Primary Aldosteronism and Resistant Hypertension: A Pathophysiological Insight

Primary and "Pre-Primary" Aldosteronism in Resistant Hypertension: A Practical, Pragmatic, and Prudent Approach in Resource-Limited Milieu

Introduction Primary aldosteronism (PA), once considered rare, is now recognized as the most common cause of secondary hypertension, accounting for almost a quarter of resistant hypertension (RH) cases. Despite this, PA remains underdiagnosed, with an extremely low percentage of RH patients undergoing screening. Methods In a specialty diabetes-endocrinology clinic, the aldosterone:renin ratio (ARR) was assessed in 115 consecutive RH patients (ages 21-93 years; 47% male; 87% with type 2 diabetes). Fasting blood samples were drawn in a standing position after 30 minutes of walking. Adrenal imaging (CT/MRI) was performed for those with an ARR >20. Results ARR values ranged from 0.4 to 227 (ARR <10 (35%); 11-20 (19%), 21-40 (25%), and >40 (21%)), with corresponding stepwise decreasing plasma renin activity (PRA) (P= 1E-6) and increasing serum aldosterone (SA) (P= 8E-7). Increasing ARR tended to be associated with an increase in serum creatinine (R= 0.23; P= 0.03) and a decrease in estimated glomerular filtration rate (eGFR) (R= -0.24; P= 0.02) and an increase in urine albumin: creatinine ratio. The ARR> 40 group displayed the highest serum creatinine, lowest eGFR, higher urine albumin: creatinine ratio, highest serum sodium, lowest serum potassium, and highest (44%) abnormal adrenal imaging (bilateral hyperplasia diffuse/nodular; solitary adenoma), reflecting a later stage of the pathological spectrum. PA treatment with mineralocorticoid receptor antagonists (MRAs) had a salutary effect. Conclusions Our observations further reinforce that PA is not a binary condition, but exists as a spectrum disorder responsive to MRAs, even in patients with mildly elevated or normal aldosterone levels. Early disease detection/recognition ("renin-independent aldosterone production") can be facilitated by marking "pre-primary" aldosteronism (ARR 11-20), followed by monitoring progression (periodic rescreening) and optimizing treatment, with hopeful mitigation of end-organ damage in RH.

Prevalence of Normal-Tension Glaucoma in Patients With Primary Aldosteronism

PURPOSE

To investigate patients with primary aldosteronism (PA) and the prevalence of normal-tension glaucoma (NTG).

DESIGN

Cross-sectional study.

METHODS

Newly diagnosed PA patients were evaluated in this cross-sectional study, with ophthalmic examinations such as intraocular pressure measurements by a Goldmann applanation tonometer, central corneal thickness, slit-lamp biomicroscopic examination, gonioscopy, ophthalmoscopy, fundus photography, visual field test with a Humphrey Field Analyzer 24-2 SITA Standard program, and optical coherence tomography of the peripapillary retinal nerve fiber layer, performed in each of the subjects. Optic disc appearance, perimetric results, optical coherence tomography results, and other ocular findings were all used for determining the glaucoma diagnosis. The primary outcome was shown the prevalence of NTG in patients with PA.

RESULTS

NTG prevalence in the 212 PA patients was 11.8% (95% confidence interval [CI], 4.7%-20.7%). As compared to the hypertensive patients without PA, the hypertensive patients with PA exhibited a significantly increased NTG prevalence (odds ratio; 4.019, 95% CI, 1.223-13.205; P = .022). Increased NTG prevalence was associated with age, ranging from 8.8% (95% CI, 2.1%-15.6%) for those aged 40 to 49 years, to 37.5% (95% CI, 13.8%-61.2%) for those aged 70 years and older. In 72 hypertensive patients without PA, who were used as the controls, NTG prevalence was 5.2%, with a 95% CI ranging from 0.5% to 14.4%.

CONCLUSIONS

There was an 11.8% prevalence of NTG in PA patients, with these patients at an elevated risk of NTG, which was not mediated by blood pressure.

Genetic testing for familial hyperaldosteronism type 1 in Aotearoa/New Zealand

BACKGROUND

Primary aldosteronism (PA) is the most common secondary endocrine cause of hypertension with familial hyperaldosteronism type 1 (FH-1), a rare heritable subtype. Timely identification of FH-1 is important because of an increased risk of vascular events in affected individuals and because it provides the opportunity to guide appropriate treatment. Genetic testing is recommended if onset is at a young age (<20 years), there is a family history of PA or early cerebrovascular events occur.

AIMS

To assess national rates of testing for FH-1, whether this varied over time and by region.

METHODS

De-identified data were obtained on genetic testing performed for FH-1 from 1 April 2010 to 30 October 2023 (163 months) from the Canterbury Health Laboratories database, the sole national testing laboratory for FH-1.

RESULTS

A total of 147 tests were performed, of which 19 (12.9%) were positive. Eleven of the positive tests were requested by one region. Testing rates varied from 0.00 to 0.63 per 100 000 people per annum. Most tests were requested by endocrinology services. Testing increased over time from an average of 4.6 tests per annum in the first 5 years of the period studied to 17.7 tests in the most recent 5 years. Limitations include lack of ethnicity data, information on testing indications and testing rates for other familial PA subtypes.

CONCLUSIONS

Testing for FH-1 has increased over time but remains low. Testing for familial forms of PA should be considered in those in whom PA was diagnosed at a young age or with a suggestive family history.

Selective venous sampling for secondary hypertension

Selective venous sampling (SVS), an invasive radiographic procedure that depends on contrast media, holds a unique role in diagnosing and guiding the treatment of certain types of secondary hypertension, particularly in patients who may be candidates for curative surgery. The adrenal venous sampling (AVS), in particular, is established as the gold standard for localizing and subtyping primary aldosteronism (PA). Throughout decades of clinical practice, AVS could be applied not only to PA but also to other endocrine diseases, such as adrenal Cushing syndrome (ACS) and Pheochromocytomas (PCCs). Notably, the application of AVS in ACS and PCCs remains less recognized compared to PA, with the low success rate of catheterization, the controversy of results interpretation, and the absence of a standardized protocol. Additionally, the AVS procedure necessitates enhancements to boost its success rate, with several helpful but imperfect methods emerging, yet continued exploration remains essential. We also observed renal venous sampling (RVS), an operation akin to AVS in principle, serves as an effective means of diagnosing renin-dependent hypertension, aiding in the identification of precise sources of renin excess and helping the selection of surgical candidates with renin angiotensin aldosterone system (RAAS) abnormal activation. Nonetheless, further basic and clinical research is needed. Selective venous sampling (SVS) can be used in identifying cases of secondary hypertension that are curable by surgical intervention. Adrenal venous sampling (AVS) and aldosterone measurement for classificatory diagnosis of primary aldosteronism (PA) are established worldwide. While its primary application is for PA, AVS also holds the potential for diagnosing other endocrine disorders, including adrenal Cushing's syndrome (ACS) and pheochromocytomas (PCCs) through the measurements of cortisol and catecholamine respectively. In addition, renal venous sampling and renin measurement can help to diagnose renovascular hypertension and reninoma.

Mineralocorticoid receptor overactivation: targeting systemic impact with non-steroidal mineralocorticoid receptor antagonists

The overactivation of the mineralocorticoid receptor (MR) promotes pathophysiological processes related to multiple physiological systems, including the heart, vasculature, adipose tissue and kidneys. The inhibition of the MR with classical MR antagonists (MRA) has successfully improved outcomes most evidently in heart failure. However, real and perceived risk of side effects and limited tolerability associated with classical MRA have represented barriers to implementing MRA in settings where they have been already proven efficacious (heart failure with reduced ejection fraction) and studying their potential role in settings where they might be beneficial but where risk of safety events is perceived to be higher (renal disease). Novel non-steroidal MRA have distinct properties that might translate into favourable clinical effects and better safety profiles as compared with MRA currently used in clinical practice. Randomised trials have shown benefits of non-steroidal MRA in a range of clinical contexts, including diabetic kidney disease, hypertension and heart failure. This review provides an overview of the literature on the systemic impact of MR overactivation across organ systems. Moreover, we summarise the evidence from preclinical studies and clinical trials that have set the stage for a potential new paradigm of MR antagonism.

Role of SARS-COV-2 and ACE2 in the pathophysiology of peripheral vascular diseases

The occurrence of a novel coronavirus known as severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), created a serious challenge worldwide. SARS-CoV-2 has high infectivity, the ability to be transmitted even during the asymptomatic phase, and relatively low virulence, which has resulted in rapid transmission. SARS-CoV-2 can invade epithelial cells, hence, many patients infected with SARS-CoV-2 have suffered from vascular diseases (VDs) in addition to pulmonary manifestations. Accordingly, SARS-CoV-2 may can worsen the clinical condition of the patients with pre-existing VDs. Endothelial cells express angiotensin-converting enzyme 2 (ACE2). ACE2 is a biological enzyme that converts angiotensin (Ang)- 2 to Ang-(1-7). SARS-CoV-2 uses ACE2 as a cell receptor for viral entry. Thus, the SARS-CoV-2 virus promotes downregulation of ACE2, Ang-(1-7), and anti-inflammatory cytokines, as well as, an increase in Ang-2, resulting in pro-inflammatory cytokines. SARS-CoV-2 infection can cause hypertension, and endothelial damage, which can lead to intravascular thrombosis. In this review, we have concentrated on the effect of SARS-CoV-2 in peripheral vascular diseases (PVDs) and ACE2 as an enzyme in Renin-angiotensin aldosterone system (RAAS). A comprehensive search was performed on PubMed, Google Scholar, Scopus, using related keywords. Articles focusing on ("SARS-CoV-2", OR "COVID-19"), AND ("Vascular disease", OR "Peripheral vascular disease", OR interested disease name) with regard to MeSH terms, were selected. According to the studies, it is supposed that vascular diseases may increase susceptibility to severe SARS-CoV-2 infection due to increased thrombotic burden and endothelial dysfunction. Understanding SARS-CoV-2 infection mechanism and vascular system pathogenesis is crucial for effective management and treatment in pre-existing vascular diseases.

Advances in the Pathogenesis and Treatment of Resistant Hypertension

Hypertension is a prevalent chronic disease associated with an increased risk of cardiovascular (CV) premature death, and its severe form manifests as resistant hypertension (RH). The accurate prevalence of resistant hypertension is difficult to determine due to the discrepancy in data from various populations, but according to recent publications, it ranges from 6% to 18% in hypertensive patients. However, a comprehensive understanding of the pathogenesis and treatment of RH is essential. This review emphasizes the importance of identifying the causes of treatment resistance in antihypertensive therapy and highlights the utilization of appropriate diagnostic methods. We discussed innovative therapies such as autonomic neuromodulation techniques like renal denervation (RDN) and carotid baroreceptor stimulation, along with invasive interventions such as arteriovenous anastomosis as potential approaches to support patients with inadequate medical treatment and enhance outcomes in RH.

Primary Aldosteronism and Drug Resistant Hypertension: A "Chicken-Egg" Story

Drug-resistant arterial hypertension (RH) is a major risk factor for cardiovascular disease, often due to overlooked underlying causes. Identification of such causes poses significant clinical challenges. In this setting, primary aldosteronism (PA) is a frequent cause of RH and its prevalence in RH patients is likely higher than 20%.The pathophysiological link between PA and the development and maintenance of RH involves target organ damage and the cellular and extracellular effects of aldosterone excess that promote pro-inflammatory and pro-fibrotic changes in the kidney and vasculature.The feasibility of adrenal vein sampling in PA patients with RH, and the clinical benefit achieved by adrenalectomy, further emphasize the need to implement systematic screening for this common form of secondary hypertension in the management of a high-risk population as RH patients.: We herein review the current knowledge of the factors that contribute to the RH phenotype with a focus on PA and discuss the issues regarding the screening for PA in this setting and the therapeutic approaches (surgical and medical) aimed at resolving RH caused by PA.

Predictive performance of aldosterone-to-renin ratio in the diagnosis of primary aldosteronism in patients with resistant hypertension

Background

The systematic use of confirmatory tests in the diagnosis of primary aldosteronism (PA) increases costs, risks and complexity to the diagnostic work-up. In light of this, some authors proposed aldosterone-to-renin (ARR) cut-offs and/or integrated flow-charts to avoid this step. Patients with resistant hypertension (RH), however, are characterized by a dysregulated renin-angiotensin-aldosterone system, even in the absence of PA. Thus, it is unclear whether these strategies might be applied with the same diagnostic reliability in the setting of RH.

Methods

We enrolled 129 consecutive patients diagnosed with RH and no other causes of secondary hypertension. All patients underwent full biochemical assessment for PA, encompassing both basal measurements and a saline infusion test.

Results

34/129 patients (26.4%) were diagnosed with PA. ARR alone provided a moderate-to-high accuracy in predicting the diagnosis of PA (AUC=0.908). Among normokalemic patients, the ARR value that maximized the diagnostic accuracy, as identified by the Youden index, was equal to 41.8 (ng/dL)/(ng/mL/h), and was characterized by a sensitivity and a specificity of 100% and 67%, respectively (AUC=0.882); an ARR > 179.6 (ng/dL)/(ng/mL/h) provided a 100% specificity for the diagnosis of PA, but was associated with a very low sensitivity of 20%. Among hypokalemic patients, the ARR value that maximized the diagnostic accuracy, as identified by the Youden index, was equal to 49.2 (ng/dL)/(ng/mL/h), and was characterized by a sensitivity and a specificity of 100% and 83%, respectively (AUC=0.941); an ARR > 104.0 (ng/dL)/(ng/mL/h) provided a 100% specificity for the diagnosis of PA, with a sensitivity of 64%.

Conclusions

Among normokalemic patients, there was a wide overlap in ARR values between those with PA and those with essential RH; the possibility to skip a confirmatory test should thus be considered with caution in this setting. A better discriminating ability could be seen in the presence of hypokalemia; in this case, ARR alone may be sufficient to skip confirmatory tests in a suitable percentage of patients.

Diagnostic value of the fractional excretion of urine potassium for primary aldosteronism

Background

Primary aldosteronism (PA) is a common form of secondary hypertension, which usually manifests low blood potassium levels. The fractional excretion of urine potassium (FEK) has been proposed as a useful tool to measure urinary potassium excretion. However, the role of the FEK in PA remains unclear. In the current study, we assessed the diagnostic value of FEK in PA.

Methods

A total of 155 hypertension patients were included in this cross-sectional study, of which 62 were confirmed by a positive screening test for PA. We collected the serum, 24-hr urine samples, and spot urine samples to evaluate the diagnostic value of the spot and 24-hr FEK in the diagnosis of PA and renal potassium loss compared to other indices. The sensitivity and specificity of the related diagnostic indexes were analyzed using receiver operating characteristic (ROC) curves, and the optimal cut-point value of the diagnostic index was determined according to the Youden index (YI) (sensitivity + specificity - 1). Correlation analysis was performed between the spot FEK and 24-hr FEK using Pearson's correlation coefficient.

Results

The spot FEK (7.3 vs. 5.9) and 24-hr FEK (9.3 vs. 8.0) levels were statistical differences between the PA and essential hypertension groups. PA patients had a significant tendency to lose potassium through the kidneys. We found that FEK from spot urine distinguished renal potassium loss with a sensitivity of 86.7% and a specificity of 87.1% at a cut-off of 9.8%. The sensitivity and specificity of the spot FEK in screening PA were 51.6% and 76.3%, respectively.

Conclusions

FEK is significantly related to renal potassium loss. Spot FEK and 24-hr FEK performed a certain diagnostic value for PA, which may be potential indicators for the differential diagnosis of PA.

The role of aldosterone in the pathogenesis of diabetic retinopathy

Aldosterone, as a mineralocorticoid of adrenal origin, has effects that are not limited to the urinary tract. As an important regulator in Vasoactive hormone pathways, aldosterone may play an effect in the pathogenesis of diabetic retinopathy (DR) through the regulation of oxidative stress, vascular regulation, and inflammatory mechanisms. This implies that mineralocorticoids, including aldosterone, have great potential and value for the diagnosis and treatment of DR. Because early studies did not focus on the intrinsic association between mineralocorticoids and DR, targeted research is still in its infancy and there are still many obstacles to its application in the clinical setting. Recent studies have improved the understanding of the effects of aldosterone on DR, and we review them with the aim of exploring possible mechanisms for the treatment and prevention of DR.

Aldosterone as a Possible Contributor to Eye Diseases

Aldosterone, an effector molecule of the renin-angiotensin-aldosterone system (RAAS), has been receiving more attention in the field of ophthalmology because of its possible role in the pathogenesis of various eye diseases or abnormalities; it may even become a target for their treatment. Primary aldosteronism, a typical model of a systemic aldosterone excess, may cause vision loss due to various ocular diseases, such as retinal vein occlusion, central serous chorioretinopathy, and, possibly glaucoma. RAAS components are present in various parts and types of cells present in the eye. Investigations of the local RAAS in various animal models of diabetic macular edema, retinal vein occlusion, retinopathy of prematurity, central serous chorioretinopathy, and glaucoma have found evidence that aldosterone or mineralocorticoid receptors may exacerbate the pathology of these disorders. Further studies are needed to elucidate whether the modulation of aldosterone or mineralocorticoid receptors is an effective treatment for preventing vision loss in patients with eye diseases.

Adipose Tissue Dysfunction in Obesity: Role of Mineralocorticoid Receptor

The mineralocorticoid receptor (MR) acts as an essential regulator of blood pressure, volume status, and electrolyte balance. However, in recent decades, a growing body of evidence has suggested that MR may also have a role in mediating pro-inflammatory, pro-oxidative, and pro-fibrotic changes in several target organs, including the adipose tissue. The finding that MR is overexpressed in the adipose tissue of patients with obesity has led to the hypothesis that this receptor can contribute to adipokine dysregulation and low-grade chronic inflammation, alterations that are linked to the development of obesity-related metabolic and cardiovascular complications. Moreover, several studies in animal models have investigated the role of MR antagonists (MRAs) in preventing the metabolic alterations observed in obesity. In the present review we will focus on the potential mechanisms by which MR activation can contribute to adipose tissue dysfunction in obesity and on the possible beneficial effects of MRAs in this setting.