Active renin mass concentration (ARC) is independent of the endogenous level of angiotensinogen, and less variable and more reproducible than plasma renin activity. Reference values for the aldosterone-to-renin ratio (ARR) using ARC are still undefined. The objective of the present study was to determine the threshold of ARR using ARC measurement to screen for primary aldosteronism.
A total of 211 subjects were included in the study, comprising 78 healthy normotensive controls, 95 patients with essential hypertension, and 38 patients with confirmed primary aldosteronism (20 with surgery-confirmed aldosterone-producing adenoma and 18 with idiopathic adrenal hyperplasia). Blood samples were drawn from ambulatory patients and volunteers in the mid-morning without specific dietary restriction for measuring plasma aldosterone concentration, ARC, and serum potassium.
Most normotensive controls and essential hypertension patients had ARR results below 100 pmol/ng, a value which corresponded to 3.3 times the median of these two groups.
Patients with ARR values above this level should be considered for further investigation (confirmatory tests) or for repeat testing should ARR values be borderline. This study indicates that ARC can be used reliably in determining ARR for primary aldosteronism screening.
primary aldosteronism; active renin mass concentration; aldosterone-to-renin ratio
Objective. Primary aldosteronism (PA) is associated with inappropriate left ventricular hypertrophy (LVH) in relation to a given gender and body size. There is no ideal parameter to predict the presence of LVH or inappropriate LVH in patients with PA. We investigate the performance of 24-hour urinary aldosterone level, plasma renin activity and aldosterone-to-renin ratio on this task. Methods. We performed echocardiography in 106 patients with PA and 31 subjects with essential hypertension (EH) in a tertiary teaching hospital. Plasma renin activity, aldosterone concentration, and 24-hour urinary aldosterone level were measured. Results. Only 24-hour urinary aldosterone was correlated with left ventricular mass index (LVMI) and excess LVMI among these parameters. The multivariate analysis revealed the urinary aldosterone level as an independent predictor for LVMI and excess LVMI. Analyzing the ability of urinary aldosterone, plasma aldosterone concentration, and plasma aldosterone-to-renin ratio to identify the presence of LVH (ROC AUC = 0.701, 0.568, 0.656, resp.) and the presence of inappropriate LV mass index (defined as measured LVMI in predicting LVMI ratio >135%) (ROC area under curve = 0.61, 0.43, 0.493, resp.) revealed the better performance of 24-hour urinary aldosterone. Conclusions. In conclusion, 24-hour urinary aldosterone level performed better to predict the presence of LVH and inappropriate LVMI in patients with PA.
Confirmatory testing of suspected primary aldosteronism (PA) requires an extensive medication switch that can be difficult for patients with severe complicated hypertension and/or refractory hypokalemia. For this reason, we investigated the effect of chronic antihypertensive medication on confirmatory testing results. To allow the results to be interpreted, the reproducibility of confirmatory testing was also evaluated.
Design and methods
The study enrolled 114 individuals with suspected PA who underwent two confirmatory tests. The patients were divided into two groups. In Group A, both tests were performed on the guidelines-recommended therapy, i.e. not interfering with the renin–angiotensin–aldosterone system. In Group B, the first test was performed on chronic therapy with the exclusion of thiazides, loop diuretics, and aldosterone antagonists; and the second test was performed on guidelines-recommended therapy. Saline infusion, preceded by oral sodium loading, was used to suppress aldosterone secretion.
Agreement in the interpretation of the two confirmatory tests was observed in 84 and 66% of patients in Groups A and B respectively. For all 20 individuals in Group A who ever had end-test serum aldosterone levels ≥240 pmol/l, aldosterone was concordantly nonsuppressible during the other test. Similarly, for all 16 individuals in Group B who had end-test serum aldosterone levels ≥240 pmol/l on modified chronic therapy, aldosterone remained nonsuppressible with guidelines-recommended therapy.
Confirmatory testing performed while the patient is on chronic therapy without diuretics and aldosterone antagonists can confirm the diagnosis of PA, provided serum aldosterone remains markedly elevated at the end of saline infusion.
Availability and wider application of the plasma aldosterone/renin ratio (ARR) as a screening test for primary aldosteronism (PA) has led to the recognition that PA is the most common potentially curable and specifically treatable form of hypertension, possibly accounting for as many as 5–13% of patients. Aldosterone excess also has adverse cardiovascular consequences that go above and beyond hypertension development. These findings support the concept that PA plays an important role in cardiovascular disease states and should be systematically sought and specifically treated, and have led to the development of a US Endocrine Society clinical guideline for the detection, diagnosis and management of this condition. Reliable detection requires that interfering factors (including medications known to alter the ratio) are controlled before ARR measurement (or their effects taken into account), and reliable methods such as fludrocortisone suppression testing are used to confirm PA. Because computed tomography frequently misses aldosterone-producing adenomas yet demonstrates non-functioning nodules, adrenal venous sampling is the only dependable way to differentiate unilateral (surgically correctable) from bilateral (usually treated with aldosterone antagonist medications) forms of PA. For the glucocorticoid-remediable form of PA (familial hyperaldosteronism type I), genetic testing for the causative ‘hybrid’ 11beta-hydroxylase/aldosterone synthase gene has greatly facilitated detection. Laboratory assessment (including suppression testing post-operatively, and renin measurement during treatment with aldosterone antagonist medications) can assist in assessing therapeutic responses and in guiding ongoing management. Development of new, highly reliable high-throughput mass spectrometric methods for measuring aldosterone and renin should further enhance detection and reliability of diagnostic workup for PA.
High blood pressure is an important determinant of cardiovascular disease risk. Treated hypertensives do not attain a risk level equivalent to normotensives. This may be a consequence of suboptimal blood pressure control to which indiscriminate use of antihypertensive drugs may contribute. Indeed the recent ALLHATstudy suggests that thiazides should be given first to virtually all hypertensives. Whether this is correct or whether different antihypertensive therapies should be targeted towards different patients is a major unresolved issue, which we address in this study.
The measurement of the ratio of aldosterone: renin is used to identify hypertensive subjects who may respond well to treatment with the aldosterone antagonist spironolactone. It is not known if subjects with a high ratio have aldosteronism or aldosterone-sensitive hypertension is debated but it is important to know whether spironolactone is superior to other diuretics such as bendroflumethiazide in this setting.
The study is a double-blind, randomised, crossover, controlled trial that will randomise 120 hypertensive subjects to 12 weeks treatment with spironolactone 50 mg once daily and 12 weeks treatment with bendroflumethiazide 2.5 mg once daily. The 2 treatment periods are separated by a 2-week washout period. Randomisation is stratified by aldosterone: renin ratio to include equal numbers of subjects with high and low aldosterone: renin ratios.
Primary Objective – To test the hypothesis that the aldosterone: renin ratio predicts the antihypertensive response to spironolactone, specifically that the effect of spironolactone 50 mg is greater than that of bendroflumethiazide 2.5 mg in hypertensive subjects with high aldosterone: renin ratios.
Secondary Objectives – To determine whether bendroflumethiazide induces adverse metabolic abnormalities, especially in subjects with high aldosterone: renin ratios and if baseline renin measurement predicts the antihypertensive response to spironolactone and/or bendrofluazide
The numerous deleterious effects of hypertension dictate the need for a systematic approach for its treatment. In spite of various therapies, resistant hypertension is widely prevalent. Among various factors, primary aldosteronism is an important cause of resistant hypertension and is now more commonly recognised. More significantly, hypertensives with primary aldosteronism are also exposed to various other deleterious effects of excess aldosterone. Hence treating hypertension with specific aldosterone antagonists may be a better approach in this group of patients. It may lead on to better blood pressures with fewer medications.
To evaluate the prevalence of primary aldosteronism (PA) in newly diagnosed and untreated hypertensive patients in primary care using the aldosterone/renin ratio (ARR), and to assess clinical and biochemical characteristics in patients with high and normal ARR.
Patient survey study.
Setting and subjects
A total of 200 consecutive patients with newly diagnosed and untreated hypertension from six primary health care centres in Sweden were included.
Main outcome measures
ARR was calculated from serum aldosterone and plasma renin concentrations. The cut-off level for ARR was 65. Patients with an increased ARR were considered for confirmatory testing with the fludrocortisone suppression test (FST), followed by adrenal computed tomographic radiology (CT) and adrenal venous sampling (AVS).
Of 200 patients, 36 patients had an ARR > 65. Of these 36 patients, 11 patients had an incomplete aldosterone inhibition during FST. Three patients were diagnosed with an aldosterone producing adenoma (APA) and eight with bilateral adrenal hyperplasia (BHA). Except for moderately lower level of P-K in patients with an ARR > 65 and in patients with PA, there were no biochemical or clinical differences found among hypertensive patients with PA compared with patients without PA.
Eleven of 200 evaluated patients (5.5%) were considered to have PA. The diagnosis of PA should therefore be considered in newly diagnosed hypertensive subjects and screening for the diagnosis is warranted.
Aldosterone; aldosterone to renin ratio; family practice; hypertension; primary aldosteronism; renin
Objective. We retrospectively analyzed all primary aldosteronism (PA) patients undergoing NP-59 SPECT/CT imaging with regard to their clinicolaboratory and imaging features, investigation, and outcomes. Material and Methods. 11 PA patients who presented to our hospital for NP-59 SPECT/CT imaging between April 2007 and March 2012 and managed here were analyzed. Results. Among 11 PA patients, eight (73%) had stage 1 hypertension, three (27%) stage 2 hypertension, four (36%) normal plasma aldosterone concentration, nine (82%) nonsuppressed plasma renin activity (PRA), six (55%) normal aldosterone-renin-ratio (ARR), eight (73%) serum potassium ≧3 mEq/L, seven (64%) subclinical presentation, seven (64%) negative confirmatory testing, and four (36%) inconclusive results on CT scan and seven (64%) on planar NP-59 scan. All 11 (100%) patients had positive results on NP-59 SPECT/CT scan. Two (18%) met typical triad and nine (82%) atypical triad. Among nine atypical PA patients, three (33%) had clinical presentation, six (67%) subclinical presentation, six (67%) negative confirmatory testing, and four (44%) inconclusive results on CT scan and six (67%) on planar NP-59 scan. All patients had improved outcomes. Significant differences between typical and atypical PA existed in PRA and ARR. Conclusions. NP-59 SPECT/CT may provide diagnostic potential in stage 1 hypertensive and atypical PA.
Resistant hypertension is a major opportunity for prevention of cardiovascular disease. Despite widespread dissemination of consensus guidelines, most patients are uncontrolled with approaches that assume that all patients are the same.
Causes of resistant hypertension include 1) non-compliance 2) consumption of substances that aggravate hypertension (such as salt, alcohol, nonsteroidal anti-inflammatory drugs, licorice, decongestants) and 3) secondary hypertension.
Selecting the appropriate therapy for a patient depends on finding the cause of the hypertension. Once rare causes have been eliminated (such as pheochromocytoma, licorice, adult coarctation of the aorta), the cause will usually be found by intelligent interpretation (in the light of medications then being taken) of plasma renin and aldosterone.
If stimulated renin is low and the aldosterone is high, the problem is primary aldosteronism, and the best treatment is usually aldosterone antagonists (spironolactone or eplerenone; high-dose amiloride for men where eplerenone is not available). If the renin is high, with secondary hyperaldosteronism, the best treatment is angiotensin receptor blockers or aliskiren. If the renin and aldosterone are both low the problem is over-activity of renal sodium channels and the treatment is amiloride. This approach is particularly important in patients of African origin, who are more likely to have low-renin hypertension.
Resistant hypertension; renin; amiloride; primary hyperaldosteronism; renal sodium channel; African-American; Stroke belt.
Angiotensin infusion evokes marked increases in aldosterone secretion in primary aldosteronism and little change in secondary aldosteronism. The low plasma renin activity of primary aldosteronism and the elevated plasma renin activity of secondary aldosteronism are thought to account for this differential response. The effect of angiotensin on aldosterone and 18-hydroxycorticosterone secretion was studied during adrenal vein catheterization in seven patients with primary aldosteronism (whose plasma renin activity had been elevated following spironolactone therapy), one hypertensive patient with normal plasma renin activity and normal aldosterone secretion, two patients with secondary aldosteronism who had elevated plasma renin activity, and one anephric patient whose plasma renin activity was 0. Adrenal venous aldosterone and 18-hydroxycorticosterone were measured before and after a ten min sub-pressor angiotensin infusion.
The cells of the aldosterone-producing adenoma (APA) respond to small increases in plasma angiotensin with large increases in secretion of aldosterone and 18-hydroxycorticosterone. The dose of angiotensin capable of evoking this response from the aldosterone-producing adenoma produces little or no change in the secretion of the steroids from nontumorous glands. The augmentation of aldosterone secretion, induced by angiotensin, in primary aldosteronism is due solely to increased secretion by the adenoma and not by the contralateral zona glomerulosa. The increased sensitivity of the aldosterone-producing adenoma is characteristic of the tumor. This response is independent of fluctuations in endogenous plasma renin activity. This sensitivity is not blunted by high plasma renin activity, nor is it a function of tumor mass for the effect is observed in aldosterone-producing adenomas regardless of size. ACTH injection after angiotensin infusion resulted in a marked increase in aldosterone concentration in the effluent from the nontumorous adrenal, but was not capable of producing further increases in aldosterone concentration in the effluent from the APA. In view of this exquisite sensitivity to infused angiotensin, it may be that the small variations in endogenous plasma renin activity that have been observed in primary aldosteronism may be capable of evoking large changes in aldosterone secretion in patients with aldosterone-producing adenomas.
A dopaminergic mechanism has been proposed to suppress aldosterone secretion. To assess the possibility that a defect in the dopaminergic mechanism might enhance aldosterone secretion in hypertensive patients, we determined basal and adrenocorticotropic hormone (ACTH)-stimulated plasma aldosterone (PA), cortisol, renin activity, and potassium concentrations before and during dopamine receptor stimulation with dopamine infusion and bromocriptine administration and dopamine receptor blockade with metoclopramide. The patient study groups included: (a) seven patients with low-renin hypertension and abnormal aldosterone suppression with sodium loading and presumed bilateral zona glomerulosa hyperplasia (ZGHP); (b) two patients with aldosterone-producing adenoma; (c) five patients with low-renin hypertension but normal aldosterone suppression with sodium loading; and (d) six patients with normal-renin hypertension. Dopamine infusion in patients with ZGHP caused PA to fall (P less than 0.01) into the normal range, but did not block the enhanced (P less than 0.05) aldosterone response to ACTH that is characteristic of these patients. Dopamine infusion in patients with low-renin hypertension but normal aldosterone suppression also suppressed PA (P less than 0.01), whereas it had no effect upon PA in patients with normal-renin hypertension or aldosterone-producing adenoma and did not blunt the PA response to ACTH in either group. Bromocriptine administration had no effect upon basal or ACTH-stimulated PA. Dopamine infusion in patients with ZGHP also enhanced (P less than 0.05) diuresis and natriuresis in comparison with normal-renin patients. Metoclopramide administration increased (P less than 0.01) PA in all patients. Thus, a dopaminergic mechanism appears to be important in the regulation of aldosterone secretion in patients with ZGHP and in other low-renin hypertensives with normal aldosterone suppression with sodium loading. In contrast, this latter group does not exhibit an enhanced aldosterone response to ACTH. Both of these groups differ from normal-renin hypertensives, who have no PA suppression with dopamine infusion.
Primary aldosteronism is the most common form of endocrine hypertension affecting approximately 8~10% of hypertensive subjects. Aldosterone production in PA occurs under low-renin conditions and the mechanisms that maintain the production of aldosterone in PA remain unknown.
This study was designed to compare the transcript profiles between aldosterone-producing adenoma (APA) and their adjacent adrenal gland (AAG) from the same adrenal.
Total RNA was extracted from 10 APA and 10 AAG; and subsequently analyzed by microarray and real-time quantitative RT-PCR (qPCR). The microarray data was paired for each APA-AAG, and analyzed by GeneSpring GX 11 with paired t-test and fold change calculations for each transcript. Changes identified by microarray analysis were confirmed by qPCR.
Microarray analysis indicated that 14 genes had significantly up-regulated expression in APA compared to AAG. Among genes elevated were aldosterone synthase (CYP11B2) as well as novel transcription factors, calmodulin binding proteins, and other genes that have not been previously studied in APA. Selective analysis of 11 steroidogenic enzymes using microarray demonstrated that only CYP11B2 showed a significantly higher transcript level in APA compared to AAG (P<0.001). In contrast, AKR1C3 (17β-hydroxysteroid dehydrogenase type 5), CYP17 (17α-hydroxylase/17, 20 lyase), and CYB5 (cytochrome b5) showed significantly lower transcript level in APA (P<0.05).
The transcriptome analysis of APA compared with AAG showed several novel genes that are associated with APA phenotype. This gene list provides new candidates for the elucidation of the molecular mechanisms leading to PA.
Transcriptome; aldosterone-producing adenoma; adjacent adrenal gland; biomarker
We studied the characteristics of insulin resistance in 19 normotensive and 25 hypertensive subjects who underwent an acute protocol for determination of salt-sensitivity of blood pressure. Hypertensive subjects were older and more obese, with higher creatinine, lipids and aldosterone than normotensive volunteers. They also had higher glucose and insulin levels with a marked decrease in insulin sensitivity (HOMA2-S index). Once all participants were classified into salt-sensitive (SS) and salt-resistant (SR) groups, most of these differences were no longer present. In contrast, SS had classical characteristics of this phenotype (higher percentage of blacks, suppressed plasma renin, increased aldosterone-to-renin ratio and blunted renin and aldosterone responses to changes in salt balance). Despite similar insulin levels, HOMA2-S was significantly lower in SS than SR. Salt loading did not change HOMA2-S in SS or SR. In contrast, salt depletion, by significantly increasing glucose and insulin of SR, decreased their HOMA2-S to the levels observed in SS. Correlates of insulin resistance in SR included age, triglycerides, BMI, mean arterial pressure, aldosterone and epinephrine. However, only BMI and aldosterone remained as significant predictors in multivariate analyses. Correlates of insulin resistance in SS were mean arterial pressure, epinephrine and norepinephrine, all remaining as significant predictors in multivariate modeling. Our data confirm that salt sensitivity of blood pressure is associated with insulin resistance, suggest that salt restriction may be beneficial in SS but perhaps detrimental in SR subjects, and uncover possible differences in mechanisms of insulin resistance between SS and SR, with implications for pharmacological therapy.
Insulin action; insulin resistance; salt-sensitive; renin angiotensin system; aldosterone; catecholamine; obesity
The existence of unilateral adrenal hyperplasia (AH) has been considered a rare cause of primary hyperaldosteronism (PA).
In a prospective study we screened for PA in a non-selected (NSP) and selected hypertensive population (SP), to define the cause of PA. We included 353 consecutive patients with hypertension; age 20 to 88 years, 165 women and 188 men, from a university-based Hypertension and Nephrology Outpatient clinics (123 SP) and two primary care centres, (230 NSP) from the same catch-up area. Serum aldosterone and plasma renin activity (PRA) were measured and the ARR calculated. Verifying diagnostic procedure was performed in patients with both elevated aldosterone and ARR. Patients diagnosed with PA were invited for adrenal venous sampling (AVS) and offered laparoscopic adrenalectomy when AVS found the disease to be unilateral.
After screening, 46 patients, 13% of the whole population (22.8% SP and 7.8% NSP) had aldosterone and ARR above the locally defined cut-off limits (0.43 nmol/l and 1.28 respectively). After diagnostic verification, 20 patients (6%) had PA, (14.5% SP and 1.4% NSP). Imaging diagnostic procedures with CT-scans and scintigraphy were inconclusive. AVS, performed in 15 patients verified bilateral disease in 4 and unilateral in 10 patients. One AVS failed. After laparoscopic adrenalectomy, 4 patients were found to have adenoma and 5 unilateral AH. One patient denied operation.
The prevalence of PA was in agreement with previous studies. The study finds unilateral PA common and unilateral AH as half of those cases. As may be suspected PA is found in much higher frequency in specialised hypertensive units compared to primary care centers. AVS was mandatory in diagnosis of unilateral PA.
Endocrine hypertension; Hyperaldosteronism; Aldosterone; Renin; Hypertension; Resistant hypertension; Adrenal hyperplasia
Plasma levels of renin, angiotensin II and aldosterone are increased during normal pregnancy. However, these values in preeclampsia are decreased to nearly that of a nonpregnant subject, and vascular sensitivity to angiotensin II is increased. In preeclampsia, aldosterone is decreased less than rennin. Therefore current studies were undertaken to determine the relationship between aldosterone to renin ratio (ARR) and uterine artery perfusion via RI value.
Materials and Methods
In this study, the relationship between plasma aldosterone and renin concentration was determined in 27 preeclamptic women and 50 normal pregnant women, whose gestational weeks were matched. The aldosterone to renin ratio was calculated and compared between the two groups. Doppler velocimetry of the uterine artery, which was used to calculate resistance index (RI), was performed on all subjects. The relationship between ARR and RI value was reviewed.
In the preeclampsia group, RI value of the uterine artery was significantly higher than that of normal pregnant women. Both plasma renin and aldosterone concentrations were lower in the preeclampsia group. However, the ratio of these two parameters was significantly higher (38.3 vs. 16.1, p < 0.001); the greater ARR, the higher the RI of the uterine artery (r2=0.053, p = 0.048).
This study demonstrates that a high aldosterone to renin ratio may have a negative effect on perfusion of the uterine artery and play an important role in the pathophysiology of preeclampsia.
Preeclampsia; aldosterone; renin; uterine artery
Accumulating evidence supports a potential role for dopamine in the regulation of insulin secretion. We examined the association between circulating dopamine and C-peptide concentrations using data from the Graz Endocrine Causes of Hypertension (GECOH) study.
RESEARCH DESIGN AND METHODS
After 12 h of fasting, we measured plasma dopamine and serum C-peptide levels and established determining factors of insulin secretion in 201 nondiabetic hypertensive patients (mean age 48.1 ± 16.0 years; 61.7% women).
Mean dopamine and C-peptide concentration were 33.4 ± 38.6 pg/mL and 3.1 ± 2.7 ng/mL, respectively. A strong and inverse correlation was observed between dopamine and C-peptide levels (r = −0.423, P < 0.001). There was no significant relationship between C-peptide, plasma epinephrine, and norepinephrine. C-peptide levels decreased steadily and significantly from tertile 1 of dopamine (3.6 ng/mL [95% CI 2.9–4.1]) to tertile 3 (1.6 ng/mL [1.5–2.7], P < 0.001) after multivariate adjustment.
The inverse association between dopamine and C-peptide highlights the need to evaluate whether dopamine could be effective for modulating endocrine pancreatic function.
Idiopathic primary hyperaldosteronism (IHA) and low-renin essential hypertension (LREH) are common forms of hypertension, characterized by an elevated aldosterone-renin ratio (ARR) and hypersensitivity to Angiotensin II (Ang II). They are suggested to be two states within a disease spectrum that progresses from LREH to IHA as the control of aldosterone production by the renin-angiotensin system is weakened. The mechanism(s) that drive this progression remain unknown. Deletion of Twik-related-acid-sensitive K+ channels (TASK) subunits, TASK-1 and TASK-3, in mice (T1T3KO) produces a model of human IHA. Here, we determine the effect of deleting only TASK-3 on the control of aldosterone production and blood pressure. We find that T3KO mice recapitulate key characteristics of human LREH: salt-sensitive hypertension, mild overproduction of aldosterone, decreased plasma renin concentration with elevated ARR, hypersensitivity to endogenous and exogenous Ang II, and failure to suppress aldosterone production with dietary sodium loading. The relative differences in levels of aldosterone output and ARR, and in autonomy of aldosterone production between T1T3KO and T3KO mice are reminiscent of differences in human hypertensive patients with LREH and IHA. Our studies establish a model of LREH and suggest that loss of TASK channel activity may be one mechanism that advances the syndrome of low renin hypertension.
TASK channels; aldosterone; hyperaldosteronism; low renin essential hypertension
Background: Primary aldosteronism is the leading cause of secondary hypertension, the management of this disease requiring an interdisciplinary approach.
Objectives: Evaluation of evolutionary features of patients with secondary hypertension and primary aldosteronism.
Methodology: We have followed 26 patients diagnosed with secondary hypertension and primary aldosteronism, who were admitted consecutively to "C. I. Parhon" Endocrinology Institute between 2004-2009. Of the 26 patients, 17 had adenoma producer of aldosterone (APA), 8 had bilateral adrenal hyperplasia idiopathic (HIA) and one patient had adrenal carcinoma (with hypersecretion of aldosterone). The mean age of the cohort was of 49.3 years (44.9 years for adenomas and 52.6 years for bilateral hyperplasia). The evaluation of the patients included clinical examination, electrocardiogram, Holter BP, echocardiography and determination of plasma aldosterone and renin.
Results: The evolution of the patients with primary aldosteronism was different depending on the anatomoclinic type. In patients with idiopathic bilateral hyperplasia, medical treatment has improved control of hypertension and cardiac and cerebrovascular complications rate was moderate. In patients with unilateral adenoma producing aldosterone, blood pressure had higher values and more frequent complications, but surgical cure of adenomas significantly changed the prognosis of patients. In both cases, the presence of hypokalemia was an additional element of severity.
Conclusions: Regardless of the primary aldosteronism, hypertension was directly involved in cardiac and cerebrovascular complications. Individualization of treatment according to the anatomoclinic type determined a significant improvement of the patients’ prognosis.
secondary hypertension; primary aldosteronism; hypokalemia; surgery
Surgically correctable forms of primary aldosteronism are characterized by unilateral aldosterone hypersecretion and renin suppression, associated with varying degrees of hypertension and hypokalemia. Unilateral aldosterone hypersecretion is caused by an aldosterone-producing adenoma (also known as Conn's adenoma and aldosteronoma), primary unilateral adrenal hyperplasia and rare cases of aldosterone-producing adrenocortical carcinoma. In these forms, unilateral adrenalectomy can cure aldosterone excess and hypokalemia, but not necessarily hypertension. The prevalence of primary aldosteronism in the general population is not known. Its prevalence in referred hypertensive populations is estimated to be between 6 and 13%, of which 1.5 to 5% have an aldosterone-producing adenoma or primary unilateral adrenal hyperplasia. Taking into account referral biases, the prevalence of surgically correctable primary aldosteronism is probably less than 1.5% in the hypertensive population and less than 0.3% in the general adult population. Surgically correctable primary aldosteronism is sought in patients with hypokalemic, severe or resistant forms of hypertension. Recent recommendations suggest screening for primary aldosteronism using the aldosterone to renin ratio. Patients with a raised ratio then undergo confirmatory suppression tests. The differential diagnosis of hypokalemic hypertension with low renin includes mineralocorticoid excess, with the mineralocorticoid being cortisol or 11-deoxycorticosterone, apparent mineralocorticoid excess, pseudo-hypermineralocorticoidism in Liddle syndrome or exposure to glycyrrhizic acid. Once the diagnosis is confirmed, adrenal computed tomography is performed for all patients. If surgery is considered, taking into consideration the clinical context and the desire of the patient, adrenal vein sampling is performed to detect whether or not aldosterone hypersecretion is unilateral. Laparoscopic surgery for unilateral aldosterone hypersecretion is associated with a morbidity of about 8%, with most complications being minor. It generally results in the normalization of aldosterone secretion and kalemia, and in a large decrease in blood pressure, but normotension without treatment is only achieved in half of all cases. Normotension following adrenalectomy is more frequent in young patients with recent hypertension than in patients with long-standing hypertension or a family history of hypertension.
Hypertension is a common disorder that affects a large heterogeneous patient population. Subgroups can be identified on the basis of their responses to hormonal and biologic stimuli. These subgroups include low-renin hypertensives and nonmodulators. Aldosterone, the principal human mineralocorticoid, is increasingly recognized as playing a significant role in cardiovascular morbidity, and its role in hypertension has recently been reevaluated with studies that suggest that increased aldosterone biosynthesis (as defined by an elevated aldosterone to renin ratio) is a key phenotype in up to 15% of individuals with hypertension. It was reported previously that a polymorphism of the gene (C to T conversion at position −344) encoding aldosterone synthase is associated with hypertension, particularly in individuals with a high ratio. However, the most consistent association with this variant is a relative impairment of adrenal 11β-hydroxylation. This review explores the evidence for this and provides a hypothesis linking impaired 11β-hydroxylation and hypertension with a raised aldosterone to renin ratio. It is also speculated that there is substantial overlap between this group of patients and previously identified low-renin hypertensives and nonmodulators. Thus, these groups may form a neurohormonal spectrum reflecting different stages of hypertension or indeed form sequential steps in the natural history of hypertension in genetically susceptible individuals.
To determine the mechanism underlying altered adrenal responsiveness in patients with essential hypertension, the renin-angiotensin-aldosterone axis was assessed in normotensive and hypertensive subjects using three pharmacological probes: SQ 20881, a converting enzyme inhibitor; saralasin, a competitive angiotensin antagonist with prominent agonist properties; and angiotensin itself. All subjects were studied while supine and in balance on a 10 meq Na/100 meq K intake. The decrement in plasma aldosterone with SQ 20881 in 26 hypertensive subjects (15±3 ng/dl) was normal (13±4 ng/dl), suggesting that the altered adrenal responsiveness in hypertensives is not because of a change in a postreceptor event or in the relative contribution of angiotensin to the control of aldosterone secretion.
Saralasin at a dose (0.1 μg/kg per min) that reduced aldosterone levels in all normals produced a normal aldosterone decrement (14±3 ng/dl) in 19 patients with renovascular hypertension (12±4 ng/dl). The same dose, however, had no net effect on plasma aldosterone levels in 70 patients with normal or high renin essential hypertension (−1±1 ng/dl) despite identical metabolic balance and control renin and angiotensin levels. The altered response could be explained by an agonist effect, aldosterone rising in 45 of the essential hypertensives. There were no significant differences between normal and abnormal responders in pre- and postcortisol, -potassium, -renin and -angiotensin concentrations.
Angiotensin was infused (0.1-3 ng/kg per min) in 15 patients with normal renin essential hypertension, previously studied with saralasin. A probit transformation defined the dose required to induce a 50% increase in aldosterone (ED50). In the patients in whom aldosterone rose with saralasin, the dose required to induce a 50% increase was significantly greater (P < 0.001) than in those in whom aldosterone fell normally (1.02±0.06 [SD] vs. 0.38±0.07 ng/kg per min). Vascular responses were similar in the various groups. We conclude that altered adrenal responsiveness to angiotensin in some essential hypertensive patients is secondary to a change in the interaction of angiotensin with its adrenal receptor.
Leucocyte telomere length (LTL) chronicles the cumulative burden of oxidative stress and inflammation over a life course. Activation of the renin-angiotensin-aldosterone system (RAAS) is associated with increased oxidative stress and inflammation. Therefore, LTL may be related to circulating biomarkers of the RAAS.
We evaluated the cross-sectional relations of LTL (dependent variable) to circulating renin and aldosterone concentrations and the renin-aldosterone ratio (all logarithmically-transformed; independent variables) in 1203 Framingham Study participants (mean age 59 years, 51% women). We used multivariable linear regression and adjusted for age, blood pressure, hypertension treatment, smoking, diabetes, body mass index, hormone replacement therapy, serum creatinine and the urine sodium-creatinine ratio.
Overall, multivariable-adjusted LTL was inversely related to renin (beta coefficient per unit increase [β]=-0.038; p= 0.036), directly related to aldosterone (β=0.099; p= 0.002), and inversely related to the renin-aldosterone ratio (β=-0.049; p= 0.003). Relations of LTL to biomarkers were stronger in those with hypertension, although a formal test of interaction was not statistically significant (p=0.20). Individuals with hypertension displayed significant associations of LTL with renin (β=-0.060; p= 0.005), aldosterone (β=0.134; p= 0.002) and renin-aldosterone ratio (β=-0.072; p<0.001). Participants with hypertension who were in the top tertile of the renin-aldosterone ratio had LTL that was 182 base pairs shorter relative to those in the lowest tertile.
In our community-based sample, LTL was shorter in individuals with a higher renin-aldosterone ratio, especially so in participants with hypertension. Additional investigations are warranted to confirm our observations.
Telomere; Renin; Aldosterone; Hypertension; Epidemiology; Association; Salt; Oxidative stress
Low renin hypertension is an important and often underdiagnosed cause of hypertension. It may be associated with high aldosterone levels as in Conn's syndrome or low aldosterone levels as in Liddle syndrome, and syndrome of apparent mineralocorticoid excess, glucocorticoid remediable hypertension etc. Some forms of essential hypertension are also associated with low renin levels. Hypokalemia may be an important finding in low renin hypertension. The aldosterone to renin ratio helps in correct diagnosis. The treatment varies with etiology hence an accurate diagnosis is essential. Aldosterone antagonists play an important role in medical management of some varieties of low renin hypertension.
Aldosterone antagonists; hypertension; hypokalemia; low renin hypertension; monogenic hypertension; renin aldosterone ration
Background. Hypertension is the most common cardiovascular disease worldwide and is a major cause of morbidity and mortality. Studies have suggested that the activity of the renin-angiotensin-aldosterone system play a major role in the target organ damage such as left ventricular hypertrophy occuring in hypertension. We sought to determine the relationship between plasma aldosterone and left ventricular mass in untreated African hypertensives. Methods. We recruited 82 newly diagnosed and untreated hypertensives and 51 normal controls. Measurements obtained included echocardiographic LV mass index, plasma aldosterone and renin. Results. The hypertensive subjects had lower renin levels (21.03[6.974] versus 26.66[7.592] ng.mL−1, P = 0.0013), higher LV mass index (52.56[14.483] versus 42.02[8.315] g.m−2.7P < 0.0001) when compared with the controls. There were no univariate associations between LV mass index and plasma aldosterone (r = 0.0179, P = 0.57) and between LV mass index and plasma renin (r = 0.0887, P = 0.61). In a multivariate model involving LV mass index and age, sex, body mass index (BMI), plasma aldosterone, plasma renin and systolic blood pressure (SBP), only age (P = 0.008), BMI (P = 0.046), and SBP (P = 0.001) were independently associated with the LV mass index. Conclusions. In this group of hypertensive Africans, there is no independent association of plasma aldosterone with LV mass. The height of the blood pressure, the body mass index and the age of the subjects determined the LV mass.
Studies were undertaken to determine if the dissociation of aldosterone and plasma renin activity in low-renin essential hypertension is due to altered adrenal responsiveness to angiotensin II. The responsiveness of the adrenal glands to angiotensin II was determined by infusing graded doses of angiotensin II into normal subjects and into patients with essential hypertension and measuring changes in levels of plasma aldosterone in response to the infusion. To minimize the influence of endogenous angiotensin II and ACTH, supplemental sodium and dexamethasone were given before the infusions. Levels of plasma aldosterone and plasma renin activity were determined in normal subjects and in the same patients after the combined stimuli of furosemide and upright posture, a maneuver used to increase the level of endogenous angiotensin II. To determine if the changes in levels of plasma aldosterone during infusion of angiotensin II were due to alteration of the metabolic clearance of aldosterone, the metabolic clearance of aldosterone was measured before and during the infusion of angiotensin II.
After sodium loading, dexamethasone treatment, and supine posture, levels of plasma aldosterone of normal subjects and patients with essential hypertension were suppressed equally. In response to the infusion of angiotensin II, the levels of plasma aldosterone of patients with low-renin essential hypertension were significantly higher than those of normal subjects or of patients with normal-renin essential hypertension. After furosemide and upright posture, levels of plasma aldosterone of patients with low-renin essential hypertension were significantly higher than those of patients with normal-renin essential hypertension, despite a blunted response in plasma renin activity of the patients with low-renin essential hypertension. Decreases in metabolic clearance of aldosterone during infusion of angiotensin II were similar in patients with normal-renin essential hypertension and in patients with low-renin essential hypertension and accounted for only a small fraction of the marked increase in levels of plasma aldosterone of patients with low-renin essential hypertension. It is concluded that patients with low-renin essential hypertension have increased adrenal sensitivity to angiotensin II. This increased sensitivity may explain the dissociation of aldosterone and plasma renin activity in low-renin essential hypertension.
Primary aldosteronism is the most common cause of secondary hypertension. In the past, screening for primary aldosteronism was offered only in patients with hypertension associated with hypokalemia. Recent studies showed that hypokalemia is seen in only 25% of the patients with primary aldosteronism, which has increased the prevalence of primary aldosteronism to 10–15% of all cases with new onset hypertension.