Cross-sectional relations of serum aldosterone and urine sodium excretion to urinary albumin excretion in a community-based sample

Proteinuria Modifies the Relationship Between Urinary Sodium Excretion and Adverse Kidney Outcomes: Findings From KNOW-CKD

Introduction

High sodium intake is associated with increased proteinuria. Herein, we investigated whether proteinuria could modify the association between urinary sodium excretion and adverse kidney outcomes in patients with chronic kidney disease (CKD).

Methods

In this prospective observational cohort study, we included 967 participants with CKD stages G1 to G5 between 2011 and 2016, who measured 24-hour urinary sodium and protein excretion at baseline. The main predictors were urinary sodium and protein excretion levels. The primary outcome was CKD progression, which was defined as a ≥50% decline in the estimated glomerular filtration rate (eGFR) or the onset of kidney replacement therapy.

Results

During a median follow-up period of 4.1 years, the primary outcome events occurred in 287 participants (29.7%). There was a significant interaction between proteinuria and sodium excretion for the primary outcome (P = 0.006). In patients with proteinuria of <0.5 g/d, sodium excretion was not associated with the primary outcome. However, in patients with proteinuria of ≥0.5 g/d, a 1.0 g/d increase in sodium excretion was associated with a 29% higher risk of adverse kidney outcomes. Moreover, in patients with proteinuria of ≥0.5 g/d, the hazard ratios (HRs) (95% confidence intervals[CIs]) for sodium excretion of <3.4 and ≥3.4 g/d were 2.32 (1.50-3.58) and 5.71 (3.58-9.11), respectively, compared with HRs for patients with proteinuria of <0.5 g/d and sodium excretion of <3.4 g/d. In sensitivity analysis with 2 averaged values of sodium and protein excretion at baseline and third year, the results were similar.

Conclusion

Higher urinary sodium excretion was more strongly associated with an increased risk of adverse kidney outcomes in patients with higher proteinuria levels.

Aldosterone in chronic kidney disease and renal outcomes

AIMS

Randomized controlled trials have demonstrated the efficacy of mineralocorticoid receptor (MR) antagonism in delaying chronic kidney disease (CKD) progression in diabetes; however, they have not investigated the role of aldosterone or whether these beneficial effects could be achieved in individuals without diabetes.

METHODS AND RESULTS

The association between serum aldosterone concentrations and kidney disease progression was investigated among 3680 participants in the Chronic Renal Insufficiency Cohort. The primary outcome was CKD progression [defined as the composite of 50% decline in estimated glomerular filtration rate (eGFR) or end-stage kidney disease, whichever occurred first]. The associations between serum aldosterone and kidney disease outcomes were assessed using Cox proportional hazard models. At baseline, higher aldosterone concentrations were associated with a lower eGFR, lower serum potassium, greater urinary potassium, and protein excretion. Over a median follow-up of 9.6 years, 1412 participants developed CKD progression. In adjusted models, each doubling of serum aldosterone was associated with a 11% increased risk of CKD progression [hazard ratio (HR) 1.11, 95% confidence interval (CI) 1.04-1.18]. Individuals with the highest quartile of serum aldosterone had a 45% increased risk of CKD progression (HR 1.45, 95% CI 1.22-1.73) compared with the lowest quartile. The risk for CKD progression was similar regardless of whether patients had concomitant diabetes (P-interaction = 0.10).

CONCLUSION

Higher serum aldosterone levels among individuals with CKD are independently associated with an increased risk for kidney disease progression, irrespective of concomitant diabetes. These findings provide mechanistic support for MR antagonists in delaying CKD progression and suggest that they may also have a role in those without diabetes.

Clarifying Optimal Sodium InTake In Cardiovasular and Kidney (COSTICK) Diseases: a study protocol for two randomised controlled trials

Background: While low sodium intake (<2.3g/day) is recommended for all, there is uncertainty about feasibility and net cardiovascular effects. In COSTICK, we evaluated the effects of a dietary counselling intervention (reduced sodium intake) on intermediate cardiorenal outcomes in patients with (STICK) and without (COSIP) mild/moderate kidney disease. Methods: This is a protocol for two phase IIb randomised, two-group, parallel, open-label, controlled, single centre trials. Participants were aged >40 years with stable blood pressure, unchanged anti-hypertensive medications, willing to modify diet and provided written informed consent. Participants were excluded for abnormal sodium handling, heart failure, high dose diuretics, immunosuppression, pregnancy/lactation, postural hypotension, cognitive impairment, high or low body mass index (BMI) or inclusion in another trial. STICK participants had estimated glomerular filtration rate (eGFR) 30-60ml/min/1.73m2 and were excluded for acute kidney Injury, rapidly declining eGFR; known glomerular disease or current use of non-steroidal anti-inflammatory drugs. For COSIP, participants were excluded for known kidney or cardiovascular disease. Participants were randomized to usual care only (healthy eating) or an additional sodium lowering intervention (target <100mmol/day) through specific counseling (sodium use in foods, fresh over processed foods, sodium content of foods and eating outside of home). In STICK the primary outcome is change in 24-hour urinary creatinine clearance. In COSIP, the primary outcome is change in five biomarkers (renin, aldosterone, high sensitivity troponin T, pro-B-type natriuretic peptide and C-reactive protein). Our primary report (COSTICK), reports six biomarker outcome measures in the entire population at 2 years follow-up. Discussion: These Phase II trials will explore uncertainty about low sodium intake and cardiovascular and kidney biomarkers, and help determine the feasibility of low sodium intake. Trial results will also provide preliminary information to guide a future definitive clinical trial, if indicated. Trial registration: STICK: ClinicalTrials.gov NCT02738736 (04/04/2016); COSIP: ClinicalTrials.gov NCT02458248 (15/05/2016)

Cerebro-Cardiovascular Risk, Target Organ Damage, and Treatment Outcomes in Primary Aldosteronism

Primary aldosteronism (PA) is the most common type of endocrine hypertension, and numerous experimental and clinical evidence have verified that prolonged exposure to excess aldosterone is responsible for an increased risk of cerebro-cardiovascular events and target organ damage (TOD) in patients with PA. Therefore, focusing on restoring the toxic effects of excess aldosterone on the target organs is very important to reduce cerebro-cardiovascular events. Current evidence convincingly demonstrates that both surgical and medical treatment strategies would benefit cerebro-cardiovascular outcomes and mortality in the long term. Understanding cerebro-cardiovascular risk in PA would help clinical doctors to achieve both early diagnosis and treatment. Therefore, in this review, we will summarize the cerebro-cardiovascular risk in PA, focusing on the TOD of aldosterone, including brain, heart, vascular system, renal, adipose tissues, diabetes, and obstructive sleep apnea (OSA). Furthermore, the various treatment outcomes of adrenalectomy and medical treatment for patients with PA will also be discussed. We hope this knowledge will help improve cerebro-cardiovascular prognosis and reduce the incidence and mortality of cerebro-cardiovascular events in patients with PA.

Association between the urinary sodium-to-potassium ratio and renal outcomes in patients with chronic kidney disease: a prospective cohort study

A higher urinary sodium-to-potassium (UNa/K) ratio has been reported to be associated with high blood pressure and subsequent cardiovascular events. However, the association between the UNa/K ratio and renal outcomes remains uncertain. We prospectively investigated the association between the UNa/K ratio and renal outcomes in patients with chronic kidney disease (CKD). We enrolled 716 patients with CKD, and 24-h urinary sodium and potassium excretion were measured. Patients were divided into UNa/K ratio tertiles (T1-T3). Endpoints were defined as a composite of doubling of serum creatinine (SCr), end-stage kidney disease (ESKD), or death and a composite of doubling of SCr or ESKD (added as an alternative outcome). We investigated the association between the UNa/K ratio and renal outcomes using a Cox proportional hazards model. During a median follow-up of 2.3 years, doubling of SCr, ESKD, or death and doubling of SCr or ESKD occurred in 332 and 293 patients, respectively. After adjustment for covariates including potentially confounding variables such as plasma renin activity, plasma aldosterone concentration, and B-type natriuretic peptide, the hazard ratios (HRs) (95% confidence intervals [CIs]) for the composite of doubling of SCr, ESKD, or death for T2 and T3 were 1.44 (1.06-1.96) and 1.59 (1.14-2.21), respectively, compared with T1. Additionally, compared with T1, the highest tertile (T3) of the UNa/K ratio was associated with a composite of doubling of SCr or ESKD (HR 1.55, 95% CI 1.09-2.20). A higher UNa/K ratio was independently associated with poor renal outcomes in patients with CKD.

Clarifying Optimal Sodium InTake In Cardiovasular and Kidney (COSTICK) Diseases: a study protocol for two randomised controlled trials

Background: While low sodium intake (<2.3g/day) is recommended for all, there is uncertainty about feasibility and net cardiovascular effects. In COSTICK, we evaluated the effects of a dietary counselling intervention (reduced sodium intake) on intermediate cardiorenal outcomes in patients with (STICK) and without (COSIP) mild/moderate kidney disease. Methods: This is a protocol for two phase IIb randomised, two-group, parallel, open-label, controlled, single centre trials. Participants were aged >40 years with stable blood pressure, unchanged anti-hypertensive medications, willing to modify diet and provided written informed consent. Participants were excluded for abnormal sodium handling, heart failure, high dose diuretics, immunosuppression, pregnancy/lactation, postural hypotension, cognitive impairment, high or low body mass index (BMI) or inclusion in another trial. STICK participants had estimated glomerular filtration rate (eGFR) 30-60ml/min/1.73m2 and were excluded for acute kidney Injury, rapidly declining eGFR; known glomerular disease or current use of non-steroidal anti-inflammatory drugs. For COSIP, participants were excluded for known kidney or cardiovascular disease. Participants were randomized to usual care only (healthy eating) or an additional sodium lowering intervention (target <100mmol/day) through specific counseling (sodium use in foods, fresh over processed foods, sodium content of foods and eating outside of home). In STICK the primary outcome is change in 24-hour urinary creatinine clearance. In COSIP, the primary outcome is change in five biomarkers (renin, aldosterone, high sensitivity troponin T, pro-B-type natriuretic peptide and C-reactive protein). Our primary report (COSTICK), reports six biomarker outcome measures in the entire population at 2 years follow-up. Discussion: These Phase II trials will explore uncertainty about low sodium intake and cardiovascular and kidney biomarkers, and help determine the feasibility of low sodium intake. Trial results will also provide preliminary information to guide a future definitive clinical trial, if indicated. Trial registration: STICK: ClinicalTrials.gov NCT02738736 (04/04/2016); COSIP: ClinicalTrials.gov NCT02458248 (15/05/2016)

Association between urinary salt excretion and albuminuria in Japanese patients with chronic kidney disease: the Fukuoka kidney disease registry study

BACKGROUND

Several large population-based studies have demonstrated that urinary salt excretion (USALT) is associated with albuminuria. However, this relationship has not been assessed in a large cohort study of patients with chronic kidney disease (CKD). Thus, the present study aimed to elucidate whether USALT was independently associated with albuminuria in a large cohort of patients with CKD.

METHODS

This cross-sectional study was conducted in 4075 patients with CKD not on dialysis. USALT (g/day) was estimated from spot urine. Patients were divided into quartiles (Q1-Q4) according to estimated USALT. Multivariable regression models were used to determine whether USALT was independently related to urinary albumin-to-creatinine ratio (UACR) or the presence of macroalbuminuria.

RESULTS

In multivariable linear regression analyses, 1-g/day increment in USALT was significantly associated with log UACR [coefficient 0.098, 95% confidence interval (CI) 0.075-0.121]. In addition, compared with the first USALT quartile, the third and fourth quartiles exhibited significant associations with log UACR (Q3: coefficient 0.305, 95% CI 0.154-0.456; Q4: coefficient 0.601, 95% CI 0.447-0.756). Furthermore, multivariable logistic regression analyses showed that USALT (1-g/day increment) was significantly associated with the presence of macroalbuminuria [odds ratio (OR) 1.11, 95% CI 1.07-1.14]; the third and fourth USALT quartiles exhibited significantly greater risks of macroalbuminuria, compared with the first quartile (Q3: OR 1.33, 95% CI 1.09-1.62; Q4: OR 1.89, 95% CI 1.54-2.32).

CONCLUSIONS

This significant association of USALT with UACR and macroalbuminuria suggests that higher USALT may cause increased albuminuria, thereby contributing to kidney disease progression.

Long-term phase 3 study of esaxerenone as mono or combination therapy with other antihypertensive drugs in patients with essential hypertension

This study investigated the long-term antihypertensive effects of esaxerenone, a novel nonsteroidal mineralocorticoid receptor blocker, alone or in combination with a calcium channel blocker (CCB) or a renin-angiotensin system (RAS) inhibitor, in Japanese patients with essential hypertension. Patients were treated with esaxerenone starting at 2.5 mg/day increasing to 5 mg/day if required to achieve blood pressure (BP) targets as a monotherapy or with a CCB or RAS inhibitor. After the first 12 weeks of treatment, an additional antihypertensive agent could be added if required to achieve the target BP; the total treatment period was 28 or 52 weeks. The primary endpoint was a change from baseline in sitting BP. Of the 368 enrolled patients, 245 received monotherapy, and 59 and 64, respectively, took a CCB or RAS inhibitor concurrently. Mean changes from baseline in sitting systolic/diastolic BP (95% confidence intervals) at weeks 12, 28 and 52 were -16.1 (-17.3, -14.9)/-7.7 (-8.4, -6.9), -18.9 (-20.2, -17.7)/-9.9 (-10.7, -9.2), and -23.1 (-25.0, -21.1)/-12.5 (-13.6, -11.3) mmHg, respectively (all P < 0.0001 vs baseline). Similar BP reductions at these weeks were observed between all patient subgroups stratified by age, and the observed decreases in 24-h ambulatory BP were consistent with the efficacy observed in sitting BP. Esaxerenone was also well-tolerated with a rate of hyperkalemia at 5.4% (serum potassium ≥5.5 mEq/L), indicating a good safety profile for treatment over the long-term or in combination with a CCB or RAS inhibitor. In conclusion, esaxerenone may be a promising treatment option for patients with hypertension.

Salt-induced effects on microvascular function: A critical factor in hypertension mediated organ damage

Salt has been linked very closely to the occurrence and complications of arterial hypertension. A large percentage of patients with essential hypertension are salt-sensitive; that is, their blood pressure increases with increased salt intake and decreases with its reduction. For this reason, emphasis is placed on reducing salt intake to better regulate blood pressure. In day-to-day clinical practice this is viewed as mandatory for hypertensive patients who are judged to be salt-sensitive. Previous studies have highlighted the negative effect of high-salt diets on macrovascular function, which also affects blood pressure levels by increasing peripheral resistances. More recent studies provide a better overview of the pathophysiology of microvascular disorders and show that they are largely due to the overconsumption of salt. Microvascular lesions, which have a major impact on the functioning of vital organs, are often not well recognized in clinical practice and are not paid sufficient attention. In general, the damage caused by hypertension to the microvascular network is likely to be overlooked, while reversion of the damage is only rarely considered as a therapeutic target by the treating physician. The purpose of this review is to summarize the impact and the harmful consequences of increased salt consumption in the microvascular network, their significance and pathophysiology, and at the same time to place some emphasis on their treatment and reversion, mainly through diet.

Renal function in relation to sodium intake: a quantitative review of the literature

We undertook a quantitative literature review to search for evidence underpinning current guidelines proposing a reduction of sodium intake to less than 2.4 g/d for the management of chronic kidney disease. We searched PubMed for peer-reviewed articles published from January 1980 through May 2016. Two investigators screened 5072 publications and extracted data from 36, including 11 cross-sectional and 5 longitudinal observational studies and 20 intervention trials. Within-study effect sizes were pooled and standardized to a sodium gradient of 100 mmol/d by using inverse-variance weighted random effects models. Among cross-sectional studies, the pooled odds ratio for albuminuria was 1.23 (95% confidence interval [CI], 0.92-1.64, P = 0.16), and the pooled mean difference in glomerular filtration rate amounted to 8.5 ml/min (CI, -2.3 to 19.2 ml/min; P = 0.12). In the cohort studies, the pooled relative risk of a renal endpoint was 1.08 (CI, 0.92-1.29; P = 0.35). In the intervention trials (median duration, 14 days [range, 4-186 days]), the mean differences in estimated glomerular filtration rate and albuminuria (high vs. low sodium intake) averaged 4.6 ml/min (CI, 3.4-5.8 ml/min; P < 0.0001) and 53% (CI, 21-84; P = 0.001), respectively. Cochran's Q statistic indicated significant heterogeneity among cross-sectional studies for both estimated glomerular filtration rate and albuminuria (P < 0.0001) and among intervention trials for albuminuria (P = 0.04). In conclusion, there is no robust evidence suggesting that long-term reduction of salt intake would prevent chronic kidney disease or delay its progression. However, our current findings, which were mainly obtained in people with slight renal impairment, cannot be extrapolated to patients with moderate or severe chronic kidney disease.

Drug therapy of apparent treatment-resistant hypertension: focus on mineralocorticoid receptor antagonists

Apparent treatment-resistant hypertension (aTRH) is defined as blood pressure (BP) >140/90 mmHg despite three different antihypertensive drugs including a diuretic. aTRH is associated with an increased risk of cardiovascular events, including stroke, chronic renal failure, myocardial infarction, congestive heart failure, aortic aneurysm, atrial fibrillation, and sudden death. Preliminary studies of renal nerve ablation as a therapy to control aTRH were encouraging. However, these results were not confirmed by the Symplicity 3 trial. Therefore, attention has refocused on drug therapy. Secondary forms of hypertension and associated conditions such as obesity, sleep apnea, and primary aldosteronism are common in patients with aTRH. The pivotal role of aldosterone in the pathogenesis of aTRH in many cases is well recognized. For patients with aTRH, the Joint National Committee-8, the European Society of Hypertension, and a recent consensus conference recommend that a diuretic, ACE inhibitor, or angiotensin receptor blocker and calcium channel blocker combination be used to maximally tolerated doses before starting a 'fourth-line' drug such as a mineralocorticoid receptor (MR) antagonist. Although the best fourth-line drug for aTRH has not been extensively investigated, a number of studies summarized here show that an MR antagonist is effective in reducing BP when added to the standard multi-drug regimen.

Higher dietary salt intake is associated with microalbuminuria, but not with retinopathy in individuals with type 1 diabetes: the EURODIAB Prospective Complications Study

AIMS/HYPOTHESIS

High dietary salt intake has been associated with elevated BP and may also have a deleterious effect on microvascular complications. We studied the cross-sectional associations between dietary salt intake (estimated from 24 h urinary sodium excretion) and urinary potassium excretion on the one hand, and the prevalence of microvascular complications on the other, in individuals with type 1 diabetes.

METHODS

We measured sodium and potassium concentrations in two 24 h urine samples in 1,212 individuals with type 1 diabetes (40 ± 10 years old, 51% men) who participated in the EURODIAB Prospective Complications Study. We used multiple logistic regression analyses to investigate associations between dietary salt intake and microvascular complications adjusted for age and sex, and additionally for BMI, smoking, urinary potassium excretion, antihypertensive medication and physical activity, and total energy, protein, alcohol, saturated fat and fibre intake.

RESULTS

After full adjustment, 1 g/day higher dietary salt intake was positively associated with the presence of microalbuminuria (OR 1.06 [95% CI 1.01, 1.10]), but not macroalbuminuria (OR 0.99 [95% CI 0.94, 1.05]), non-proliferative retinopathy (OR 1.00 (95% CI 0.96, 1.04]) or proliferative retinopathy (OR 1.02 (95% CI 0.95, 1.08]). After excluding individuals with cardiovascular disease and/or antihypertensive medication (n = 418), we found a non-significant association with microalbuminuria (OR 1.04 [95% CI 0.99, 1.10]) and macroalbuminuria (OR 1.05 [95% CI 0.96, 1.16]). The association between dietary salt intake and microalbuminuria was stronger in individuals with a BMI above 25 kg/m(2) (OR 1.11 [95% CI 1.04, 1.18]) than in those with BMI below 25 kg/m(2) (OR 1.03 [95% CI 0.97, 1.09]). No significant associations were found between urinary potassium excretion and microvascular complications.

CONCLUSIONS/INTERPRETATION

In individuals with type 1 diabetes, higher dietary salt intake, as determined by 24 h urinary sodium excretion, may be positively associated with microalbuminuria, particularly in overweight individuals.

Association of the estimated 24-h urinary sodium excretion with albuminuria in adult koreans: the 2011 Korea National Health and Nutrition Examination Survey

BACKGROUND

Sodium intake and albuminuria have important roles in blood pressure and renal progression. Although their relationship has been reported, the results have not been consistent and all studies have examined small populations.

OBJECTIVE

This study investigated the role of the estimated 24-h urinary sodium excretion as a marker of sodium intake and albuminuria.

DESIGN

This investigation included 5,187 individuals age 19 years and older from a cross-sectional, nationally representative, stratified survey: The Korea National Health and Nutrition Examination Survey (KNHANES V-2), in 2011. Albuminuria was defined as a urinary albumin/creatinine ratio ≥30 mg/g. The 24-h urinary sodium excretion was estimated from a spot urine.

RESULTS

On classifying our participants into quartiles based on the estimated 24-h urinary sodium excretion, the prevalence of albuminuria increased with the 24-h urinary sodium excretion (5.3, 5.7, 7.5, and 11.8% in the first through fourth quartiles, respectively, p for trend <0.001). Even after adjusting for age, sex, diabetes, obesity, and hypertension, the significance persisted. In a multiple logistic regression analysis, the second and third quartiles of the estimated 24-h urinary sodium excretion were not associated with the presence of albuminuria with the first quartile as a control. However, the fourth quartile was significantly associated with the presence of albuminuria (odds ratio 1.61 [95% confidence interval 1.71-2.21], p = 0.003) after adjusting for age, sex, diabetes, obesity, and hypertension.

CONCLUSIONS

These findings suggest that salt intake is associated with the presence of albuminuria in the general Korean adult population.

Aldosterone blockade in chronic kidney disease

Although blockade of the renin-angiotensin-aldosterone system with angiotensin-converting enzyme inhibitors or angiotensin-receptor blockers has become standard therapy for chronic kidney disease (CKD), renewed interest in the role of aldosterone in mediating the injuries and progressive insults of CKD has highlighted the potential role of treatments targeting the mineralocorticoid receptor (MR). Although salt restriction is an important component of mitigating the profibrotic effects of MR activation, a growing body of literature has shown that MR antagonists, spironolactone and eplerenone, can reduce proteinuria and blood pressure in patients at all stages of CKD. These agents carry a risk of hyperkalemia, but this risk likely can be predicted based on baseline renal function and mitigated using dietary modifications and adjustments of concomitant medications. Data on hard outcomes, such as progression to end-stage renal disease and overall mortality, still are lacking in patients with CKD.

Metabolic syndrome and associated urolithiasis in adults enrolled in a community-based health program

BACKGROUND

Urolithiasis is a common and recurrent disease, whose prevalence rate has recently increased in parallel to obesity pandemic.

OBJECTIVES

To estimate the prevalence of history of urolithiasis in a non-randomized sample of adults assisted by a community-based health program and to analyze its association with metabolic syndrome.

METHODS

Cross-sectional study set in Niteroi, Rio de Janeiro, Brazil, including adults (non-diabetic hypertensives, diabetics or controls). Participants were assessed through a standardized questionnaire and underwent clinical and laboratory evaluation, including blood and urine samples. The diagnosis of metabolic syndrome was based on harmonized criteria.

RESULTS

A total of 740 adults were enrolled (M: F = 0.85; 43±12 years; 30% white, and 70% non-white). Almost half of subjects (42.5%) had metabolic syndrome. The prevalence of urolithiasis in the sample was 10.1%. White skin colour, family history, and metabolic syndrome were independently associated with urolithiasis (P < 0.05). Subjects with the syndrome (excluding cases on diuretics) had more acidic urine (P = 0.014), increased natriuresis (P = 0.01) and higher uricosuria (P = 0.001) compared with non-affected ones. The prevalence of urolithiasis increased in proportion to the number of criteria for metabolic syndrome (P for trend <0.005).

CONCLUSIONS

Metabolic syndrome is a modifiable factor associated with urolithiasis in a way that the frequency of positive history increases proportionally to the number of its diagnostic criteria. These findings reinforce the recent suggested link between urolithiasis and cardiovascular risk factors.

Salt, aldosterone and hypertension

Clinical studies have shown that aldosterone and salt are independently related to hypertension, cardiovascular morbidity and mortality. More recently, studies in humans have demonstrated that, similarly to animals, endogenous aldosterone and dietary salt intake have not only separate, but also combined effects to accelerate target-organ deterioration. The aldosterone-salt interaction has important clinical implications, because combined effects of both can be minimized, if not avoided, by reducing salt intake. This interaction could also be interrupted by blocking the effects of aldosterone, with use of mineralocorticoid receptor antagonists, or by reducing aldosterone effects by adrenalectomy, in patients with aldosterone producing adenoma. Furthermore, aldosterone reduction or blockade may reduce salt appetite.

Effects of a Novel Aldosterone Synthase Inhibitor for Treatment of Primary Hypertension

Background—

LCI699, a novel inhibitor of aldosterone synthase, reduces serum aldosterone, and may have benefit in the treatment of hypertension.

Methods and Results—

We performed the first double-blind, randomized trial with LCI699 in patients with primary hypertension. We randomized 524 patients to LCI699 0.25 mg once daily (n=92), 0.5 mg once daily (n=88), 1.0 mg once daily (n=86), and 0.5 mg twice daily (n=97); eplerenone 50 mg twice daily (n=84); or placebo (n=77) for 8 weeks. Adrenocorticotropic hormone (250 μg IV) stimulation testing was performed in a subset of patients to quantify the selectivity of LCI699 for aldosterone synthase compared with 11-β-hydroxylase. Reductions in clinic diastolic blood pressure were significant for LCI699 1.0 mg (−7.1 mm Hg; P =0.0012) and eplerenone 50 mg twice daily (−7.9 mm Hg; P <0.0001) compared with placebo (−2.6 mm Hg) but not other doses of LCI699. Significant reductions in clinic systolic blood pressure were observed with all doses of LCI699 ( P <0.005 or better) and eplerenone ( P <0.0001). All doses of LCI699 significantly reduced 24-hour ambulatory blood pressure compared with placebo ( P <0.01). Adrenocorticotropic hormone stimulation of cortisol was suppressed in ≈20% of subjects receiving LCI699 at a total daily dose of 1.0 mg. Safety and tolerability were similar among LCI699, placebo, and eplerenone.

Conclusions—

Aldosterone synthase inhibition with LCI699 significantly lowered clinic and ambulatory blood pressure. A minority of subjects developed blunted adrenocorticotropic hormone–stimulated release of cortisol. These results support additional research to evaluate use of aldosterone synthase inhibition in primary hypertension and/or patients characterized by aldosterone excess.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00758524.

Association of dietary sodium and potassium intakes with albuminuria in normal-weight, overweight, and obese participants in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study

BACKGROUND

Among obese adults, sodium intake has been associated with cardiovascular disease. Few data are available on sodium intake and albuminuria, a marker of kidney damage and risk factor for cardiovascular disease.

OBJECTIVE

We examined the relation between dietary sodium and potassium intakes and the ratio of sodium to potassium (Na/K) with albuminuria by BMI in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) Study (n = 30,239 adults aged ≥45 y).

DESIGN

A modified Block 98 food-frequency questionnaire was used for dietary assessment in 21,636 participants, and nutritional variables were categorized by sex-specific quintiles. Normal weight, overweight, and obese were defined as BMI (in kg/m(2)) categories of 18.5-24.9, 25-29.9, and ≥30, respectively. Albuminuria was defined as a ratio (mg/g) of urinary albumin to creatinine of ≥30.

RESULTS

The prevalences of albuminuria were 11.5%, 11.6%, and 16.0% in normal-weight, overweight, and obese participants, respectively. The multivariable-adjusted ORs for albuminuria in a comparison of the highest with the lowest quintile of Na/K intake (≥1.12 to <0.70 for men and ≥1.07 to <0.62 for women) were 0.89 (95% CI: 0.65, 1.22), 1.08 (95% CI: 0.85, 1.36), and 1.28 (95% CI: 1.02, 1.61) in normal-weight, overweight, and obese participants, respectively. The highest quintile of dietary sodium was associated with an increased OR for albuminuria in obese participants (OR: 1.44; 95% CI: 1.00, 2.07) but not in normal-weight or overweight participants. Dietary potassium was not associated with albuminuria.

CONCLUSION

In obese adults, higher dietary Na/K and sodium intakes were associated with albuminuria.

Dietary habits and inadequate control of blood pressure in hypertensive adults assisted by a Brazilian Family Doctor Program

Objective

To estimate dietary habits and other factors associated with inadequate blood pressure (BP) control in hypertensive patients adherent to antihypertensive drug treatment assisted by a Brazilian Family Doctor Program (FDP).

Design

A cross-sectional study.

Setting

FDP units, Niterói, Rio de Janeiro, Brazil.

Subjects

We included data from both male and female participants aged ≥20 years. Participants completed a standardized questionnaire containing questions related to demographics, socio-economic factors, comorbidities and lifestyle, as well as a validated FFQ and eleven additional qualitative questions to investigate dietary habits. Food items were divided into sixteen groups. Medical consultations were performed, BP measurements were taken, blood and urine samples were assessed and anthropometric and nutritional status was evaluated.

Results

Individuals with inadequate BP control presented higher BMI values (prevalence ratio (PR) = 1·027, 95 % CI 1·009, 1·045) and also consumed more meat (PR = 1·091, 95 % CI 1·022, 1·165), which are potentially modifiable variables. Higher levels of serum creatinine (PR = 1·894, 95 % CI 1·241, 2·892) were also associated with inadequate BP control, as were skin colour (white). After inclusion of the Na excretion index, which is an indirect measure of salt intake, a slight decrease was observed in the PR for meat, which resulted in loss of statistical significance.

Conclusions

The results indicate that salt consumption, skin colour, BMI and serum creatinine are associated with inadequate BP control.

Mineralocorticoid receptor activation: a major contributor to salt-induced renal injury and hypertension in young rats

Excessive salt intake is known to preferentially increase blood pressure (BP) and promote kidney damage in young, salt-sensitive hypertensive human and animal models. We have suggested that mineralocorticoid receptor (MR) activation plays a major role in kidney injury in young rats. BP and urinary protein were compared in young (3-wk-old) and adult (10-wk-old) uninephrectomized (UNx) Sprague-Dawley rats fed a high (8.0%)-salt diet for 4 wk. The effects of the MR blocker eplerenone on BP and renal injury were examined in the high-salt diet-fed young UNx rats. Renal expression of renin-angiotensin-aldosterone (RAA) system components and of inflammatory and oxidative stress markers was also measured. The effects of the angiotensin receptor blocker olmesartan with or without low-dose aldosterone infusion, the aldosterone synthase inhibitor FAD286, and the antioxidant tempol were also studied. Excessive salt intake induced greater hypertension and proteinuria in young rats than in adult rats. The kidneys of young salt-loaded rats showed marked histological injury, overexpression of RAA system components, and an increase in inflammatory and oxidative stress markers. These changes were markedly ameliorated by eplerenone treatment. Olmesartan also ameliorated salt-induced renal injury but failed to do so when combined with low-dose aldosterone infusion. FAD286 and tempol also markedly reduced urinary protein. UNx rats exposed to excessive salt at a young age showed severe hypertension and renal injury, likely primarily due to MR activation and secondarily due to angiotensin receptor activation, which may be mediated by inflammation and oxidative stress.

Dietary sodium, aldosterone, and left ventricular mass changes during long-term inhibition of the renin-angiotensin system

In essential hypertension, the regression of left ventricular hypertrophy is an important goal of treatment. In addition to treatment-associated changes in blood pressure (BP), the roles of other determinants of left ventricular hypertrophy regression, including dietary sodium intake, deserve investigation. In the present study, the change in echographic left ventricular mass index (LVMI) was assessed in 182 patients with never-treated essential hypertension at baseline and after 3 years of treatment by angiotensin converting enzyme inhibitors or angiotensin II receptor antagonists given at recommended doses and associated with other antihypertensive agents. Treatment was associated with satisfactory control of BP (<140/90 mm Hg) in 64% of patients, and left ventricular hypertrophy prevalence decreased from 56% to 39%. Twenty-four-hour urinary sodium was positively related to LVMI at baseline and at the end of the study, independently of age, sex, and systolic BP. Supine plasma aldosterone concentration was correlated with LVMI only at baseline but not in multivariate analysis. In response to treatment, the percentage of change in LVMI was positively correlated with the absolute changes in systolic BP, urinary sodium, and plasma aldosterone concentration, independently of baseline LVMI. The population was divided into 3 tertiles according to final values of gender-specific urinary sodium. When, within each urinary sodium tertile, patients were divided into those with plasma aldosterone concentration below and above the median (11.6 ng/dL), LVMI progressively increased across sodium tertiles only in patients with high plasma aldosterone concentration. Systolic BP was similar across all of the groups. In conclusion, aldosterone requires the presence of high dietary salt for the expression of its unfavorable effect on the heart.

Disparate effects of eplerenone, amlodipine and telmisartan on podocyte injury in aldosterone-infused rats

BACKGROUND

Several studies in patients with primary aldosteronism (PA) have suggested that aldosterone (ALD) is directly contributing to albuminuria. However, there are limited data pertaining to the direct role of ALD in in vivo models in regard to the induction of renal injury and the involved mechanisms. In the present study, we established a high-dose ALD-infused rat model to evaluate urinary albumin excretion rate (UAER) and podocyte damage. Moreover, we studied the effect of eplerenone (EPL), telmisartan (TEL) and amlodipine (AML) on ALD-induced renal structural and functional changes.

METHODS

Immunohistochemical and real-time PCR analyses, and TUNEL assays were performed to evaluate nephrin expression and podocyte injury.

RESULTS

ALD-receiving rats (ARR) showed a progressive increase in BP, UAER and proteinuria when compared with control rats (CR). Conversely, BP was significantly reduced in ALD + EPL (A/ERR)-, ALD + AML (A/ARR)- and ALD + TEL (A/TRR)-treated rats. However, UAER and proteinuria were decreased only in A/ERR and A/TRR, but not in A/ARR. Only EPL administration provided protection against ALD-induced podocyte apoptosis. Renal tissue of ARR revealed enhanced expression of nephrin protein and mRNA. This effect of ALD was inhibited by EPL, but not by TEL or AML. Conclusions. ALD induces direct glomerular injury independent of its haemodynamic effects; this effect of ALD is, at least in part, mediated through activation of the mineralocorticoid receptor.

The role of aldosteronism in causing obesity-related cardiovascular risk

A large body of evidence strongly links aldosterone to development and progression of cardiovascular disease, including vascular stiffness, left ventricular hypertrophy, congestive heart failure, chronic kidney disease, and, especially, hypertension. Emerging data suggest that adipocytes may serve as a source of aldosterone, either directly or indirectly, through the release of aldosterone-stimulating factors. If adipocytes are confirmed to have an important contribution to hyperaldosteronism, it would have significant clinical implications in linking aldosterone to obesity-related increases in cardiovascular risk. Such a cause-and-effect situation would then provide the opportunity to reverse that risk with preferential use of aldosterone antagonists in obese patients.

Primary aldosteronism: an update

Primary aldosteronism (PA) is common with an estimated prevalence rate of 10% in subjects with essential hypertension and higher in those with resistant hypertension. As well as contributing to hypertension, aldosterone has detrimental effects on the heart, vasculature and kidneys as well as adverse metabolic effects leading to an excess of cardiovascular morbidity. Therefore, recognition and appropriate treatment of PA is of increasing importance. However, the diagnosis of PA and determination of subtype can be problematic. The purpose of this review is to provide an overview of the evidence supporting this increased prevalence of PA, explore the metabolic and cardiovascular consequences of aldosterone excess and discuss optimal diagnostic and therapeutic strategies of PA.

Determinants of kidney dysfunction: is vasopressin a new player in the arena?

Copeptin is a marker of endogenous vasopressin secretion. Population-based data of the PREVEND Study show that men and women with high plasma copeptin have a highly prevalent microalbuminuria in addition to the low level of hydration typical of persons with high vasopressin secretion. The association of plasma copeptin with microalbuminuria suggests that vasopressin might have a role in kidney dysfunction via effects on the permselectivity of the glomerulus and/or on tubular albumin reabsorption.

Role of aldosterone in the progression of chronic kidney disease and potential use of aldosterone blockade in children

Much focus has been placed on the role of the renin-angiotensin system as a mediator of the progression of chronic kidney disease. Novel therapeutic strategies to inhibit the negative impact of renin-angiotensin activation, including dual therapy with an angiotensin-converting enzyme inhibitor and an angiotensin-receptor blocker, have been suggested to achieve more complete disruption of the renin-angiotensin system. The role played by aldosterone, a target of angiotensin II, in the progression of chronic kidney disease has become a subject of significant interest over the past decade. Experimental studies in animals have shown that persistently elevated aldosterone levels lead to pathohistological changes in the kidney, along with renal and cardiac fibrosis. Incomplete suppression of aldosterone may, therefore, contribute to the deleterious effects of the renin-angiotensin system in the setting of chronic kidney disease. Clinical trials in adults have shown a potential role for mineralocorticoid receptor blockers to delay further the development of end-stage renal disease by completing renin-angiotensin blockade. In adults, mineralocorticoid receptor blockade produces a significant anti-proteinuric effect and has minimal risk of causing hyperkalemia if the condition of the patients is closely monitored. Further studies will need to be conducted to determine whether mineralocorticoid receptor blockers are equally effective and safe for the treatment of chronic kidney disease in children.

Aldosterone and cardiovascular disease

Aldosterone is an adrenal hormone that regulates sodium, fluid, and potassium balance. Jerome Conn first described the syndrome of autonomous and excessive aldosterone secretion or "primary aldosteronism." Contrary to the historical belief, recent studies indicate that primary aldosteronism is a common cause of hypertension with a prevalence of 5-10% among general hypertensive patients. Various animal models have demonstrated that aldosterone in association with a high salt diet results in target-organ inflammation and fibrosis. Similarly, cross-sectional and observational human studies have demonstrated the association of aldosterone with development and severity of hypertension, congestive heart failure, coronary artery disease, chronic kidney disease, and metabolic syndrome. Several interventional studies have also demonstrated the beneficial effects of mineralocorticoid receptor antagonists in these disease processes, particularly hypertension, heart failure, and post myocardial infarction, further supporting the role of aldosterone in their pathogenesis. We review the role of aldosterone in these various cardiovascular disease processes along with potential mechanisms and treatment.

Joint effects of sodium and potassium intake on subsequent cardiovascular disease: the Trials of Hypertension Prevention follow-up study

BACKGROUND

Previous studies of dose-response effects of usual sodium and potassium intake on subsequent cardiovascular disease (CVD) have largely relied on suboptimal measures of intake.

METHODS

Two trials of sodium reduction and other interventions collected 24-hour urinary excretions intermittently during 18 months from September 17, 1987, to January 12, 1990 (Trials of Hypertension Prevention [TOHP] I), and during 36 months from December 18, 1990, to April 7, 1995 (TOHP II), among adults with prehypertension aged 30 to 54 years. Among adults not assigned to an active sodium reduction intervention, we assessed the relationship of a mean of 3 to 7 twenty-four-hour urinary excretions of sodium and potassium and their ratio with subsequent CVD (stroke, myocardial infarction, coronary revascularization, or CVD mortality) through 10 to 15 years of posttrial follow-up.

RESULTS

Among 2974 participants, follow-up information was obtained on 2275 participants (76.5%), with 193 CVD events. After adjustment for baseline variables and lifestyle changes, there was a nonsignificant trend in CVD risk across sex-specific quartiles of urinary sodium excretion (rate ratio [RR] from lowest to highest, 1.00, 0.99, 1.16, and 1.20; P = .38 for trend) and potassium excretion (RR, 1.00, 0.94, 0.91, and 0.64; P = .08 for trend) but a significant trend across quartiles of the sodium to potassium excretion ratio (RR, 1.00, 0.84, 1.18, and 1.50; P = .04 for trend). In models containing both measures simultaneously, linear effects were as follows: RR, 1.42; 95% confidence interval (CI), 0.99 to 2.04 per 100 mmol/24 h of urinary sodium excretion (P = .05); and 0.67; 0.41 to 1.10 per 50 mmol/24 h of urinary potassium excretion (P = .12). A model containing the sodium to potassium excretion ratio (RR, 1.24; 95% CI, 1.05-1.46; P = .01) had the lowest Bayes information criterion (best fit).

CONCLUSION

A higher sodium to potassium excretion ratio is associated with increased risk of subsequent CVD, with an effect stronger than that of sodium or potassium alone.

Resistant hypertension and aldosteronism

Resistant hypertension is defined as blood pressure that remains uncontrolled despite using at least three antihypertensive medications in effective doses, ideally including a diuretic. Stricter blood pressure goals, higher obesity rates, older age, and increased use of certain exogenous substances are related to an increasing prevalence of resistant hypertension. The evaluation of patients with resistant hypertension focuses on identifying contributing factors and secondary causes of hypertension including hyperaldosteronism, obstructive sleep apnea, renal artery stenosis, and pheochromocytoma. Hyperaldosteronism is now recognized as the most common secondary cause and all patients with resistant hypertension should be screened with a plasma aldosterone-renin ratio even if the serum potassium level is normal. Treatment includes reversal of contributing factors, appropriate treatment of secondary causes, and use of effective multidrug regimens. Recent studies indicate that the addition of spironolactone to standard treatment regimens induces significant blood pressure reduction in patients with resistant hypertension.

Plasma aldosterone is related to severity of obstructive sleep apnea in subjects with resistant hypertension

OBJECTIVE

Obstructive sleep apnea (OSA) and primary aldosteronism are common in subjects with resistant hypertension; it is unknown, however, if the two disorders are causally related. This study relates plasma aldosterone and renin levels to OSA severity in subjects with resistant hypertension, and in those with equally severe OSA but without resistant hypertension serving as control subjects.

METHODS

Seventy-one consecutive subjects referred to the University of Alabama at Birmingham (UAB) for resistant hypertension (BP uncontrolled on three medications) and 29 control subjects referred to UAB Sleep Disorders Center for suspected OSA were prospectively evaluated by an early morning plasma aldosterone concentration (PAC) and renin level, and by overnight, attended polysomnography.

RESULTS

OSA (apnea-hypopnea index [AHI] > or = 5/h) was present in 85% of subjects with resistant hypertension. In these subjects, PAC correlated with AHI (rho = 0.44, p = 0.0002) but not renin concentration. Median PAC was significantly lower in control subjects compared to subjects with resistant hypertension (5.5 ng/dL vs 11.0 ng/dL, p < 0.05) and not related to AHI. In male subjects compared to female subjects with resistant hypertension, OSA was more common (90% vs 77%) and more severe (median AHI, 20.8/h vs 10.8/h; p = 0.01), and median PAC was significantly higher (12.0 ng/dL vs 8.8 ng/dL, p = 0.006).

CONCLUSION

OSA is extremely common in subjects with resistant hypertension. A significant correlation between PAC and OSA severity is observed in subjects with resistant hypertension but not in control subjects. While cause and effect cannot be inferred, the data suggest that aldosterone excess may contribute to OSA severity.