition period between CKD Stages 4 and 5 (end-stage kidney disease) as it relates to hypertension evaluation and management. Here, we propose that a combination of the principles used in the management of patients with CKD Stages 4 and 5 be applied to patients in this transition. These include the use of out-of-office blood pressure (BP) monitoring (eg, home BP), avoidance of excessively tight BP goals, emphasis of sodium restriction, preferential use of blockers of the renin-angiotensin system and diuretics, and consideration of the use of beta blockers.

Sodium and Volume Disorders in Advanced Chronic Kidney Disease

The kidney has a remarkable ability to modulate sodium and water excretion to maintain homeostasis despite a widely varying dietary intake. However, as glomerular filtration rate falls to less than 30 mL/min, this ability can be compromised leading to an increased risk for disorders of serum sodium and extracellular volume. In all cases, these disorders are associated with an increased rate of morbidity and mortality. Management strategies to both prevent and treat these conditions are available but requiring special attention to the unique circumstance of advanced CKD to maximize therapeutic response and prevent complications.

Safety and efficacy of long-term tolvaptan therapy for decompensated liver cirrhosis

AIM

Recently, the short-term efficacy of the vasopressin V2 receptor antagonist tolvaptan for the treatment of ascites in cirrhosis was reported. However, the long-term effects remain unknown. Here, we report the clinical features of decompensated cirrhosis treated using long-term tolvaptan therapy, and evaluate its safety and efficacy.

METHODS

Fifty-five cirrhotic patients hospitalized due to ascites, despite receiving appropriate diuretic treatment, were treated with tolvaptan. We excluded 35 patients due to liver transplant (20.0%), death (28.6%), poor general status (14.3%), improved ascites (5.7%) or other reasons (31.4%). In 20 cases treated with tolvaptan for 6 months, total body water (TBW) and extracellular fluids (ECW) were measured using bioelectric impedance analysis (BIA) with an InBody720.

RESULTS

The median age of the 20 patients was 64 years (range, 48-90), and 60% were male. The etiology of cirrhosis included hepatitis C (45%), alcohol-induced (20%) and other (35%). The percentage of patients with Child-Pugh class A, B and C was 0%, 40% and 60%, respectively. Biochemical findings revealed that serum creatinine levels and estimated glomerular filtration rate were not affected during 6 months of treatment with tolvaptan, and there was no renal disturbance. The median serum sodium levels were increased from 138 to 139 mEq/L, but serious adverse events related to renal and liver function were not observed. Data also revealed that long-term treatment reduced the BIA-estimated ECW/TBW ratio.

CONCLUSION

Long-term tolvaptan treatment was a safe and effective treatment for decompensated cirrhosis.

Dual Impact of Tolvaptan on Intracellular and Extracellular Water in Chronic Kidney Disease Patients with Fluid Retention

Objective Tolvaptan, an oral selective V2-receptor antagonist, is a water diuretic that ameliorates fluid retention with a lower risk of a worsening renal function than conventional loop diuretics. Although loop diuretics predominantly decrease extracellular water (ECW) compared with intracellular water (ICW), the effect of tolvaptan on fluid distribution remains unclear. We therefore examined how tolvaptan changes ICW and ECW in accordance with the renal function. Methods Six advanced chronic kidney disease patients (stage 4 or 5) with fluid retention were enrolled in this study. Tolvaptan (7.5 mg/day) added to conventional diuretic treatment was administered to remove fluid retention. The fluid volume was measured using a bioimpedance analysis device before (day 0) and after (day 5 or 6) tolvaptan treatment. Results Body weight decreased by 2.6%±1.3% (64.4±6.5 vs. 62.8±6.3 kg, p=0.06), and urine volume increased by 54.8%±23.9% (1,215±169 vs. 1,709±137 mL/day, p=0.03) between before and after tolvaptan treatment. Tolvaptan significantly decreased ICW (6.5%±1.5%, p=0.01) and ECW (7.5%±1.4%, p=0.02), which had similar reduction rates (p=0.32). The estimated glomerular filtration rate remained unchanged during the treatment (14.6±2.8 vs. 14.9±2.7 mL/min/1.73² m, p=0.35). Conclusion Tolvaptan ameliorates body fluid retention, and induces an equivalent reduction rate of ICW and ECW without a worsening renal function. Tolvaptan is a novel water diuretic that has a different effect on fluid distribution compared with conventional loop diuretics.

Uric acid, indoxyl sulfate, and methylguanidine activate bulbospinal neurons in the RVLM via their specific transporters and by producing oxidative stress

Patients with chronic renal failure often have hypertension, but the cause of hypertension, other than an excess of body fluid, is not well known. We hypothesized that the bulbospinal neurons in the rostral ventrolateral medulla (RVLM) are stimulated by uremic toxins in patients with chronic renal failure. To investigate whether RVLM neurons are sensitive to uremic toxins, such as uric acid, indoxyl sulfate, or methylguanidine, we examined changes in the membrane potentials (MPs) of bulbospinal RVLM neurons of Wister rats using the whole-cell patch-clamp technique during superfusion with these toxins. A brainstem-spinal cord preparation that preserved the sympathetic nervous system was used for the experiments. During uric acid, indoxyl sulfate, or methylguanidine superfusion, almost all the RVLM neurons were depolarized. To examine the transporters for these toxins on RVLM neurons, histological examinations were performed. The uric acid-, indoxyl sulfate-, and methylguanidine-depolarized RVLM neurons showed the presence of urate transporter 1 (URAT 1), organic anion transporter (OAT)1 or OAT3, and organic cation transporter (OCT)3, respectively. Furthermore, the toxin-induced activities of the RVLM neurons were suppressed by the addition of an anti-oxidation drug (VAS2870, an NAD(P)H oxidase inhibitor), and a histological examination revealed the presence of NAD(P)H oxidase (nox)2 and nox4 in these RVLM neurons. The present results show that uric acid, indoxyl sulfate, and methylguanidine directly stimulate bulbospinal RVLM neurons via specific transporters on these neurons and by producing oxidative stress. These uremic toxins may cause hypertension by activating RVLM neurons.

Defining, Treating, and Understanding Chronic Kidney Disease--A Complex Disorder

Chronic kidney disease (CKD) is prevalent in more than 20 million people in the United States. The majority of care provided to patients with this disease comes from primary care physicians, although it is often poorly understood. After an extensive literature review, it is clear that it can be difficult to classify and there are many barriers to care. Risk factors for both incident CKD and disease progression include hypertension, poor glycemic control, sociodemographic factors, acute kidney injury, metabolic acidosis, and possibly hyperuricemia and dietary factors. Treatment of patients with CKD should focus on mitigating risk factors, as well as common comorbidities such as cardiovascular disease, anemia, and bone mineral disease. Novel therapies such as pirfenidone, pentoxifylline, and endothelin-1 antagonists are being investigated with promising results.

Determination of extracellular fluid volume in healthy and azotemic cats

BACKGROUND

Methods for determining extracellular fluid volume (ECFV) are important clinically for cats. Bromide dilution has been studied in cats to estimate ECFV. Markers of GFR also distribute in ECFV and can be used for its measurement.

HYPOTHESIS/OBJECTIVES

The primary objective was to develop a method of determining ECFV from iohexol clearance in cats and evaluate agreement with that determined using bromide dilution. Additional objectives were to compare ECFV between azotemic and nonazotemic cats and evaluate appropriate methods of standardizing ECFV.

ANIMALS

Client-owned cats with varying renal function.

METHODS

Validation of ECFV determined from slope-intercept iohexol clearance was performed in 18 healthy nonazotemic cats. ECFV was then determined using the validated method and bromide dilution and agreement assessed. Appropriateness of standardization to body weight (BW) and body surface area (BSA) was evaluated.

RESULTS

Extracellular fluid volume determined from slope-intercept iohexol clearance and bromide dilution was 0.84 ± 0.32 L and 0.85 ± 0.19 L (mean ± SD), respectively. There were wide limits of agreement between the methods (-0.58 to 0.54 L) and therefore, agreement was considered to be poor. ECFV did not differ significantly between azotemic and nonazotemic cats (P = .177). BSA was found to be the best method for standardizing ECFV measurement in cats.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study developed a method for determining ECFV from slope-intercept iohexol clearance which provides simultaneous assessment of renal function and an estimate of ECFV. ECFV does not differ between azotemic and nonazotemic cats, which suggests fluid volume loss or overload is not an important clinical feature in cats with mild chronic kidney disease.

Chlorthalidone for poorly controlled hypertension in chronic kidney disease: an interventional pilot study

To test the hypothesis that thiazide-type diuretics effectively lower blood pressure (BP) in moderate to advanced chronic kidney disease (CKD; estimated GFR 20-45 ml/min/ 1.73 m(2)), after confirming poorly controlled hypertension with 24-hour ambulatory BP monitoring, chlorthalidone was added to existing medications in a dose of 25 mg/day, and the dose doubled every 4 weeks if the BP remained elevated. The average age of the 14 subjects was 67.5 years, a median of 4 antihypertensive drugs were used and estimated GFR was 26.8 ± 8.8 ml/min/1.73 m(2). Twelve subjects completed the 12-week treatment phase, and the 24-hour BP, which was 143.1/75.1 mm Hg at baseline, was reduced by 10.5/ 3.1 mm Hg (p = 0.01/p = 0.17). Home BP prior to initiating chlorthalidone was 152.4/82.6 mm Hg and fell at 4, 8, and 12 weeks by 10.2/4.8, 13.4/6.0, and 9.4/3.7 mm Hg (all p < 0.05). Maximal reduction in body weight and total body volume (measured by air displacement plethysmography) was seen at 8 weeks, concurrent with the maximal elevation in serum creatinine concentration and plasma renin activity. Albuminuria was significantly reduced by 40-45%. Adverse events were seen following chlorthalidone therapy in 7 subjects who experienced 18 events as follows: hypokalemia (n = 4), hyperuricemia (4), hyponatremia (3), transient creatinine changes (3), dizziness (2), hyperglycemia (1), and constipation (1). One subject had ischemic stroke during the study. In conclusion, among people with moderate to advanced CKD with poorly controlled hypertension, chlorthalidone may significantly reduce BP via volume contraction; a randomized trial is needed to define the risks and benefits. Adverse effects may occur within a few weeks and should be carefully monitored.

Is fluid overload more important than diabetes in renal progression in late chronic kidney disease?

Fluid overload is one of the major presentations in patients with late stage chronic kidney disease (CKD). Diabetes is the leading cause of renal failure, and progression of diabetic nephropathy has been associated with changes in extracellular fluid volume. The aim of the study was to assess the association of fluid overload and diabetes in commencing dialysis and rapid renal function decline (the slope of estimated glomerular filtration rate (eGFR) less than -3 ml/min per 1.73 m(2)/y) in 472 patients with stages 4-5 CKD. Fluid status was determined by bioimpedance spectroscopy method, Body Composition Monitor. The study population was further classified into four groups according to the median of relative hydration status (△HS =fluid overload/extracellular water) and the presence or absence of diabetes. The median level of relative hydration status was 7%. Among all patients, 207(43.9 %) were diabetic. 71 (15.0%) subjects had commencing dialysis, and 187 (39.6%) subjects presented rapid renal function decline during a median 17.3-month follow-up. Patients with fluid overload had a significantly increased risk for commencing dialysis and renal function decline independent of the presence or absence of diabetes. No significantly increased risk for renal progression was found between diabetes and non-diabetes in late CKD without fluid overload. In conclusion, fluid overload has a higher predictive value of an elevated risk for renal progression than diabetes in late CKD.

NGAL and NT-proBNP levels in diabetic patients with macroproteinuria

BACKGROUND

In patients with heart failure plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) levels are correlated to urine neutrophil gelatinase-associated lipocalin (NGAL) levels. We prospectively evaluated the relationship among glomerular filtration rate (eGFR), urine albumin-to-creatinine ratio (ACR), urine and serum NGAL and NT-proBNP levels in 20 type II diabetic patients with macroalbuminuria at 4-month intervals.

RESULTS

Compared with 20 age, gender-matched healthy controls, diabetic patients had higher urine and serum NGAL, serum NT-proBNP and lower eGFR. The eGFR of the patients at the baseline, the 4th and the 8th month were 29.6 ± 12.0, 27.8 ± 13.7 and 22.9 ± 10.4 mL/min/1.73 m(2), respectively. No significant change in urine NGAL levels was detected (p > 0.05), whereas there were significant increases in NT-proBNP, serum NGAL and urine ACR and significant decrease in eGFR as the study progressed (p < 0.05). Both the baseline and the 4th month urine ACR were positively correlated to NT-proBNP levels measured at the same periods (r: 0.451; p: 0.046; r: 0.489; p: 0.029 respectively). In all measurements, urine ACR was negatively correlated to serum albumin levels measured at the same periods (r: -0.792; p: 0.000; r: -0.716; p: 0.000; r: -0.531; p: 0.016 respectively). None of eGFR measurements was correlated with NT-proBNP (p > 0.05). Neither serum NGAL nor urinary NGAL levels are associated with NT-proBNP (p > 0.05).

CONCLUSION

Our findings show an association between NT-proBNP and proteinuria in type II diabetic patients with macroalbuminuria but not with serum and urine NGAL.

Pharmacologic treatment of hypertension in patients with chronic kidney disease

Hypertension remains an important cause of morbidity and mortality in patients with chronic kidney disease. It both contributes to and is a consequence of chronic renal dysfunction. There is a high prevalence of hypertension in chronic kidney disease, and rates of control remain sub-optimal. Numerous studies have highlighted the benefit of treating hypertension in reducing the overall mortality as well as progression of renal disease in this population. Non-pharmacologic treatment strategies remain the primary intervention in all patients but are insufficient on their own to control hypertension in most cases. Pharmacologic treatment recommendations, however, vary depending on the specific etiology of disease as well as patient characteristics. Though most classes of anti-hypertensive drugs can be used to lower blood pressure in chronic kidney disease, therapy needs to be selected based on the presence of specific co-morbidities as well as the etiology of the kidney disease. Most patients will require multi-drug therapy for achieving target blood pressure goals. This review discusses the pharmacologic options in management of hypertension in various forms of chronic kidney disease.

Chronic kidney disease, diabetes mellitus and cardiovascular disease: risks and commonalities

The prevalence of chronic kidney disease (CKD) and diabetes mellitus (DM) is increasing worldwide. CKD and diabetes are important risk factors for cardiovascular disease and all three conditions are key components of the multiple morbidities increasingly evident as population age in the developed world. Shared risk factors, both traditional and nontraditional, contribute to these associations, and are important targets for public health and both primary and secondary care. Prevention and early detection in combination with a holistic approach to vascular care will be key to improving outcomes and reducing costs. Routine reporting of estimated glomerular filtration rate to aid early identification, risk stratification through quantitative proteinuria testing, appropriate use of renin-angiotensin system antagonists and optimal blood pressure control are important strategies to improve the care of people with or at risk of CKD.

Subclinical cardiac abnormalities and kidney function decline: the multi-ethnic study of atherosclerosis

BACKGROUND AND OBJECTIVES

Clinical heart failure (HF) is associated with CKD and faster rates of kidney function decline. Whether subclinical abnormalities of cardiac structure are associated with faster kidney function decline is not known. The association between cardiac concentricity and kidney function decline was evaluated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This is a longitudinal study of 3866 individuals from the Multi-Ethnic Study of Atherosclerosis (2000-2007) who were free of clinical cardiovascular disease, with an estimated GFR (eGFR) ≥60 ml/min per 1.73 m(2) at baseline and 5 years of follow-up. Concentricity, a measurement of abnormal cardiac size, was assessed by magnetic resonance imaging and evaluated as a continuous measurement and in quartiles. GFR was estimated by creatinine (eGFRcr) and cystatin C (eGFRcys). The association of concentricity with annual eGFR decline, incident CKD, and rapid kidney function decline (>5% per year) was investigated using linear mixed models as well as Poisson and logistic regression, respectively. Analyses adjusted for demographics, BP, diabetes, and inflammatory markers.

RESULTS

Median decline was -0.8 (interquartile range, -3.1, -0.5) by eGFRcr. Compared with the lowest quartile of concentricity, persons in the highest quartile had an additional 21% (9%-32%) decline in mean eGFRcr in fully adjusted models. Concentricity was also associated with incident CKD and with rapid kidney function decline after adjustment.

CONCLUSIONS

Subclinical abnormalities in cardiac structure are associated with longitudinal kidney function decline independent of diabetes and hypertension. Future studies should examine mechanisms to explain these associations.

Extracellular fluid volume and glomerular filtration rate in 1878 healthy potential renal transplant donors: effects of age, gender, obesity and scaling

Aim. The aim of this study was to investigate the influence of age, gender, obesity and scaling on glomerular filtration rate (GFR) and extracellular fluid volume (ECV) in healthy subjects.

METHODS

This is a retrospective multi-centre study of 1878 healthy prospective kidney transplant donors (819 men) from 15 centres. Age and body mass index (BMI) were not significantly different between men and women. Slope-intercept GFR was measured (using Cr-51-EDTA in 14 centres; Tc-99m-DTPA in one) and scaled to body surface area (BSA) and lean body mass (LBM), both estimated from height and weight. GFR was also expressed as the slope rate constant, with one-compartment correction (GFR/ECV). ECV was measured as the ratio, GFR to GFR/ECV.

RESULTS

ECV was age independent but GFR declined with age, at a significantly faster rate in women than men. GFR/BSA was higher in men but GFR/ECV and GFR/LBM were higher in women. Young women (<30 years) had higher GFR than young men but the reverse was recorded in the elderly (>65 years). There was no difference in GFR between obese (BMI>30 kg/m2) and non-obese men. Obese women, however, had lower GFR than non-obese women and negative correlations were observed between GFR and both BMI and %fat. The decline in GFR with age was no faster in obese versus non-obese subjects. ECV/BSA was higher in men but ECV/LBM was higher in women. ECV/weight was almost gender independent, suggesting that fat-free mass in women contains more extracellular water. BSA is therefore a misleading scaling variable.

CONCLUSION

There are several significant differences in GFR and ECV between healthy men and women.