Diagnostic approach to low-renin hypertension

Transcriptome Study of 2 Black Cohorts Reveals cis Long Noncoding RNAs Associated With Hypertension-Related mRNAs

BACKGROUND

Long noncoding RNAs (lncRNAs) have emerged as critical regulators of the expression of genes involved in cardiovascular diseases. This project aims to identify circulating lncRNAs associated with protein-coding mRNAs differentially expressed between hypertensive and normotensive individuals and establish their link with hypertension.

METHODS AND RESULTS

The analyses were conducted in 3 main steps: (1) an unbiased whole blood transcriptome-wide analysis was conducted to identify and replicate protein-coding genes differentially expressed by hypertension status in 497 and 179 Black individuals from the GENE-FORECAST (Genomics, Environmental Factors and the Social Determinants of Cardiovascular Disease in African-Americans Study) and MH-GRID (Minority Health Genomics and Translational Research Bio-Repository Database) studies, respectively. Subsequently, (2) proximal lncRNAs, termed cis lncRNA quantitative trait loci, associated with each mRNA were identified in the GENE-FORECAST study and replicated in the MH-GRID study. Finally, (3) the lncRNA quantitative trait loci were used as predictors in a random forest model to predict hypertension in both data sets. A total of 129 mRNAs were significantly differentially expressed between normotensive and hypertensive individuals in both data sets. The lncRNA-mRNA association analysis revealed 249 cis lncRNA quantitative trait loci associated with 102 mRNAs, including VAMP2 (vesicle-associated membrane protein 2), mitogen-activated protein kinase kinase 3, CCAAT enhancer binding protein beta, and lymphocyte antigen 6 complex, locus E. The 249 lncRNA quantitative trait loci predicted hypertension with an area under the curve of 0.79 and 0.71 in GENE-FORECAST and MH-GRID studies, respectively.

CONCLUSIONS

This study leveraged a significant sample of Black individuals, a population facing a disproportionate burden of hypertension. The analyses unveiled a total of 271 lncRNA-mRNA relationships involving mRNAs that play critical roles in vascular pathways relevant to blood pressure regulation. The compelling findings, consistent across 2 independent data sets, establish a reliable foundation for designing in vitro/in vivo experiments.

Low Cortisone as a Novel Predictor of the Low-Renin Phenotype

A large proportion of patients with low-renin hypertension (LRH) correspond to primary aldosteronism (PA). However, some of these subjects have low to normal aldosterone. Since low renin is driven by excessive mineralocorticoids or glucocorticoids acting on mineralocorticoid receptors (MRs), we hypothesize that a low-cortisone condition, associated classically with 11βHSD2 deficiency, is a proxy of chronic MR activation by cortisol, which can also lead to low renin, elevated blood pressure, and renal and vascular alterations.

Objective

To evaluate low cortisone as a predictor of low renin activity and its association with parameters of kidney and vascular damage.

Methods

A cross-sectional study was carried out in 206 adult subjects. The subjects were classified according to low plasma renin activity (<1 ng/mL × hours) and low cortisone (<25th percentile).

Results

Plasma renin activity was associated with aldosterone (r = 0.36; P < .001) and cortisone (r = 0.22; P = .001). A binary logistic regression analysis showed that serum cortisone per ug/dL increase predicted the low-renin phenotype (OR 0.4, 95% CI 0.21-0.78). The receiver operating characteristic curves for cortisone showed an area under the curve of 0.6 to discriminate subjects with low renin activity from controls. The low-cortisone subjects showed higher albuminuria and PAI-1 and lower sodium excretion. The association study also showed that urinary cortisone was correlated with blood pressure and serum potassium (P < .05).

Conclusion

This is the first study showing that low cortisone is a predictor of a low-renin condition. Low cortisone also predicted surrogate markers of vascular and renal damage. Since the aldosterone to renin ratio is used in the screening of PA, low cortisone values should be considered additionally to avoid false positives in the aldosterone-renin ratio calculation.

Long-Term Follow-Up of Patients With Elevated Aldosterone-to-Renin Ratio but Negative Confirmatory Test: The Progression of Primary Aldosteronism Phenotypes

BACKGROUND

About 10% of patients with arterial hypertension have a positive screening test for primary aldosteronism (PA) and 50% to 70% of them have a negative confirmatory test: the appropriate follow-up of these patients is currently unknown. We investigated the incidence of PA in patients with previous negative confirmatory testing, after at least a 2-year follow-up.

METHODS

One hundred eighty-four patients with a previously elevated aldosterone-to-renin ratio followed by a negative confirmatory test were recruited in 2 hypertension centers (Torino and Munich). We repeated the screening test for PA and, if positive, the confirmatory test (seated saline infusion test or captopril challenge test). Primary end point of the study was the incidence of newly diagnosed overt PA, as defined by a positive confirmatory test.

RESULTS

After a mean follow-up of 5 years, 20% of patients developed overt PA. When subtype diagnosis was offered systematically, one-third of patients displayed unilateral PA. Patients who developed PA showed worsening of blood pressure control and a higher rate of cardiac organ damage, despite similar implementation of antihypertensive therapy, compared with patients without PA. A mild progression of autonomous aldosterone secretion was evident even in patients without confirmed PA but with relatively stable control of blood pressure levels over time.

CONCLUSIONS

About one-fifth of patients with a negative confirmatory test develop overt PA over time. A clinical follow-up of patients with a negative confirmatory test is advisable, along with the repetition of PA investigation, primarily in patients with worsening of blood pressure control.

RAS-challenge as a first-look test for detection of primary aldosteronism in patients with treatment-resistant hypertension

PURPOSE

Primary aldosteronism (PA), characterised by low-renin hypertension, confers a high cardiovascular risk and is the most common cause of secondary hypertension, with an increased prevalence in patients with treatment-resistant hypertension. However, it is estimated that only a small percentage of affected patients are identified in routine clinical practice. Inhibitors of the renin-angiotensin system cause an increase in renin levels in patients with intact aldosterone regulation, and inadequate low renin with concurrent RAS inhibition (RASi) may therefore indicate PA, which could serve as a first look screening test for selection for formal work-up.

METHODS

We analysed patients between 2016-2018 with treatment-resistant hypertension who had inadequate low renin in the presence of RASi (i. e. at risk for PA) and who were offered systematic work-up with adrenal vein sampling (AVS).

RESULTS

A total of 26 pts were included in the study (age 54.8 ± 11, male 65%). Mean office blood pressure (BP) was 154/95 mmHg on 4.5 antihypertensive drug classes. AVS had a high technical success rate (96%) and demonstrated unilateral disease in the majority of patients (57%), most of which (77%) were undetected by cross-sectional imaging.

CONCLUSION

In patients with resistant hypertension, low renin in the presence of RASi is a strong indicator for autonomous aldosterone secretion. It may serve as an on-medication screening test for PA to select for formal PA work up.

The mechanism underlying fluoride-induced low-renin hypertension is related to an imbalance in the circulatory and local renin-angiotensin systems

The renin-angiotensin system (RAS) is an important fluid regulation system in the body, and excessive activation of the circulatory or local RAS can increase blood pressure (BP). Excess fluoride can increase BP, although the underlying mechanism related to activation of the RAS remains unclear. Thus, the aim of this study was to elucidate the role of the RAS in fluoride-induced hypertension. Markers of the circulating and local RASs related to pathological changes to the kidneys, myocardium, and aorta were measured. Fluoride reduced serum levels of renin, angiotensin II (Ang II), and angiotensin (1-7) [Ang (1-7)], and dysregulated plasma levels of aldosterone and potassium levels. Excess fluoride can damage the kidneys, myocardium, and aorta, overactivate the renal angiotensin converting enzyme (ACE)-Ang II-angiotensin type 1 receptor axis, and inhibit activation of the ACE2-Ang (1-7)-Mas axis, leading to dysregulation of alpha epithelial sodium channels and significantly increased expression of Ang II in the myocardium and aorta. Hence, excess fluoride can cause low-renin hypertension via an imbalance between the circulatory and local RASs.

Approach to the Patient on Antihypertensive Therapy: Screen for Primary Aldosteronism

Primary aldosteronism (PA) is a condition that is still largely overlooked, resulting in a considerable burden of mortality and morbidity. This is despite decades of clinical and translational research on the deleterious effects of aldosterone on the cardiovascular system and the publication of several guidelines and consensuses on its diagnosis and treatment. One of the main reasons for the low rate of testing is the difficulty of screening patients on antihypertensive therapy that potentially interferes with aldosterone and renin levels and thus confound the interpretation of the aldosterone to renin ratio, the accepted and conventionally used screening test. To avoid interference, usually the therapies that affect the renin-angiotensin aldosterone system are withdrawn and substituted with noninterfering medications. However, in many cases the screening test can be confidently interpreted even when such therapies are not discontinued. In this review, we will evaluate the effects of antihypertensive therapies on the screening test for PA and suggest a practical approach for its interpretation.

Chinese normotensive and essential hypertensive reference intervals for plasma aldosterone and renin activity by liquid chromatography-tandem mass spectrometry

OBJECTIVES

The renin-angiotensin-aldosterone system (RAAS) regulates blood pressure. Plasma renin activities (PRA) and plasma aldosterone concentrations (PAC) are biomarkers related to RAAS. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based measurements for PRA and PAC have become popular. Method-specific reference intervals (RIs) are required.

METHODS

Routine PRA and PAC services in a Hong Kong teaching hospital were based on LC-MS/MS methods. PRA and PAC RIs were developed for normotensive subjects and essential hypertensive (EH) patients. Healthy volunteers were recruited to establish normotensive RIs. PRA and PAC results of hypertensive patients with urine aldosterone tests for primary aldosteronism (PA) screening were retrieved from the laboratory information system. Patients without PA were included. Patients with secondary hypertension and patients on medications affecting the RAAS were excluded. The central 95% RIs were established based on the recommendations of the Clinical and Laboratory Standards Institute guideline C28-A3.

RESULTS

PRA and PAC of 170 normotensive volunteers and 362 EH patients were analysed. There was no sex-specific difference in PRA and PAC for normotensive and EH reference subjects. Differences for PRA and PAC were noted between normotensive subjects aged below 45 and their older counterparts. However, such a difference was only identified for PRA but not PAC in EH patients. Age-specific RIs were established accordingly.

CONCLUSIONS

This study presented age-specific LC-MS/MS RIs of PRA and PAC for both normotensive and EH populations for local Chinese in Hong Kong.

Concurrent Primary Aldosteronism and Renal Artery Stenosis: An Overlooked Condition Inducing Resistant Hypertension

To explore the clinical features of coexisting primary aldosteronism (PA) and renal artery stenosis (RAS), we retrospectively analyzed records from 71 patients with PA with RAS and a control group of 121 patients with PA without RAS. Aldosterone-to-renin concentration ratio tests and computerized tomography (CT) scanning of the adrenal and renal arteries were routinely conducted to screen for PA and RAS. Color Doppler flow and/or magnetic resonance imaging were used as substitute testing of patients for whom CT was contraindicated. Standard percutaneous renal arteriography (PTRA) was considered for patients with RAS exceeding 70% based on non-invasive tests and for those without PTRA contraindications. The patients with PA with RAS were further divided into severe (RAS>70%) and moderate (50% < RAS <70%) RAS groups. The prevalence of RAS among PA patients was 6.9% (71/1,033), including 3.2% (33/1,033) with severe RAS. Compared with the PA without RAS group, the severe RAS group showed higher levels of systolic blood pressure (SBP) (171.82 ± 18.24 vs. 154.11 ± 18.96 mmHg; P < 0.001) and diastolic BP(DBP) (110.76 ± 15.90 vs. 91.73 ± 12.85 mmHg; P < 0.001) and prevalence of resistant hypertension (RH) (90.9 vs. 66.9%; P = 0.008), whereas the moderate RAS group merely showed higher DBP (98.63 ± 14.90 vs. 91.73 ± 12.85 mmHg; P = 0.006). The direct renin concentrations (DRCs) (5.37 ± 3.94 vs. 3.71 ± 2.10 μU/mL; P < 0.001) and false-negative rate (33.8 vs. 3.3%; P < 0.01) of PA screening tests were significantly higher in the PA with RAS group than in the control group, but only in severe RAS group, in subgroup analysis. Among patients who underwent successful treatment for severe RAS, mean DRC decreased from 11.22 ± 9.10 to 3.24 ± 2.69 μIU/mL (P < 0.001). Overall, the prevalence of RH decreased from 81.7 to 2.8% (P < 0.001) when both PA and RAS were treated with standard methods. PA with concurrent severe RAS is a condition that induces RH. PA can be easily missed in patients with coexisting RAS. RAS patients with RH after successful revascularization for RAS should be evaluated for coexisting PA.

Increasing Incidence of Primary Aldosteronism in Western Sweden During 3 Decades - Yet An Underdiagnosed Disorder

CONTEXT

Primary aldosteronism (PA) is the most common cause of secondary hypertension. Yet, the incidence of PA in the general population has not been studied.

OBJECTIVE

To estimate the incidence of PA in the general population.

DESIGN AND METHODS

Patients who had received a diagnostic code for PA between 1987 and 2016 were identified in the Swedish National Patient Registry. Assessment of clinical and biochemical data was used to validate the diagnosis. The annual incidence of PA was calculated by using the number of inhabitants in the Västra Götaland County as a reference.

RESULTS

Of 570 identified patients, 473 (83%) had confirmed PA. Eligible for the incidence analysis were 416 patients, 248 (60%) men and 168 (40%) women, diagnosed with PA between 1987 and 2016. The mean (± standard deviation) age at diagnosis was 56 ± 12 years. The median (interquartile range) annual incidence was 2 (1-2) cases per million between 1987 and 1996, 6 (4-9) cases per million between 1997 and 2006 and 17 (12-24) cases per million between 2007 and 2016. At the end of the study (December 31, 2016), 386 patients with confirmed PA were alive and living in the Västra Götaland County, giving a prevalence of 231 cases per million (0.022%).

CONCLUSIONS

Despite increasing incidence, the proportion of patients identified with PA is lower than expected. Given the serious consequences of untreated PA, the noticeably low prevalence at the end of the study stresses the need to increase the awareness of PA among health care providers.

Antifungal therapy with azoles and the syndrome of acquired mineralocorticoid excess

The syndromes of mineralocorticoid excess describe a heterogeneous group of clinical manifestations leading to endocrine hypertension, typically either through direct activation of mineralocorticoid receptors or indirectly by impaired pre-receptor enzymatic regulation or through disturbed renal sodium homeostasis. The phenotypes of these disorders can be caused by inherited gene variants and somatic mutations or may be acquired upon exposures to exogenous substances. Regarding the latter, the symptoms of an acquired mineralocorticoid excess have been reported during treatment with azole antifungal drugs. The current review describes the occurrence of mineralocorticoid excess particularly during the therapy with posaconazole and itraconazole, addresses the underlying mechanisms as well as inter- and intra-individual differences, and proposes a therapeutic drug monitoring strategy for these two azole antifungals. Moreover, other therapeutically used azole antifungals and ongoing efforts to avoid adverse mineralocorticoid effects of azole compounds are shortly discussed.

Myocardial mechano-energetic efficiency in primary aldosteronism

BACKGROUND

Available data indicate that patients with primary aldosteronism have an increased risk of cardiovascular events and cardiovascular risk seems to be, at least in part, independent of blood pressure (BP) values. Patients with primary aldosteronism have a greater prevalence of left ventricular (LV) hypertrophy and subtle alterations of ventricular function, which might contribute to the increase in cardiovascular risk. Recently, a noninvasive approach for the estimation of LV mechanical efficiency, obtained by echocardiography has been proposed.

AIM OF THE STUDY

To evaluate the determinants of myocardial mechanoenergetic efficiency index (MEEi), in a large group of patients with primary aldosteronism (n = 99) and in a control group of essential hypertensive patients (n = 99) matched for age, sex and BP values.

RESULTS

No differences between groups for age, sex, BMI, BP values, glucose, lipid profile and renal function were observed. LV mass index was greater in primary aldosteronism vs. essential hypertensive patients (46.0 ± 16.7 vs. 36.9 ± 8.6 g/m2, P < 0.001); also relative wall thickness was greater in primary aldosteronism (0.36 ± 0.1 vs. 0.32 ± 0.4, P < 0.001). Left atrial dimensions were significantly greater in primary aldosteronism. Ejection fraction was not different between groups, while endocardial and midwall fractional shortening were lower in primary aldosteronism vs. essential hypertensive patients (40 ± 7 vs. 43 ± 6, and 18 ± 3 vs. 21 ± 2, both P < 0.01). MEEi was lower in primary aldosteronism vs. essential hypertensive patients (0.44 ± 0.14 vs. 0.52 ± 0.10 ml/s per g, P < 0.01). A negative correlation was observed between MEEi and aldosterone levels (r = -0.203, P < 0.05) and aldosterone : renin ratio (P = -0.172, P < 0.05); the correlation remained significant after adjustment for possible confounders.

CONCLUSION

In patients with primary aldosteronism myocardial MEEi is lower as compared with essential hypertensive patients. A reduced MEEi may reflect an impairment of production and utilization of energy in the myocardium, which could lead to the occurrence of cardiovascular complications and therefore these findings may contribute to explain the increased risk of cardiovascular events in patients with primary aldosteronism.

Aldosterone sensitivity: an opportunity to explore the pathogenesis of hypertension

Aldosterone sensitivity is defined as an outcome variable for a given circulating level of aldosterone. In basic and translational studies, aldosterone sensitivity has been measured in differential tissue responses, e.g., lower urine sodium and higher urine potassium, as an index of the renal response; in clinical studies, aldosterone sensitivity has been measured in differential blood pressure responses. The concept of aldosterone sensitivity disrupts the conventional wisdom of the renin-angiotensin-aldosterone system and has the potential to uncover novel mechanisms of hypertension. Here, we review basic and translational science studies that uncovered differential renal responses to aldosterone and connect this earlier work to more recent observational studies and randomized trials that have demonstrated differential blood pressure responses for a given level of aldosterone in healthy and hypertensive persons. Black race and older age are associated with higher aldosterone sensitivity and blood pressure. We also discuss gaps in the field and how future basic and clinical studies might inform mechanisms of differential sensitivity.

The value of the post-captopril aldosterone/renin ratio for the diagnosis of primary aldosteronism and the influential factors: A meta-analysis

OBJECTIVE

The procedure for the captopril challenge test (CCT) in diagnosing primary aldosteronism (PA) is not standardized. We performed a meta-analysis to evaluate the controversial diagnostic value and influential factors of the post-captopril aldosterone/renin ratio (ARR).

METHODS

We searched literature in databases for eligible studies (until October 1, 2020). We extracted information regarding study and patient characteristics, CCT methods, outcome data. We pooled studies using the random-effect model. We performed meta-regression and six pre-specified subgroup analyses to explore heterogeneity.

RESULTS

Nineteen studies involving 4568 subjects were included. The pooled sensitivity and specificity were 0.825 (95% CI 0.804-0.844) and 0.919 (95% CI 0.908-0.928). The area under the summary receiver operating characteristic curve was 0.9487 (95% CI 0.9207-0.9767). Meta-regression revealed that heterogeneity might derive from time interval (p = 0.0117) and study population (p = 0.0033). Subgroup analyses showed significant differences between the subgroups stratified by the dose, posture, study region, time interval, cut-off value and study population for sensitivity and/or specificity (p < 0.05).

CONCLUSION

Post-captopril ARR is comparably valuable for diagnosing PA at cut-offs from 12.0 to 50.0. Conducting the CCT in the supine position with 25 mg of captopril may attain greater sensitivity. Conducting the CCT in the seated position with 50 mg of captopril may attain greater specificity. A 90-min time interval may perform best in both the sensitivity and specificity.

Trick or Treat? Licorice-Induced Hypokalemia: A Case Report

The by-products of black licorice metabolism are toxic in high concentrations. Patients who consume large quantities of black licorice are at risk of developing an acquired syndrome of apparent mineralocorticoid excess. This presents clinically as hypertension, hypernatremia, and hypokalemia. Here, we present the unique case of a 74-year-old woman with a past medical history of neurogenic orthostatic hypotension, on fludrocortisone, who presented to the emergency department with asymptomatic hypokalemia (2.4 mmol/L) as detected in outpatient laboratory studies. During her hospital stay, it was discovered that the patient was consuming excessive amounts of black licorice. With this information, the synergistic interaction of fludrocortisone and black licorice was recognized as the cause of the patient's severe hypokalemia. The patient's fludrocortisone was stopped and she was treated with multiple courses of potassium repletion. Upon discharge, her fludrocortisone was discontinued, and she was prescribed midodrine to treat her neurogenic orthostatic hypertension. While small amounts of black licorice are safe, excessive licorice consumption can cause severe disease. Our case presents an opportunity to appreciate the plethora of etiologies for severe hypokalemia and the importance of taking a thorough patient history to avoid potentially fatal clinical outcomes.

Endocrine causes of heart failure: A clinical primer for cardiologists

Heart failure (HF) may be a presenting manifestation of a few endocrine disorders and should be considered in evaluation of heart failure causes. This clinically oriented review is an attempt to highlight the protean manifestations of heart failure in endocrine diseases which could present either as acute or chronic heart failure. Acute heart failure manifests as hypertensive crisis, Takotsubo syndrome, or as tachy/brady cardiomyopathies. Chronic heart failure could masquerade with features of hyperdynamic heart failure, or hypertrophic, restrictive or dilated cardiomyopathy. Rarely constrictive features or resistant heart failure could be the presenting feature. Isolated presentation as pulmonary hypertension and right heart failure are also documented. Good history-taking and physical examination with targeted investigations will help in the timely management for reversing the pathophysiology to a significant extent by appropriated management.

Genetics, prevalence, screening and confirmation of primary aldosteronism: a position statement and consensus of the Working Group on Endocrine Hypertension of The European Society of Hypertension

: Autonomous aldosterone overproduction represents the underlying condition of 5-10% of patients with arterial hypertension and carries a significant burden of mortality and morbidity. The diagnostic algorithm for primary aldosteronism is sequentially based on hormonal tests (screening and confirmation tests), followed by lateralization studies (adrenal CT scanning and adrenal venous sampling) to distinguish between unilateral and bilateral disease. Despite the recommendations of the Endocrine Society guideline, primary aldosteronism is largely underdiagnosed and undertreated with high between-centre heterogeneity. Experts from the European Society of Hypertension have critically reviewed the available literature and prepared a consensus document constituting two articles to summarize current knowledge on the epidemiology, diagnosis, treatment, and complications of primary aldosteronism.

The spectrum of low-renin hypertension

Low-renin hypertension (LRH) is a frequent condition in patients with arterial hypertension, accounting for 30% of patients. Monogenic forms can cause LRH in a minority of cases. However, in the large majority of patients, LRH is caused by the combined effects of congenital and acquired factors, comprising dietary habits. Several genetic variants have been proposed as co-factors in the pathogenesis of LRH with normal-low serum aldosterone. Emerging evidences support the hypothesis that a large proportion of LRH with normal-high serum aldosterone is associated with subclinical primary aldosteronism (PA). The recent identification of aldosterone-producing cell clusters (APCCs) as the possible cause of subclinical PA, further supported the concept of a continuous spectrum of autonomous aldosterone secretion, from subclinical forms towards overt PA. In this review we describe the main aspects of LRH, focusing on molecular basis, clinical risk profile and patients' management.

Prevalence of Hypokalemia and Primary Aldosteronism in 5100 Patients Referred to a Tertiary Hypertension Unit

Primary aldosteronism (PA) was considered a rare disorder almost always associated with hypokalemia. The widespread screening of patients with hypertension unveiled an increased prevalence of PA with normokalemic hypertension the prevailing phenotype. Many studies have reported the prevalence of hypokalemia in patients with PA; conversely, the prevalence of PA in patients with hypokalemia is unknown. In this retrospective observational study, we define the prevalence of hypokalemia in referred patients with hypertension and the prevalence of PA in patients with hypokalemia and hypertension. Hypokalemia was present in 15.8% of 5100 patients with hypertension, whereas 76.9% were normokalemic, and 7.3% hyperkalemic. The prevalence of PA in patients with hypokalemia was 28.1% and increased with decreasing potassium concentrations up to 88.5% of patients with spontaneous hypokalemia and potassium concentrations <2.5 mmol/L. A multivariate regression analysis demonstrated the association of hypokalemia with the occurrence of cardiovascular events independent of PA diagnosis. An association of PA with the occurrence of cardiovascular events and target organ damage independent of hypokalemia was also demonstrated. In conclusion, our results confirm that PA is a frequent cause of secondary hypertension in patients with hypokalemia, and the presence of hypertension and spontaneous hypokalemia are strong indications for PA diagnosis. Finally, we show that PA and hypokalemia are associated with an increased risk of cardiovascular events.

Basal Plasma Aldosterone Concentration Predicts Therapeutic Outcomes in Primary Aldosteronism

Purpose

Normal basal plasma aldosterone concentration (PAC) reflects mild aldosterone excess compared to high basal PAC. We previously reported lower risk for cardiovascular and cerebrovascular events in patients with primary aldosteronism (PA) and normal basal PAC (nPA) than in those with high basal PAC (hPA). However, the differences in therapeutic outcomes between nPA and hPA are unclear. The aim of this multi-institutional, retrospective cohort study was to determine the clinical significance of nPA to therapeutic outcomes, including adrenalectomy (ADX) and treatment with mineralocorticoid receptor antagonists (MRAs).

Methods

A total of 1146 patients with PA who were diagnosed and underwent adrenal venous sampling (AVS) between January 2006 and October 2016 were enrolled. The clinical parameters at baseline and after ADX or treatment with MRA were compared between the nPA and hPA groups.

Results

Significantly higher rates of absent clinical success (36.6 vs. 21.9%, P = 0.01) and absent biochemical success (26.4 vs. 5.2%, P < 0.01) were found for the nPA group than for the hPA group, respectively. Logistic regression analysis identified baseline PAC as a significant independent predictor of absent clinical success of ADX and MRAs.

Conclusions

Plasma aldosterone concentration at baseline was a significant and independent predictor of absent clinical success of ADX and MRA. Mineralocorticoid receptor antagonist treatment appeared to be a better therapeutic choice than ADX in the nPA group.

Primary aldosteronism in a general population sample. The Czech post-MONICA study

Purpose: Primary aldosteronism (PA) is considered the most common form of secondary hypertension, however, its prevalence, particularly in a general population, is still a matter of debate. The aim of our study was to evaluate the prevalence of PA in a randomly selected general population sample.Materials and methods: A total of 1940 individuals (1% population random sample) aged 25-64 years were screened for major cardiovascular risk factors in six districts of the Czech Republic. Hypertension was defined as a mean of two blood pressure readings ≥140/90 mmHg at one visit or taking antihypertensive medication. Within this population, 740 individuals were labelled as hypertensives and 650 of them sampled for the analysis of direct plasma renin and serum aldosterone. The diagnosis of PA was based on elevated serum aldosterone, low plasma renin and high aldosterone/renin (ARR) ratio and was also verified by a confirmatory test with saline infusion.Results: Positive ARR was found in 52 (8%) individuals (64% women, 36% men, however, due to substatntial proportion of reluctatnt participants to undergo a further work-up (27%), we could confirm the diagnosis of PA only in 13 of them (2%). Aldosterone-producing adenoma was found in one case only, seven patients had idiopathic type and five individuals refused potential surgical treatment therefore, adrenal venous sampling was not performed.Conclusion: Elevated serum aldosterone together with low renin and high ARR were found in 52 (8%) of hypertensives selected from a general population sample, however, the diagnosis of PA was confirmed only in 13 of them (2%). This study based on a general population survey highlighted the difficulty of conducting epidemiological studies on primary aldosteronism in a relatively healthy cohort part of whom did not provide the level of collaboration that is necessary to assess the true prevalence of this condition.

Renin-Angiotensin-Aldosterone System Triple-A Analysis for the Screening of Primary Aldosteronism

Primary aldosteronism is recognized as the most frequent cause of secondary hypertension, and its screening is expected to become a routine evaluation in most patients with hypertension. The interference of antihypertensive therapies with the aldosterone-to-renin ratio during screening process is a major confounder. Renin-angiotensin-aldosterone system Triple-A analysis is a novel liquid chromatography/tandem mass spectrometry diagnostic assay that allows simultaneous quantification of aldosterone, equilibrium Ang I (angiotensin I), and Equilibrium Ang II in a single sample of serum. We performed a comparative evaluation of the diagnostic performance of the aldosterone-to-Ang II ratio and 5 renin-based diagnostic ratios, differing in methods to determine aldosterone levels and renin activity in a cohort of 110 patients with hypertension (33 patients with confirmed primary aldosteronism and 77 with essential hypertension). All ratios showed comparable areas under the curves ranging between 0.924 and 0.970 without significant differences between each other. The evaluation of the Ang II-to-Ang I ratio revealed persistent drug intake in some patients as cause for suppressed renin-based diagnostic ratios, while aldosterone-to-Ang II ratio remained unaffected. The Youden index optimal cutoff value for the aldosterone-to-Ang II ratio was 6.6 ([pmol/L]/[pmol/L]) with a sensitivity of 90% and a specificity of 93%, proving noninferiority compared with the aldosterone-to-renin ratio while pointing to the potential for an interference-free application in patients under ACE (angiotensin-converting enzyme) inhibitor therapy. This study shows for the first time the accuracy and reliability of renin-angiotensin-aldosterone system triple-A analysis for the screening of primary aldosteronism that can be applied in clinical routine.

Resistant Hypertension: A Clinical Perspective

Resistant hypertension is a common clinical entity, defined as suboptimal blood pressure response to multiple therapies after excluding medication nonadherence and secondary forms of hypertension. Patients with resistant hypertension generally share several comorbidities. Resistant hypertension is more common in individuals of African descent. Blood pressure should be optimized using multiple strategies, including lifestyle changes and single-pill combination therapies, with the aim of reducing cardiovascular events while reducing side effects from using antihypertensive therapy. A renin/aldosterone-based diagnostic and treatment approach will help tailor therapy. The use of mineralocorticoid receptor antagonists or amiloride as appropriate is favored.

Low-Renin Hypertension

Low-renin hypertension affects 30% of hypertensive patients. Primary hyperaldosteronism presents with low renin and aldosterone excess. Low-renin, low-aldosterone hypertension represents a wide spectrum of disorders that includes essential low-renin hypertension, hereditary forms of hypertension, and hypertension secondary to endogenous or exogenous factors. This review addresses the different conditions that present with low-renin hypertension, discussing an appropriate diagnostic approach and highlighting the genetic subtypes within familial forms.

Genetics of Hypertension in African Americans and Others of African Descent

Hypertension is the leading cause of cardiovascular disease in the United States, affecting up to one-third of adults. When compared to other ethnic or racial groups in the United States, African Americans and other people of African descent show a higher incidence of hypertension and its related comorbidities; however, the genetics of hypertension in these populations has not been studied adequately. Several genes have been identified to play a role in the genetics of hypertension. They include genes regulating the renin-aldosterone-angiotensin system (RAAS), such as Sodium Channel Epithelial 1 Beta Subunit (SCNN1B), Armadillo Repeat Containing 5 (ARMC5), G Protein-Coupled Receptor Kinase 4 (GRK4), and Calcium Voltage-Gated Channel Subunit Alpha1 D (CACNA1D). In this review, we focus on recent genetic findings available in the public domain for potential differences between African Americans and other populations. We also cover some recent and relevant discoveries in the field of low-renin hypertension from our laboratory at the National Institutes of Health. Understanding the different genetics of hypertension among various groups is essential for effective precision-guided medical therapy of high blood pressure.

Aldosterone-Producing Adenomas

Aldosterone-producing adenomas (APA) are more common than initially anticipated. APA cause primary aldosteronism (PA), which affect 3-10% of the hypertensive population. Research during recent years has led to an increased knowledge of the background dysregulation of the increased aldosterone release, where mutation in the gene encoding the potassium channel GIRK4-KCNJ5-is the most common. Moreover, the discovery of aldosterone-producing cell clusters in apparently normal adenomas has also led to increased understanding of the development of PA, and presumably also APA. A continuum ranging from low-renin hypertension to APA and overt PA is reasoned, and the secondary effects of aldosterone on especially the cardiovascular system have also become more evident. Diagnostics of PA and APA is important in order to reduce cardiovascular morbidity and mortality, but the diagnostic methods are somewhat unspecific and insensitive, indicating the need for novel methods.

Genetics and pathophysiology of low-renin arterial hypertension

The review is devoted to the consideration of genetic determination and pathophysiology of one of the forms of hypertensive disease known as low-renin hypertension. At frst glance, the development of low-renin hypertension is “unnatural”, as renin, as a key enzyme of the renin-angiotensin system, which plays an important role in the development of hypertensive disease, is suppressed in low-renin hypertension. At the same time, the most important drugs actual in the treatment of hypertensive disease belong to the renin-angiotensin system blockers. This contradiction was resolved by a study of genetic and pathophysiological mechanisms of hypertension in some groups of patients with characteristic symptoms bringing these people together. Genetic studies of some recent decades using both family analysis and modern molecular genetic technologies have revealed the main mechanisms underlying low-renin hypertension, which can be classifed as certain syndromes with well-defned genetic and clinical features. These syndromes include cases of sporadically occurring somatic mutations in the cells of the adrenal cortex, which begin to produce aldosterone in increased amounts. Also, several oligogenic forms of low-renin hypertension were studied, some of which are associated with the hyperproduction of aldosterone, but in the others the development of low-renin hypertension was associated with mutations of genes involved in regulation of the functioning of the kidney ion channels. The discovery of some types of arterial hypertension with known mechanisms of their development is of paramount importance for medicine, as it allows for targeted efective therapy and in some cases for achieving a complete cure. However, the main contingent of patients with low-renin hypertension belongs to cases with unexplained etiology, as their development is associated with polygenic systems and with a signifcant influence of numerous environmental factors. The study of genetic and physiological mechanisms of various forms of low-renin arterial hypertension provides a good example of how penetration into the intimate mechanisms of the blood pressure regulation in each personal case makes it possible to identify some specifc syndromes and establish its fnal causes. It seems that progress in understanding the causes and mechanisms of essential hypertension lies along this way.

The Expanding Spectrum of Primary Aldosteronism: Implications for Diagnosis, Pathogenesis, and Treatment

Primary aldosteronism is characterized by aldosterone secretion that is independent of renin and angiotensin II and sodium status. The deleterious effects of primary aldosteronism are mediated by excessive activation of the mineralocorticoid receptor that results in the well-known consequences of volume expansion, hypertension, hypokalemia, and metabolic alkalosis, but it also increases the risk for cardiovascular and kidney disease, as well as death. For decades, the approaches to defining, diagnosing, and treating primary aldosteronism have been relatively constant and generally focused on detecting and treating the more severe presentations of the disease. However, emerging evidence suggests that the prevalence of primary aldosteronism is much greater than previously recognized, and that milder and nonclassical forms of renin-independent aldosterone secretion that impart heightened cardiovascular risk may be common. Public health efforts to prevent aldosterone-mediated end-organ disease will require improved capabilities to diagnose all forms of primary aldosteronism while optimizing the treatment approaches such that the excess risk for cardiovascular and kidney disease is adequately mitigated. In this review, we present a physiologic approach to considering the diagnosis, pathogenesis, and treatment of primary aldosteronism. We review evidence suggesting that primary aldosteronism manifests across a wide spectrum of severity, ranging from mild to overt, that correlates with cardiovascular risk. Furthermore, we review emerging evidence from genetic studies that begin to provide a theoretical explanation for the pathogenesis of primary aldosteronism and a link to its phenotypic severity spectrum and prevalence. Finally, we review human studies that provide insights into the optimal approach toward the treatment of primary aldosteronism.