Active renin versus plasma renin activity to define aldosterone-to-renin ratio for primary aldosteronism

Aldosterone-to-renin ratio (ARR) as a screening tool for primary aldosteronism (PA)

The aldosterone-to-renin ratio (ARR) is the standard screening test for primary aldosteronism (PA). Because of the poor reproducibility of the ARR, repeat testing is recommended if the result is not compatible with the clinical condition. Various methods to measure renin are used in different hospitals in Taiwan, and the ARR cutoff values also differ among laboratories. The Task Force of Taiwan PA recommend using plasma renin activity (PRA) to calculate ARR instead of direct renin concentration (DRC) unless PRA is unavailable, because PRA is widely used in international guidelines and most studies.

Underdiagnosis of Primary Aldosteronism: A Review of Screening and Detection

A clinical condition may be missed due to its higher-than-recognized prevalence or inadequate diagnostic screening. Both factors apply to primary aldosteronism, which is woefully underdiagnosed as a cause of hypertension and end-organ damage. Screening tests should be strongly considered for diseases that pose significant morbidity or mortality if left untreated, that have a high prevalence, and that have treatments that lead to improvement or cure. In this review we present the evidence for each of these points. We outline studies that estimate the prevalence of primary aldosteronism in different at-risk populations and how its recognition has changed over time. We also evaluate myriad studies of screening rates for primary aldosteronism and what factors do and do not influence current screening practices. We discuss the ideal conditions for screening, measuring the aldosterone to renin ratio in different populations that use plasma renin activity or direct renin concentration, and the steps for diagnostic workup of primary aldosteronism. Finally, we conclude with potential strategies to implement higher rates of screening and diagnosis of this common, consequential, and treatable disease.

Comparison of the Chemiluminescence Immunoassay LIAISON® with the Radioimmunoassay for Aldosterone and Renin Measurement

Determination of renin plasma levels is useful in the diagnosis of hypertension and in the therapeutic follow-up of hypertensive patients. Plasmatic concentration of renin decreases in patients with hypertension due to a primary hyperaldosteronism, contrary to renovascular hypertension where concentrations of renin and aldosterone are both elevated. Blood samples (serum, EDTA plasma) were analysed using two different chemiluminiscent methods CLIA LIAISON® and radioimmunoassay for aldosterone (IMMUNOTECH Beckman Coulter) and renin (Cisbio Bioassay) measurements were compared. We used both methods to ascertain the correlation between serum vs. EDTA plasma levels of aldosterone (RIA, CLIA) and renin (IRMA, CLIA) and to compare aldosterone to renin ratios for CLIA and for radioimmunoassay: serum aldosterone to plasma renin and plasma aldosterone to plasma renin. We compared serum aldosterone CLIA vs. RIA (rP=0.933, P<0.001) and plasma renin determined using CLIA vs. IRMA (rP=0.965, P=0.062). Furthermore, we used both methods to establish the correlation between the serum vs. plasma levels of aldosterone: RIA (rP=0.980, P<0.001); CLIA (rP=0.994, P=0.353) and serum vs. plasma levels of renin: IRMA (rP=0.948, P<0.001); CLIA (rP=0.921, P=0.011). Aldosterone (serum, plasma) to plasmatic renin ratios for CLIA (rP=0.999, P=0.286) and for radioimmunoassay (rP=0.992, P=0.025). Our data demonstrate that renin and aldosterone concentrations obtained using CLIA correlate with renin and aldosterone concentrations using radioimmunoassay methods. Correlation coefficients of pair results ranged from 0.921 to 0.994. Aldosterone (serum, EDTA plasma) to plasmatic renin ratios are comparable and any of them can be used with no significant differences found.

Circulating prorenin: its molecular forms and plasma concentrations

The renin-angiotensin-aldosterone system plays pivotal roles in the maintenance of fluid homeostasis and in the pathophysiology of major human diseases. However, the molecular forms of plasma renin/prorenin have not been fully elucidated, and measurements of plasma prorenin levels are still unavailable for clinical practice. We attempted to evaluate the molecular forms of human plasma prorenin and to directly measure its concentration without converting it to renin to determine its activity. Polyacrylamide gel electrophoresis and subsequent immunoblotting using antibodies that specifically recognise prosegment sequences were used to analyse its molecular forms in plasma. We also created a sandwich enzyme-linked immunosorbent assay suitable for directly quantifying the plasma concentration. The plasma level in healthy people was 3.0-13.4 μg/mL, which is from 3 to 4 orders of magnitude higher than the levels reported thus far. Plasma immunoreactive prorenin consists of three major distinct components: a posttranslationally modified full-length protein, an albumin-bound form and a smaller protein truncated at the common C-terminal renin/prorenin portion. In contrast to plasma renin activity, plasma prorenin concentrations were not affected by the postural changes of the donor. Hence, plasma prorenin molecules may be posttranslationally modified/processed or bound to albumin and are present in far higher concentrations than previously thought.

Confounders of the aldosterone-to-renin ratio when used as a screening test in hypertensive patients: A critical analysis of the literature

The aldosterone‐to‐renin ratio (ARR) is a common screening test for primary aldosteronism in hypertensives. However, there are many factors which could confound the ARR test result and reduce the accuracy of this test. The present review's objective is to identify these factors and to describe to what extent they affect the ARR. Our analysis revealed that sex, age, posture, and sodium‐intake influence the ARR, whereas assay techniques do not. Race and body mass index have an uncertain effect on the ARR. We conclude that several factors can affect the ARR. Not taking these factors into account could lead to misinterpretation of the ARR.

Change in kidney function after unilateral adrenalectomy in patients with primary aldosteronism: identification of risk factors for decreased kidney function

PURPOSE

Glomerular filtration rate (GFR) has been reported to decrease after unilateral adrenalectomy in patients with primary aldosteronism (PA). The aim of this study was to identify clinical predictors for decreased GFR after adrenalectomy in patients with PA.

METHODS

The records of 187 patients (98 patients with PA and 89 with non-PA adrenal disease) who were followed up for at least 6 months after unilateral adrenalectomy were retrospectively analyzed. Estimated GFR (eGFR) was investigated at 1, 3, and 6 months postoperatively. Preoperative risk factors for eGFR% decline at 1 month ([preoperative eGFR-eGFR at 1 month]/preoperative eGFR × 100) and postoperative CKD development were investigated.

RESULTS

The eGFR decreased significantly at 1 month and remained stable in the PA group. However, there were no significant changes in eGFR in the non-PA group over the 6-month period. In the PA group, a high preoperative eGFR and high aldosterone to renin ratio (ARR) were independently associated with eGFR% decline at 1 month. In patients with PA but without preoperative CKD (n = 68), a low preoperative eGFR and high ARR were independent risk factors for developing postoperative CKD. The best preoperative cut-off values of eGFR and ARR for predicting the development of postoperative CKD were ≤ 102 ml/min/1.73 m² and ≥ 448 ng/dl:ng/ml/h, respectively.

CONCLUSIONS

Renal function deteriorated significantly after unilateral adrenalectomy in patients with PA. Clinicians must pay attention to postoperative renal function in PA patients at elevated risk of developing decreased kidney function.

Age-Related Cutoffs of Plasma Aldosterone/Renin Concentration for Primary Aldosteronism Screening

AIM

This retrospective study is aimed at investigating whether aldosterone-renin ratio (ARR) cutoffs calculated by the plasma aldosterone concentration (PAC)/plasma renin concentration (PRC) should be set differently in patients of different ages.

METHODS

521 hypertensive patients were screened for primary aldosteronism (PA) by the PAC/PRC. 174 patients diagnosed with PA and 311 patients with essential hypertension (EH) were included in the final analysis. Subjects were subdivided into four age groups: <40, 40-49, 50-59, and ≥60 years old.

RESULTS

The accuracy of the ARR varied greatly among the different age groups. An ARR of 3.7 (ng/dl)/(μIU/ml) had a sensitivity of 100% and a specificity of 80% in patients ≥ 60 years old. With this cutoff, the sensitivities in patients < 40, 40-49, and 50-59 years old were 74%, 82%, and 87%, respectively, and the specificities were 94%, 95%, and 94%, respectively. To achieve a sensitivity higher than 90%, the ARR cutoff needed to be lowered to 2.0 (ng/dl)/(μIU/ml) for patients 40-49 and 50-59 years old, resulting in sensitivities of 90% and 95%, respectively, and specificities of 80% and 84%, respectively. To achieve a sensitivity higher than 90%, the ARR cutoff needed to be lowered to 1.0 (ng/dl)/(μIU/ml) for patients < 40 years old, resulting in a sensitivity of 90% and a specificity of 82%.

CONCLUSIONS

An ARR of 3.7 (ng/dl)/(μIU/ml) is optimal for patients ≥ 60 years; for patients 40-59 years, the optimal ARR cutoff is 2.0; for those younger than 40 years, an ARR of 1.0 may be more reasonable.

Update in diagnosis and management of primary aldosteronism

Primary aldosteronism (PA) is a group of disorders in which aldosterone is excessively produced. These disorders can lead to hypertension, hypokalemia, hypervolemia and metabolic alkalosis. The prevalence of PA ranges from 5% to 12% around the globe, and the most common causes are adrenal adenoma and adrenal hyperplasia. The importance of PA recognition arises from the fact that it can have a remarkably adverse cardiovascular and renal impact, which can even result in death. The aldosterone-to-renin ratio (ARR) is the election test for screening PA, and one of the confirmatory tests, such as oral sodium loading (OSL) or saline infusion test (SIT), is in general necessary to confirm the diagnosis. The distinction between adrenal hyperplasia (AH) or aldosterone-producing adenoma (APA) is essential to select the appropriate treatment. Therefore, in order to identify the subtype of PA, imaging exams such as computed tomography or magnetic ressonance imaging, and/or invasive investigation such as adrenal catheterization must be performed. According to the subtype of PA, optimal treatment – surgical for APA or pharmacological for AH, with drugs like spironolactone and amiloride – must be offered.

Novel Approach to Establishing an Aldosterone: Renin Ratio Cutoff for Primary Aldosteronism

Direct renin concentration is replacing plasma renin activity in many laboratories for the investigation of primary aldosteronism, which may have a significant impact on the resulting aldosterone:renin ratios. We sought to develop a population-based approach to establishing an aldosterone:renin ratio cutoff when transitioning between assays. A population-based study was performed in Calgary, Alberta, Canada of 4301 individuals who received testing from January 2012 to November 2015. In 2014, direct renin concentration replaced plasma renin activity in routine testing. We described the prevalence of primary aldosteronism in our population before the change and, using the assumption of disease prevalence stability, determined the corresponding ratio cutoffs after the introduction of the new assay. During the initial portion of the study (using plasma renin activity), 4.9% of those screened were classified as highly probable cases, whereas 10.4% were considered probable and 28.9% possible using locally validated cutoffs. Aldosterone:renin ratio cutoffs were then determined for the direct renin concentration assay. A highly probable case of primary aldosteronism corresponded to a cutoff of >100 pmol L −1 mIU −1 L −1 with hypokalemia. A probable case corresponded to a cutoff of >100 and a possible case to >35 pmol L −1 mIU −1 L −1 . In contrast, cutoffs derived using a conversion factor resulted in significantly higher cutoffs and the potential for missed cases. In conclusion, using large population data, historically consistent aldosterone:renin ratio cutoffs can be established when transitioning between assays. Population-derived cutoffs may be more appropriate for clinical use and less likely to result in false-negative classification than those obtained from conventional direct method comparisons.

Albumin May Prevent the Morbidity of Paracentesis-Induced Circulatory Dysfunction in Cirrhosis and Refractory Ascites: A Pilot Study

BACKGROUND

Large-volume total paracentesis may result in paracentesis-induced circulatory dysfunction, which is associated with poor outcomes.

AIMS

To explore the short- and long-term effects of paracentesis-induced circulatory dysfunction on systemic hemodynamics, renal function and other cirrhosis-related complications in patients with refractory ascites, following subtotal large-volume paracentesis.

METHODS

Patients with cirrhosis and refractory ascites without renal dysfunction had systemic hemodynamics, renal function, and neurohormones (plasma active renin, aldosterone, norepinephrine and angiotensin II) measured pre- and 6 days post-paracentesis. Paracentesis was limited to ≤8 L with 6-8 g of albumin per liter ascites drained. Patients were followed up until transjugular intrahepatic portosystemic shunt insertion, liver transplantation, or death. Paracentesis-induced circulatory dysfunction was defined as >50 % increase in plasma active renin 6 days post-paracentesis.

RESULTS

Fifty-seven patients (mean age 59.0 ± 9.4 years) had mean 6.8 ± 1.8 L of ascites removed with 9 ± 3 g of albumin given/L of ascites drained. Patients were followed up for 715 ± 104 days. Twenty-three patients (40.4 %) developed paracentesis-induced circulatory dysfunction with unchanged serum creatinine on day six, despite worsening of hemodynamics (mean arterial pressure 90 ± 10 mmHg at baseline vs. 84 ± 8 mmHg on day six, p < 0.05). Similar hemodynamic changes were observed among patients without paracentesis-induced circulatory dysfunction. There was no significant difference in the long-term renal function or cirrhosis-related complications between the groups.

CONCLUSION

The occurrence of paracentesis-induced circulatory dysfunction, as defined by plasma active renin, may not have a significant short- and long-term impact on renal function or cirrhosis-related complications in patients with refractory ascites who undergo subtotal paracentesis with albumin infusion.

Primary Aldosteronism: Changing Definitions and New Concepts of Physiology and Pathophysiology Both Inside and Outside the Kidney

In the 60 years that have passed since the discovery of the mineralocorticoid hormone aldosterone, much has been learned about its synthesis (both adrenal and extra-adrenal), regulation (by renin-angiotensin II, potassium, adrenocorticotrophin, and other factors), and effects (on both epithelial and nonepithelial tissues). Once thought to be rare, primary aldosteronism (PA, in which aldosterone secretion by the adrenal is excessive and autonomous of its principal regulator, angiotensin II) is now known to be the most common specifically treatable and potentially curable form of hypertension, with most patients lacking the clinical feature of hypokalemia, the presence of which was previously considered to be necessary to warrant further efforts towards confirming a diagnosis of PA. This, and the appreciation that aldosterone excess leads to adverse cardiovascular, renal, central nervous, and psychological effects, that are at least partly independent of its effects on blood pressure, have had a profound influence on raising clinical and research interest in PA. Such research on patients with PA has, in turn, furthered knowledge regarding aldosterone synthesis, regulation, and effects. This review summarizes current progress in our understanding of the physiology of aldosterone, and towards defining the causes (including genetic bases), epidemiology, outcomes, and clinical approaches to diagnostic workup (including screening, diagnostic confirmation, and subtype differentiation) and treatment of PA.

SFE/SFHTA/AFCE Consensus on Primary Aldosteronism, part 2: First diagnostic steps

In patients with suspected primary aldosteronism (PA), the first diagnostic step, screening, must have high sensitivity and negative predictive value. The aldosterone-to-renin ratio (ARR) is used because it has higher sensitivity and lower variability than other measures (serum potassium, plasma aldosterone, urinary aldosterone). ARR is calculated from the plasma aldosterone (PA) and plasma renin activity (PRA) or direct plasma renin (DR) values. These measurements must be taken under standard conditions: in the morning, more than 2hours after awakening, in sitting position after 5 to 15minutes, with normal dietary salt intake, normal serum potassium level and without antihypertensive drugs significantly interfering with the renin-angiotensin-aldosterone system. To rule out ARR elevation due to very low renin values, ARR screening is applied only if aldosterone is>240pmol/l (90pg/ml); DR values<5mIU/l are assimilated to 5mIU/l and PRA values<0.2ng/ml/h to 0.2ng/ml/h. We propose threshold ARR values depending on the units used and a conversion factor (pg to mIU) for DR. If ARR exceeds threshold, PA should be suspected and exploration continued. If ARR is below threshold or if plasma aldosterone is<240pmol/l (90pg/ml) on two measurements, diagnosis of PA is excluded.

Association of Post-Saline Load Plasma Aldosterone Levels With Left Ventricular Hypertrophy in Primary Hypertension

BACKGROUND

Left ventricular hypertrophy (LVH) is an independent risk factor for cardiovascular morbidity in hypertension. Current evidence suggests a contribution to LVH of plasma aldosterone levels that are inappropriately elevated for the salt status. The aim of this study was to investigate whether inappropriate modulation of aldosterone production by a saline load is associated with left ventricular (LV) mass in hypertensive patients.

METHODS

In 90 hypertensive patients free of clinically relevant cardiovascular complications in whom secondary forms of hypertension were ruled out, we performed a standard intravenous saline load (0.9% NaCl, 2 l in 4 hours) with measurement of plasma aldosterone and active renin at baseline and end of infusion. Bi-dimensional echocardiography was performed for the assessment of cardiac morphology and function.

RESULTS

LVH was present in 19% of patients who had significantly worse renal function and higher body mass, blood pressure, and plasma aldosterone levels measured both at baseline and after the saline load than patients without LVH. LV mass was directly related to age, body mass, systolic blood pressure, duration of hypertension, baseline, and post-saline load plasma aldosterone levels and inversely to glomerular filtration. Multivariate regression analysis showed independent correlation of LV mass with body mass, systolic blood pressure, and plasma aldosterone levels measured after intravenous saline load, but not at baseline.

CONCLUSIONS

In patients with hypertension, aldosterone levels measured after intravenous saline load are related to LV mass independent of age, body mass, and blood pressure, suggesting that limited ability of salt to modulate aldosterone production could contribute to LVH.

Screening for primary aldosteronism in an argentinian population: a multicenter prospective study

OBJECTIVES

Primary aldosteronism (PA) is characterized by the autonomous overproduction of aldosterone. Its prevalence has increased since the use of the aldosterone (ALD)/plasma renin activity (PRA) ratio (ARR). The objective of this study is to determine ARR and ARC (ALD/plasma renin concentration ratio) cut-off values (COV) and their diagnostic concordance (DC%) in the screening for PA in an Argentinian population.Design multicenter prospective study.

SUBJECTS AND METHODS

We studied 353 subjects (104 controls and 249 hypertensive patients). Serum aldosterone, PRA and ARR were determined. In 220 randomly selected subjects, 160 hypertensive patients and 60 controls, plasma renin concentration (PRC) was simultaneously measured and ARC was determined.

RESULTS

According to the 95th percentile of controls, we determined a COV of 36 for ARR and 2.39 for ARC, with ALD ≥ 15 ng/dL. In 31/249 hypertensive patients, ARR was ≥ 36. PA diagnosis was established in 8/31 patients (23/31 patients did not complete confirmatory tests). DC% between ARR and ARC was calculated. A significant correlation between ARR and ARC (r = 0.742; p < 0.0001) was found only with PRA > 0.3 ng/mL/h and PRC > 5 pg/mL. DC% for ARR and ARC above or below 36 and 2.39 was 79.1%, respectively.

CONCLUSION

This first Argentinian multicenter study determined a COV of 36 for ARR and 2.39 for ARC. Applying an ARR ≥ 36 in the hypertensive group, we confirmed PA in a higher percentage of patients than the previously reported one in our population. As for ARC, further studies are needed for its clinical application, since DC% is acceptable only for medium range renin values.

Use of plasma renin activity to monitor mineralocorticoid treatment in dogs with primary hypoadrenocorticism: desoxycorticosterone versus fludrocortisone

Background

Measurement of plasma renin activity (PRA) is the gold standard for monitoring mineralocorticoid treatment in humans with primary hypoadrenocorticism (PH).

Objectives

To compare PRA in dogs with newly diagnosed PH, dogs with diseases mimicking PH, and healthy dogs, and evaluate measurement of PRA to monitor therapeutic effects in dogs with PH treated with different mineralocorticoids.

Animals

Eleven dogs with newly diagnosed PH (group 1), 10 dogs with diseases mimicking PH (group 2), 21 healthy dogs (group 3), 17 dogs with treated PH (group 4).

Methods

In group 1, PRA was measured before treatment and at different times after initiating treatment. In groups 2 and 3, PRA was measured at initial presentation only. In group 4, no baseline PRA was obtained but PRA was measured once or every 1–6 months during treatment. Mineralocorticoid treatment consisted of fludrocortisone acetate (FC) or desoxycorticosterone pivalate (DOCP).

Results

Plasma renin activity before treatment was increased in dogs with PH compared to normal dogs and dogs with diseases mimicking PH with median activity of 27, 0.8, and 1.0 ng/mL/h, respectively. In dogs with PH, PRA decreased and normalized with mineralocorticoid treatment using DOCP but not with FC. In dogs treated with DOCP, PRA was lower than in dogs treated with FC. Plasma sodium concentrations were higher and potassium concentrations were lower with DOCP treatment compared to FC treatment.

Conclusion and Clinical Importance

Plasma renin activity is a reliable tool for monitoring mineralocorticoid treatment. DOCP treatment more effectively suppresses PRA compared to FC in dogs with PH.

Pathophysiology, diagnosis, and treatment of mineralocorticoid disorders

The renin-angiotensin-aldosterone system (RAAS) is a major regulator of blood pressure control, fluid, and electrolyte balance in humans. Chronic activation of mineralocorticoid production leads to dysregulation of the cardiovascular system and to hypertension. The key mineralocorticoid is aldosterone. Hyperaldosteronism causes sodium and fluid retention in the kidney. Combined with the actions of angiotensin II, chronic elevation in aldosterone leads to detrimental effects in the vasculature, heart, and brain. The adverse effects of excess aldosterone are heavily dependent on increased dietary salt intake as has been demonstrated in animal models and in humans. Hypertension develops due to complex genetic influences combined with environmental factors. In the last two decades, primary aldosteronism has been found to occur in 5% to 13% of subjects with hypertension. In addition, patients with hyperaldosteronism have more end organ manifestations such as left ventricular hypertrophy and have significant cardiovascular complications including higher rates of heart failure and atrial fibrillation compared to similarly matched patients with essential hypertension. The pathophysiology, diagnosis, and treatment of primary aldosteronism will be extensively reviewed. There are many pitfalls in the diagnosis and confirmation of the disorder that will be discussed. Other rare forms of hyper- and hypo-aldosteronism and unusual disorders of hypertension will also be reviewed in this article.

The ratios of aldosterone / plasma renin activity (ARR) versus aldosterone / direct renin concentration (ADRR)

Primary aldosteronism (PA) is estimated to occur in 5-12% of patients with hypertension. Assessment of aldosterone / plasma renin activity (PRA) ratio (ARR) has been used as a screening test in patients suspected of PA. Direct determination of renin (DRC) and calculation of aldosterone / direct renin concentration ratio (ADRR) could be similarly useful for screening patients suspected of PA. The study included 62 patients with indication for evaluation of the renin-angiotensin-aldosterone system and 35 healthy volunteers. In all participants we measured concentrations of serum aldosterone, plasma direct renin, and PRA after a night's rest and again after walking for two hours. The concentrations of aldosterone, direct renin, and PRA were measured by isotopic methods (radioimmunoassay (RIA) / immunoradiometric assay (IRMA)). Correlations of ARR with ADRR in the supine position were r = 0.9162, r(2) = 0.8165 (p < 0.01); and in the up-right position were r = 0.7765, r(2) = 0.9153 (p < 0.01). The cut-off values of ARR and ADRR ≥ 100 presented highest specificity (99%) for the diagnosis of PA; however, quite acceptable specificity and sensitivity (> 80% and 100%, respectively) appeared for the ratios ≥ 30. We suggest that for practical and economic reasons ARR can be replaced by ADRR.

Adrenocortical function in hypotensive patients with end stage renal disease

BACKGROUND

Sustained hypotension among patients with end stage renal disease on dialysis (ESRDh) varies from 5.0% to 12.0%. Despite their role in the regulation of blood pressure (BP) corticoadrenal hormones have been poorly investigated.

OBJECTIVES

This study aims to detect adrenal insufficiency in ESRDh and follow their clinical outcome.

METHODS

Fifty ESRDh and 30 healthy volunteers were studied. In all cases basal blood and saliva were obtained. Synthetic ACTH (25μg) was injected intramuscularly and at 30min saliva was collected. Circulating ACTH, renin, cortisol and aldosterone were measured and steroids were also assessed in saliva by immunoassay.

RESULTS

Fifteen ESRDh achieved steroid responses not different than healthy volunteers; four had primary adrenal insufficiency; six had secondary adrenal insufficiency; nine had selective hypoaldosteronism and sixteen secondary hyperaldosteronism. The years on dialysis did not differ among subgroups. ROC analysis defined the following cut-offs for basal cortisol to predict adrenal insufficiency: in serum ⩽232.0nM (sensitivity (S) 100.0% and specificity (E) 90.0%); in saliva ⩽4.4nM (100.0% S and E). Basal aldosterone cut-off values to predict hyperaldosteronism were: in serum >500.0pM and saliva >60.0pM (100.0% S and E, for both). For the prediction of hypoaldosteronism the basal serum aldosterone was ⩽260.0pM (100% S; 53% E) and in saliva it was ⩽20.1pM (100% S; 58.5% E). Three patients with primary adrenal insufficiency and six with secondary adrenal insufficiency improved general clinical condition and normalized BP on steroids. One patient died before initiation of steroid therapy.

CONCLUSION

Adrenal function should be assessed in ESRDh in order to unmask adrenal insufficient states.

Development and evaluation of an immuno-MALDI (iMALDI) assay for angiotensin I and the diagnosis of secondary hypertension

Plasma renin activity (PRA) is an essential analytical tool for screening and diagnosis of secondary forms of hypertension. Typically, PRA is measured by competitive radioimmunoassay, but there are significant drawbacks to this technique including non-specificity, long analysis times, narrow calibration range, and the requirement for radionucleotides. In this paper, we report a method for plasma renin activity determination by immuno-MALDI mass spectrometry detection. This method overcomes the issues of non-specificity and long analytical times present with RIA, and does not require the use of radionucleotides. As an initial methodological evaluation, plasma renin activity results obtained by radioimmunoassay, LC/ESI-MS/MS, and immuno-MALDI on 64 samples from an outpatient primary aldosteronism screening program have been compared. A strong correlation was found between immuno-MALDI and radioimmunoassay (R2 = 0.9412, 62/64 within the 95% CI of the Bland-Altman plot), and iMALDI and LC/ESI-MS/MS (R2 = 0.9471, 62/64 within the 95% CI of the Bland-Altman plot). Technical replicates showed a 4.8% CV, while inter- and intra-day replicates showed CVs of 17.3% and 17.2% respectively. We have developed an assay capable of measuring PRA without the use of radionucleotides. This immuno-MALDI approach affords the specificity of MS while avoiding the long analytical run times and technical problems associated with HPLC. With the use of robotic sample preparation to optimize precision, this assay should be adaptable to clinical environments.

Diagnosis and management of primary aldosteronism: an updated review

Primary aldosteronism (PA) is the most common secondary form of arterial hypertension, with a particularly high prevalence among patients with resistant hypertension. Aldosterone has been found to be associated with cardiovascular toxicity. Prolonged aldosteronism leads to higher incidence of cardiac events, glomerular hyperfiltration, and potentially bone/metabolic sequels. The wider application of aldosterone/renin ratio as screening test has substantially contributed to increasing diagnosis of PA. Diagnosis of PA consists of two phases: screening and confirmatory testing. Adrenal imaging is often inaccurate for differentiation between an adenoma and hyperplasia, and adrenal venous sampling is essential for selecting the appropriate treatment modality. The etiologies of PA have two main subtypes: unilateral (aldosterone-producing adenoma) and bilateral (micro- or macronodular hyperplasia). Aldosterone-producing adenoma is typically managed with unilateral adrenalectomy, while bilateral adrenal hyperplasia is amenable to pharmacological approaches using mineralocorticoid antagonists. Short-term treatment outcome following surgery is determined by factors such as preoperative blood pressure level and hypertension duration, but evidence regarding long-term treatment outcome is still lacking. However, directed treatments comprising of unilateral adrenalectomy or mineralocorticoid antagonists still potentially reduce the toxicities of aldosterone. Utilizing a physician-centered approach, we intend to provide up-dated information on the etiology, diagnosis, and the management of PA.

Female sex hormones are associated with the reduction of serum sodium and hypertension complications in patients with aldosterone-producing adenoma

This study was conducted to evaluate gender-related differences in clinical characteristics and vascular complications in patients with aldosterone-producing adenomas (APA). Clinical characteristics, biochemical markers and incidence of vascular complications were compared by gender in 187 consecutive patients with APA confirmed by pathological diagnosis. Patients were separated into two groups based on ages either older or younger than 49 years, the average age of menopause among Chinese women (<49 y and ≥49 y). Males had significantly higher BMI than females in the age group of <49 years (p = 0.017). In the <49 years group, males had significantly higher serum sodium levels (p = 0.003). However, no such gender differences in clinical characteristics were observed in patients ≥49 years. A higher proportion of vascular complications was observed in males as compared to females aged <49 years but the difference was not statistically significant (51.4% vs. 34.8%, p = 0.105). The only gender difference observed in vascular complications between patients aged ≥49 years was that a significantly greater proportion of males had cerebrovascular complication compared to females (p = 0.006). Our data suggest that female sex hormones are implicated in reducing serum sodium concentration and vascular complications in female APA patients.

High prevalence of autonomous aldosterone secretion among patients with essential hypertension

BACKGROUND

Previous studies based on standard endocrine testing have generally shown a low prevalence of primary aldosteronism, a form of autonomous aldosterone secretion (AAS), in hypertensive individuals. The purpose of this case-control study was to evaluate whether use of appropriately defined controls and combined testing reveal previously undetected AAS in hypertensives.

MATERIALS AND METHODS

We investigated aldosterone secretion in 180 hypertensives with (n = 44) and without (n = 136) adrenal adenomas on computerized tomography (CT) and 72 matched nonhypertensive individuals with normal adrenal CT. Serum aldosterone and active renin were measured, and the aldosterone/active renin ratio was calculated before and after a modified fludrocortisone-suppression test (FST). In the latter, to eliminate any stimulatory effect of endogenous stress-induced adrenocorticotrophin hormone on aldosterone secretion, we administered 1 mg of dexamethasone on the last day of the classical FST fludrocortisone/dexamethasone suppression test (FDST).

RESULTS

Using the 97·5 percentiles of serum aldosterone (74 pM L(-1)) and the aldosterone/renin ratio (32 pM L(-1) mU(-1) L(-1)) values obtained from the controls following the FDST, normal cut-off values indicative of adequate aldosterone suppression were established. Using the combination of these cut-offs, the estimated prevalence of AAS in patients with hypertension was 31%. Multiple linear regression analysis revealed a significant correlation between systolic and/or diastolic arterial blood pressure and the aldosterone value (P < 0·0001 and P < 0·01, respectively) and/or the aldosterone/renin ratio (P < 0·0001 and P < 0·01, respectively), which were obtained following the FDST.

CONCLUSIONS

By applying new cut-offs obtained following modification of standard testing, AAS is quite prevalent in hypertensive individuals and correlates highly with arterial blood pressure. This may have relevance for both the aetiology of the hypertension and its optimal therapy.

Active renin mass concentration to determine aldosterone-to-renin ratio in screening for primary aldosteronism

Background:

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.

Methods:

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.

Results:

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.

Conclusion:

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.

Aldosterone-to-renin ratio and the relationship between urinary salt excretion and blood pressure in a community of African ancestry

BACKGROUND

Although aldosterone influences the effect of salt intake on blood pressure (BP), the extent to which this occurs at a population level is uncertain. We therefore aimed to determine, at a community level in a group of African descent, whether in the absence of primary aldosteronism, the relationship between salt intake and BP is modified by circulating aldosterone, and the extent to which this occurs.

METHODS

In 575 participants of African ancestry (age >16 years), we assessed whether aldosterone-to-renin ratio (ARR) is associated with the relationship between urinary sodium (Na(+))-to-potassium (K(+)) ratio (urinary Na(+)/K(+)) (from 24-h urine samples), an index of salt intake, and BP.

RESULTS

With adjustments for confounders, interactions between ARR and urinary Na(+)/K(+) were independently associated with systolic BP (SBP) (P < 0.0001), an effect that was accounted for by interactions between serum aldosterone concentrations and urinary Na(+)/K(+) (P < 0.0001), but not between plasma renin concentrations and urinary Na(+)/K(+) (P = 0.52). The interaction between ARR and urinary Na(+)/K(+) translated into a marked difference in the relationship between urinary Na(+)/K(+) and SBP in participants above compared to below the median for ARR (effect of 1 s.d. increase in urinary Na(+)/K(+) on SBP: ARR > median = 4.2 ± 0.6 mm Hg; ARR < median = 1.2 ± 0.4 mm Hg, P < 0.0001). In addition, participants with urinary Na(+)/K(+) above the median had higher multivariate-adjusted SBP (P < 0.001) only if ARR was also above the median.

CONCLUSIONS

In groups of African descent, in the absence of primary aldosteronism, an increased aldosterone concentration relative to renin modifies a substantial proportion of the relationship between urinary Na(+)/K(+) and BP at a community level.

Progress in primary aldosteronism: present challenges and perspectives

Primary Aldosteronism (PA) is a disorder of the adrenal zona glomerulosa (ZG) in which aldosterone secretion is increased and is relatively autonomous of normal regulatory mechanisms. A recent conference in Munich organized by Prof. Reincke addressed advances and challenges related to the screening, diagnosis, and identification of uni- and bilateral involvement of the diseased adrenal of PA. Some infrequently addressed issues are described herein. We postulate that most cases of PA are due to the activation by unknown mechanisms of subset of cells resulting in the formation of a multiple foci or nodules of hyperactive zona glomerulosa cells. This implies that one or several yet unidentified stimuli can drive aldosterone overproduction, as well as the proliferation of aldosterone-producing cells. Current diagnostic procedures allow to determine whether inappropriate aldosterone production is driven by one or both adrenal glands and thus to establish optimal treatment.

High prevalence of autonomous cortisol and aldosterone secretion from adrenal adenomas

OBJECTIVES

Previous studies based on standard endocrine testing have shown a variable incidence of autonomous cortisol secretion (ACS) or autonomous aldosterone secretion (AAS) in patients with single adrenal adenomas (SAA). We tested whether the use of appropriate controls and modification of standard testing, aiming at eliminating interference from endogenous ACTH, reveals previously undetected subtle ACS and AAS by SAA.

DESIGN

Case control study. Patients We investigated 151 patients with SAA and 72 matched controls with normal adrenal computerized tomography.

MEASUREMENTS

All participants had arterial blood pressure recorded, and serum cortisol and aldosterone measured before and after intravenous administration of 250 mug of ACTH, and following dexamethasone administration. Eighty-three patients and all the controls had serum aldosterone and renin measured before and after saline infusion, and after a second saline infusion following dexamethasone administration.

RESULTS

Using the mean + 2 SD values obtained from controls after dexamethasone administration and saline infusion following dexamethasone administration, normal cut-off values for cortisol (30.11 nM), aldosterone (67.59 pM), and aldosterone/renin ratio (9.74 pM/mU/l) were developed. Using these cut-off values, the estimated incidence of ACS and AAS in patients with SAA was 56.63% and 24.10%, respectively, whereas 12.05% had autonomous secretion of both cortisol and aldosterone. Systolic and diastolic arterial blood pressure correlated significantly with the aldosterone/renin ratio following AlphaCTH stimulation (P < 0.0002 and P < 0.001, respectively), and after saline infusion following dexamethasone administration (P < 0.003 and P < 0.002, respectively).

CONCLUSIONS

By applying new cut-offs, ACS and AAS in patients with a SAA is very common, and aldosterone secretion correlates with arterial blood pressure.

Role of unilateral adrenalectomy in bilateral primary aldosteronism: a 22-year single center experience

OBJECTIVE

The aim of the study was to examine blood pressure and biochemical responses to unilateral adrenalectomy in patients with bilateral primary aldosteronism (PA) and identify predictive parameters.

CONTEXT

PA considered due to bilateral autonomous production of aldosterone is usually treated medically. Unilateral adrenalectomy has been considered ineffective. Because quality outcome data are lacking and medical treatment may cause adverse effects or fail to control hypertension, defining the role for unilateral adrenalectomy in bilateral PA is an important clinical issue.

DESIGN AND SETTING

Between 1984 and 2004, 51 of 684 patients diagnosed with bilateral PA underwent unilateral adrenalectomy. This report is based on the records of the 40 considered suitable for inclusion, who were followed for at least 12 (median, 56.4) months.

RESULTS

Hypertension was cured in 15% of patients and improved in 20%, usually within 1 yr of unilateral adrenalectomy. The proportion with controlled hypertension was significantly (P < 0.001) higher after adrenalectomy (65%) than before (25%). Mean systolic (P < 0.001) and diastolic (P < 0.001) blood pressure, left ventricular mass index (P < 0.05), plasma upright aldosterone (P < 0.05), and aldosterone/renin ratio (P < 0.001) fell. Serum creatinine independently predicted hypertension cure.

CONCLUSION

Although this retrospective analysis of patients from a single center does not permit prediction of response rates among patients diagnosed elsewhere, it suggests that unilateral adrenalectomy can be beneficial in some patients with apparent bilateral PA and should not be dismissed as a treatment option.

Activity Assays and Immunoassays for Plasma Renin and Prorenin: Information Provided and Precautions Necessary for Accurate Measurement

Background: Measurement of plasma renin is important for the clinical assessment of hypertensive patients. The most common methods for measuring plasma renin are the plasma renin activity (PRA) assay and the renin immunoassay. The clinical application of renin inhibitor therapy has thrown into focus the differences in information provided by activity assays and immunoassays for renin and prorenin measurement and has drawn attention to the need for precautions to ensure their accurate measurement.

Content: Renin activity assays and immunoassays provide related but different information. Whereas activity assays measure only active renin, immunoassays measure both active and inhibited renin. Particular care must be taken in the collection and processing of blood samples and in the performance of these assays to avoid errors in renin measurement. Both activity assays and immunoassays are susceptible to renin overestimation due to prorenin activation. In addition, activity assays performed with peptidase inhibitors may overestimate the degree of inhibition of PRA by renin inhibitor therapy. Moreover, immunoassays may overestimate the reactive increase in plasma renin concentration in response to renin inhibitor therapy, owing to the inhibitor promoting conversion of prorenin to an open conformation that is recognized by renin immunoassays.

Conclusions: The successful application of renin assays to patient care requires that the clinician and the clinical chemist understand the information provided by these assays and of the precautions necessary to ensure their accuracy.

Intrarenal hemodynamics in primary aldosteronism before and after treatment

CONTEXT

Elevated urinary albumin excretion has been reported in primary aldosteronism and might partially reflect reversible abnormalities initiated by glomerular hyperfiltration.

OBJECTIVE

The aim of the study was to examine the outcome of renal function and intrarenal Doppler velocimetric indices in primary aldosteronism.

DESIGN

We conducted a prospective study of patients with primary aldosteronism who were reevaluated 1 yr after either adrenalectomy or treatment with spironolactone.

SETTING

The study was conducted at a university referral center.

PATIENTS

Fifty-four patients with tumoral or idiopathic aldosteronism were followed after either surgical (n = 24) or medical (n = 30) treatment. Patients with primary aldosteronism were compared with 100 patients with primary hypertension and comparable severity and duration of disease.

MAIN OUTCOME MEASURES

Changes in renal function and intrarenal echo-Doppler indices were measured.

RESULTS

Patients with primary aldosteronism had greater creatinine clearance and urinary albumin excretion than patients with primary hypertension. Patients with primary aldosteronism and creatinine clearance above the median (105 ml/min per 1.73 m(2)) had significantly lower resistance and pulsatility index than patients with creatinine clearance below the median, independent of disease subtype. After 1 yr, creatinine clearance and albuminuria declined, and resistance and pulsatility index increased to the same extent in patients with primary aldosteronism treated with either adrenalectomy or spironolactone. Changes in glomerular filtration and albuminuria were inversely related with baseline values of the resistance index. In primary hypertension, echo-Doppler velocimetric indices did not change during follow-up.

CONCLUSIONS

In primary aldosteronism, sonographic evidence of decreased intrarenal vascular resistance is associated with glomerular hyperfiltration. Both adrenalectomy and spironolactone revert the intrarenal hemodynamic pattern and decrease urinary protein losses.

Clinical Use of Laboratory Tests for the Identification of Secondary Forms of Arterial Hypertension

The prevalence of secondary hypertension can be underestimated if appropriate tests are not performed. The importance of selecting patients with a high pre-test probability of secondary forms of hypertension is first discussed. The laboratory tests currently used for seeking a cause of hypertension are critically reviewed, with emphasis on their operative features and limitations. Strategies to identify primary aldosteronism, the most frequent form of secondary hypertension, and to determine its unilateral or bilateral causes are described. Treatment entails adrenalectomy in unilateral forms, and mineralocorticoid receptor blockade in bilateral forms. Renovascular hypertension is also a common, curable form of hypertension, that should be identified as early as possible to avoid the onset of cardiovascular target organ damage. The tests for its confirmation or exclusion are discussed. The various tests available for the diagnosis of pheochromocytoma, which is much rarer than the above but extremely important to identify, are also described, with emphasis on recent developments in genetic testing. Finally, the tests for diagnosing some rarer monogenic forms and other renal and endocrine causes of arterial hypertension are explored.

Urinary aldosterone-to-active-renin ratio: a useful tool for predicting resolution of hypertension after adrenalectomy in patients with aldosterone-producing adenomas

BACKGROUND

The purpose of this study was to determine the preoperative clinical and biological factors that predict the clinical outcomes after surgery, in subjects with aldosterone-producing adenomas (APAs).

METHODS

Fifty-eight patients (mean age 52 +/- 11 years) with APA were followed up for 43 +/- 13 months after they had undergone unilateral adrenalectomy. The subjects were classified as "cured" (n = 23) if the blood pressure (BP) was <140/90 mm Hg without postoperative medication, "normalized" (n = 20) if BP was <140/90 mm Hg with antihypertensive therapy, and "uncontrolled" (n = 15) if a BP of < or =140/90 mm Hg was not achieved despite intensive therapy.

RESULTS

The cured patients had a significantly lower mean preoperative age, cardiac mass, and serum creatinine (P < 0.001) than the other subjects. The main independent predictors of surgical curability were: age (P < 0.01), low serum potassium (P < 0.0001), and the urinary aldosterone-to-active-renin (UAAR) ratio (P < 0.008). Among the hormonal parameters, the UAAR ratio provided the best area under the receiver operating-characteristics curve (0.802 (confidence interval (CI) 95%: 0.676-0.944)). For a cutoff value of 15, the positive and negative predictive values of the UAAR ratio were 85 and 92%, respectively. In the study population as a whole, surgical treatment restored the age-systolic BP (SBP) relationship (P < 0.006), which was insignificant before surgery.

CONCLUSIONS

Although all the subjects showed lowering of BP after surgery, and the age-BP relationship was restored, the long-term cure rate of APA subjects was 40%. The UAAR ratio, by comparison with other classical hormonal features of primary aldosteronism, was the best independent predictor of the cure of hypertension after adrenalectomy.

Association of leukocyte telomere length with circulating biomarkers of the renin-angiotensin-aldosterone system: the Framingham Heart Study

BACKGROUND

Leukocyte telomere length (LTL) chronicles the cumulative burden of oxidative stress and inflammation over a life course. Activation of the renin-angiotensin-aldosterone system is associated with increased oxidative stress and inflammation. Therefore, LTL may be related to circulating biomarkers of the renin-angiotensin-aldosterone system.

METHODS AND RESULTS

We evaluated the cross-sectional relations of LTL (dependent variable) to circulating renin and aldosterone concentrations and the renin-to-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 mellitus, body mass index, hormone replacement therapy, serum creatinine, and the urine sodium-to-creatinine ratio. Overall, multivariable-adjusted LTL was inversely related to renin (beta coefficient per unit increase, -0.038; P=0.036), directly related to aldosterone (beta=0.099; P=0.002), and inversely related to the renin-to-aldosterone ratio (beta=-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 (beta=-0.060; P=0.005), aldosterone (beta=0.134; P=0.002), and renin-to-aldosterone ratio (beta=-0.072; P<0.001). Participants with hypertension who were in the top tertile of the renin-to-aldosterone ratio had LTL that was 182 base pairs shorter relative to those in the lowest tertile.

CONCLUSIONS

In our community-based sample, LTL was shorter in individuals with a higher renin-to-aldosterone ratio, especially in participants with hypertension. Additional investigations are warranted to confirm our observations.

Screening and diagnosis of primary aldosteronism

Primary aldosteronism (PA) is the most common cause of mineralocorticoid hypertension. Different studies using the plasma aldosterone concentration (PAC)-plasma renin activity ratio (ARR ratio) for the screening of patients with hypertension, have shown a marked increase in the detection rate of PA. PA is commonly caused by an adrenal adenoma (APA) or idiopathic bilateral adrenal hyperplasia of the adrenal zona glomerulosa (IHA) and, in rare cases, by the inherited condition of glucocorticoid-remediable aldosteronism (GRA). The early diagnosis of PA is important, not only because the forms caused by adrenal adenoma are surgically curable, but also because correlation between the duration of PA and the development of cardiovascular complications has been reported. Patients with resistant and/or severe hypertension, patients with hypokalemia, those with a family history of hypertension and stroke at an early age, or patients with an adrenal incidentaloma should be screened for PA using the ARR ratio. Suspicion of PA owing to a pathological ratio requires confirmatory testing, including fludrocortisone suppression test, saline infusion and captopril challenge. Adrenal gland imaging is important in subtype differentiation (APA vs IHA), but adrenal venous sampling is the gold standard and should be used when other tests prove inconclusive. Genetic testing has facilitated detection of GRA.

Long-term cardiac effects of adrenalectomy or mineralocorticoid antagonists in patients with primary aldosteronism

Exposure to excess aldosterone results in cardiac damage in hypertensive states. We evaluated the long-term cardiac structural and functional evolution in patients with primary aldosteronism after surgical or medical treatment. Fifty-four patients with primary aldosteronism were enrolled in a prospective study and were followed for a mean of 6.4 years after treatment with adrenalectomy (n=24) or spironolactone (n=30). At baseline, echocardiographic measurements of patients with primary aldosteronism were compared with those of 274 patients with essential hypertension. Patients with primary aldosteronism had greater left ventricular mass, more prevalent left ventricular hypertrophy, lower early:late-wave diastolic filling velocities ratio, and longer deceleration time than patients with essential hypertension but no differences in relative wall thickness and systolic function. During follow-up, average blood pressure was 135/82 and 137/82 mm Hg in patients treated with adrenalectomy and spironolactone, respectively. In the initial 1-year period, left ventricular mass decreased significantly only in adrenalectomized patients. Subsequent changes in left ventricular mass were greater in patients treated with spironolactone, with an overall change from baseline to the end of follow-up that was comparable in the 2 groups. Prevalence of hypertrophy decreased in both treatment groups, whereas diastolic parameters had only mild and nonsignificant improvement. Changes in blood pressure and pretreatment plasma aldosterone were independent predictors of left ventricular mass decrease in both treatment groups. Thus, in the long-term, both adrenalectomy and spironolactone are effective in reducing left ventricular mass in patients with primary aldosteronism, with effects that are partially independent of blood pressure changes.

Primary aldosteronism: renaissance of a syndrome

Great strides have been made in our understanding of the pathophysiology of primary aldosteronism syndrome since Conn's description of the clinical presentation of a patient with an aldosterone-producing adenoma (APA) more than 50 years ago. It is now recognized that the APA is just one of the seven subtypes of primary aldosteronism. APA and bilateral idiopathic hyperaldosteronism (IHA) are the most common subtypes of primary aldosteronism. Although most clinicians had thought primary aldosteronism to be a rare form of hypertension for more than three decades, it is now recognized to be the most common form of secondary hypertension. Using the plasma aldosterone to plasma renin activity ratio as a case-finding test, followed by aldosterone suppression confirmatory testing, has resulted in much higher prevalence estimates of 5-13% of all patients with hypertension. In addition, there has been a new recognition of the aldosterone-specific cardiovascular morbidity and mortality associated with aldosterone excess. Although thought to be daunting and complex in the past, the diagnostic approach to primary aldosteronism is straightforward and can be considered in three phases: case-finding tests, confirmatory tests and subtype evaluation tests. Patients with hypertension and hypokalaemia (regardless of presumed cause), treatment-resistant hypertension (three antihypertensive drugs and poor control), severe hypertension (>or= 160 mmHg systolic or >or= 100 mmHg diastolic), hypertension and an incidental adrenal mass, onset of hypertension at a young age or patients being evaluated for other forms of secondary hypertension should undergo screening for primary aldosteronism. In patients with suspected primary aldosteronism, screening can be accomplished by measuring a morning (preferably between 0800 and 1000 h) ambulatory paired random plasma aldosterone concentration (PAC) and plasma renin activity (PRA). An increased PAC:PRA ratio is not diagnostic by itself, and primary aldosteronism must be confirmed by demonstrating inappropriate aldosterone secretion. Aldosterone suppression testing can be performed with orally administered sodium chloride and measurement of urinary aldosterone or with intravenous sodium chloride loading and measurement of PAC. Unilateral adrenalectomy in patients with APA or unilateral adrenal hyperplasia results in normalization of hypokalaemia in all these patients; hypertension is improved in all and is cured in approximately 30-60% of them. In bilateral adrenal forms of primary aldosteronism, unilateral or bilateral adrenalectomy seldom corrects the hypertension and they should be treated medically with a mineralocorticoid receptor antagonist.

Relationships of plasma renin levels with renal function in patients with primary aldosteronism

BACKGROUND

The renal damage that is present in primary aldosteronism might reflect functional and potentially reversible abnormalities that are initiated by glomerular hyperfiltration. The aim of this study was to investigate the relationships of plasma renin and aldosterone concentrations with renal outcomes after treatment of primary aldosteronism.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Fifty-six consecutive patients who had primary aldosteronism and were recruited in a university center were studied. Patients were prospectively followed after either surgical or medical treatment for a mean of 6.2 yr, during which they received antihypertensive drugs to reach a target BP of <140/90 mmHg.

RESULTS

At baseline, patients with primary aldosteronism had higher creatinine clearance and albuminuria than 323 patients with essential hypertension and 113 normotensive individuals. In patients with primary aldosteronism, plasma active renin levels that were higher than the lower limit of detection (2.5 pg/ml) were associated with higher BP, plasma potassium, and albuminuria and lower creatinine clearance. Plasma aldosterone concentrations that were higher than the median value (225 pg/ml) were associated with lower plasma potassium and higher creatinine clearance. Creatinine clearance was correlated directly with plasma aldosterone and inversely with renin. During follow-up, patients with higher baseline plasma renin required use of more antihypertensive drugs to obtain BP control and had a smaller early decline in albuminuria than did patients with suppressed renin.

CONCLUSIONS

Escape of renin from suppression by excess aldosterone is associated with evidence of more severe renal damage in patients with primary aldosteronism and predicts less favorable outcomes after treatment.

[Primary aldosteronism caused by aldosteronoma: problems in the etiologic diagnosis]

Primary aldosteronism (PA) represents an important cause of secondary hypertension, potentially curable, and it has been receiving particular attention due to its increasing prevalence, after the beginning of the use of plasma aldosterone concentration to plasma renin activity ratio as a screening method. We present a case of PA caused by an aldosteronoma associated with a contralateral nonfunctioning adrenal adenoma, which resulted in difficulties in the final diagnosis. We discuss the most appropriated tests to screen, confirm the diagnosis of PA and define the etiology of the disorder, especially the adrenal veins sampling to distinguish the aldosteronoma and idiopathic hyperaldosteronism and to guide successful treatment.