Diagnosis under random conditions of all disorders of the renin-angiotensin-aldosterone axis, including primary hyperaldosteronism

Shifting paradigms in primary aldosteronism: reconsideration of screening strategy via integrating pathophysiological insights

Several decades have passed since the description of the first patient with primary aldosteronism (PA). PA was initially classified in two main forms: aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA). However, the pathogenesis of PA has now been shown to be far more complex. For this reason, the traditional classification needs to be updated. Given the recent advancements in our understanding of PA pathogenesis, we should reevaluate how frequent PA cases are, beginning with the reconstruction of the screening strategy. Recent studies consistently indicated that PA has been identified in 22% of patients with resistant hypertension and 11% even in normotensives. The frequency is influenced by the screening strategy and should be based on understanding the pathogenesis of PA. Progress has been made to promote our understanding of the pathogenesis of PA by the findings of aldosterone driver mutations, which have been found in normotensives and hypertensives. In addition, much clinical evidence has been accumulated to indicate that there is a spectrum in PA pathogenesis. In this review, we will summarize the recent progress in aldosterone measurement methods based on LC-MS/MS and the current screening strategy. Then, we will discuss the progress of our understanding of PA, focusing on aldosterone driver mutations and the natural history of PA. Finally, we will discuss the optimal strategy to improve screening rate and case detection.

Screening for Primary Aldosteronism by Mass Spectrometry Versus Immunoassay Measurements of Aldosterone: A Prospective Within-Patient Study

BACKGROUND

Measurements of aldosterone by mass spectrometry are more accurate and less prone to interferences than immunoassay measurements, and may produce a more accurate aldosterone:renin ratio (ARR) when screening for primary aldosteronism (PA).

METHODS

Differences in diagnostic performance of the ARR using mass spectrometry vs immunoassay measurements of aldosterone were examined in 710 patients screened for PA. PA was confirmed in 153 patients and excluded in 451 others. Disease classifications were not achieved in 106 patients. Areas under receiver-operating characteristic curves (AUROC) and other measures were used to compare diagnostic performance.

RESULTS

Mass spectrometry-based measurements yielded lower plasma aldosterone concentrations than immunoassay measurements. For the ARR based on immunoassay measurements of aldosterone, AUROCs were slightly lower (P = 0.018) than those using mass spectrometry measurements (0.895 vs 0.906). The cutoff for the ARR to reach a sensitivity of 95% was 30 and 21.5 pmol/mU by respective immunoassay and mass spectrometry-based measurements, which corresponded to specificities of 57% for both. With data restricted to patients with unilateral PA, diagnostic sensitivities of 94% with specificities >81% could be achieved at cutoffs of 68 and 52 pmol/mU for respective immunoassay and mass spectrometry measurements.

CONCLUSIONS

Mass spectrometry-based measurements of aldosterone for the ARR provide no clear diagnostic advantage over immunoassay-based measurements. Both approaches offer limited diagnostic accuracy for the ARR as a screening test. One solution is to employ the higher cutoffs to triage patients likely to have unilateral PA for further tests and possible adrenalectomy, while using the lower cutoffs to identify others for targeted medical therapy.German Clinical Trials Register ID: DRKS00017084.

2023 Korean Endocrine Society Consensus Guidelines for the Diagnosis and Management of Primary Aldosteronism

Primary aldosteronism (PA) is a common, yet underdiagnosed cause of secondary hypertension. It is characterized by an overproduction of aldosterone, leading to hypertension and/or hypokalemia. Despite affecting between 5.9% and 34% of patients with hypertension, PA is frequently missed due to a lack of clinical awareness and systematic screening, which can result in significant cardiovascular complications. To address this, medical societies have developed clinical practice guidelines to improve the management of hypertension and PA. The Korean Endocrine Society, drawing on a wealth of research, has formulated new guidelines for PA. A task force has been established to prepare PA guidelines, which encompass epidemiology, pathophysiology, clinical presentation, diagnosis, treatment, and follow-up care. The Korean clinical guidelines for PA aim to deliver an evidence-based protocol for PA diagnosis, treatment, and patient monitoring. These guidelines are anticipated to ease the burden of this potentially curable condition.

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.

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

Background

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

Methods

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

Results

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

Conclusions

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

Who should be screened for primary aldosteronism? A comprehensive review of current evidence

Arterial hypertension is a major risk factor for cardiovascular disease. The prevalence of primary aldosteronism (PA) ranges from 5% to 10% in the general hypertensive population and is regarded as one of the most common causes of secondary hypertension. There are two major causes of PA: bilateral adrenal hyperplasia and aldosterone-producing adenoma. The diagnosis of PA comprises screening, confirmatory testing, and subtype differentiation. The Endocrine Society Practice Guidelines for the diagnosis and treatment of PA recommends screening of patients at an increased risk of PA. These categories include patients with stage 2 and 3 hypertension, drug-resistant hypertension, hypertensive with spontaneous or diuretic-induced hypokalemia, hypertension with adrenal incidentaloma, hypertensive with a family history of early onset hypertension or cerebrovascular accident at a young age, and all hypertensive first-degree relatives of patients with PA. Recently, several studies have linked PA with obstructive sleep apnea and atrial fibrillation unexplained by structural heart defects and/or other conditions known to cause the arrhythmia, which may be partly responsible for the higher rates of cardiovascular and cerebrovascular accidents in patients with PA. The aim of this review is to discuss which patients should be screened for PA, focusing not only on well-established guidelines but also on additional groups of patients with a potentially higher prevalence of PA, as has been reported in recent research.

How to Explore an Endocrine Cause of Hypertension

Hypertension (HTN) is the most frequent modifiable risk factor in the world, affecting almost 30 to 40% of the adult population in the world. Among hypertensive patients, 10 to 15% have so-called “secondary” HTN, which means HTN due to an identified cause. The most frequent secondary causes of HTN are renal arteries abnormalities (renovascular HTN), kidney disease, and endocrine HTN, which are primarily due to adrenal causes. Knowing how to detect and explore endocrine causes of hypertension is particularly interesting because some causes have a cure or a specific treatment available. Moreover, the delayed diagnosis of secondary HTN is a major cause of uncontrolled blood pressure. Therefore, screening and exploration of patients at risk for secondary HTN should be a serious concern for every physician seeing patients with HTN. Regarding endocrine causes of HTN, the most frequent is primary aldosteronism (PA), which also is the most frequent cause of secondary HTN and could represent 10% of all HTN patients. Cushing syndrome and pheochromocytoma and paraganglioma (PPGL) are rarer (less than 0.5% of patients). In this review, among endocrine causes of HTN, we will mainly discuss explorations for PA and PPGL.

Draft of the clinical practice guidelines “Adrenal incidentaloma”

The wider application and technical improvement of abdominal imaging procedures in recent years has led to an increasingly frequent detection of adrenal gland masses — adrenal incidentaloma, which have become a common clinical problem and need to be investigated for evidence of hormonal hypersecretion and/or malignancy. Clinical guidelines are the main working tool of a practicing physician. Laconic, structured information about a specific nosology, methods of its diagnosis and treatment, based on the principles of evidence-based medicine, make it possible to give answers to questions in a short time, to achieve maximum efficiency and personalization of treatment. These clinical guidelines include data on the prevalence, etiology, radiological features and assessment of hormonal status of adrenal incidentalomas. In addition, this clinical practice guideline provides information on indications for surgery, postoperative rehabilitation and follow-up.

The Association between eGFR and the Aldosterone-to-Renin Ratio and Its Effect on Screening for Primary Aldosteronism

OBJECTIVES

Long-term exposure to excessive aldosterone secretion from the adrenal gland may cause renal damage in patients with primary aldosteronism (PA). The aldosterone-to-renin ratio (ARR) may be significantly affected by renal function, especially in patients with renal damage related to long-term PA. The objective of this study was to investigate the association between the estimated glomerular filtration rate (eGFR) and ARR as well as its effect on screening for PA.

METHODS

This study was performed in Zhongshan Hospital, Fudan University, China. 803 patients with hypertension were consecutively recruited from 2012 to 2015. All participants underwent routine biochemical measurements, including plasma renin activity (PRA) and plasma aldosterone concentration (PAC). In all patients with a PAC higher than 10 ng/dl, a saline perfusion test was conducted, and a CT scan or adrenal venous sampling was also performed if needed. Receiver operating characteristic (ROC) analysis was conducted in all eGFR < 90 and eGFR ≥ 90 groups separately to determine the optimal cut-off values of ARR.

RESULTS

The optimal cut-off point for PA was an ARR of 40 ng/dl per ng/ml.h in the whole population, 52 ng/dl per ng/ml.h in subjects with an eGFR higher than 90 ml/min/1.73 m², and 18 ng/dl per ng/ml.h in subjects with an eGFR lower than 90 ml/min/1.73 m². Patients with an eGFR higher than 90 ml/min/1.73 m² had significantly lower PRA and higher ARR levels than patients with an eGFR lower than 90 ml/min/1.73 m² (P < 0.05).

CONCLUSIONS

Unsuppressed renin and lower ARR levels were associated with decreased eGFR in patients with primary aldosteronism. Diagnostic criteria of ARR by stratified eGFR may be an optimal strategy for the screening of primary aldosteronism.

A short review of primary aldosteronism in a question and answer fashion

OBJECTIVES

The aim of this study was to present up to date information concerning the diagnosis and treatment of primary aldosteronism (PA). PA is the most common cause of endocrine hypertension. It has been reported up to 24% of selective referred hypertensive patients.

METHODS

We did a search in Pub-Med and Google Scholar using the terms: PA, hyperaldosteronism, idiopathic adrenal hyperplasia, diagnosis of PA, mineralocorticoid receptor antagonists, adrenalectomy, and surgery. We also did cross-referencing search with the above terms. We had divided our study into five sections: Introduction, Diagnosis, Genetics, Treatment, and Conclusions. We present our results in a question and answer fashion in order to make reading more interesting.

RESULTS

PA should be searched in all high-risk populations. The gold standard for diagnosis PA is the plasma aldosterone/plasma renin ratio (ARR). If this test is positive, then we proceed with one of the four confirmatory tests. If positive, then we proceed with a localizing technique like adrenal vein sampling (AVS) and CT scan. If the lesion is unilateral, after proper preoperative preparation, we proceed, in adrenalectomy. If the lesion is bilateral or the patient refuses or is not fit for surgery, we treat them with mineralocorticoid receptor antagonists, usually spironolactone.

CONCLUSIONS

Primary aldosteronism is the most common and a treatable case of secondary hypertension. Only patients with unilateral adrenal diseases are eligible for surgery, while patients with bilateral and non-surgically correctable PA are usually treated by mineralocorticoid receptor antagonist (MRA). Thus, the distinction between unilateral and bilateral aldosterone hypersecretion is crucial.

Effectiveness of Thermal Ablation for Aldosterone-Producing Adrenal Adenoma: A Systematic Review and Meta-Analysis of Clinical and Biochemical Parameters

PURPOSE

To assess the effectiveness of thermal ablation for aldosterone-producing adrenal adenoma.

MATERIALS AND METHODS

A systematic search of the PubMed and CINAHL databases was performed to identify studies of thermal ablation for adrenal adenomas. Random effects meta-analysis models were used to compare pre- and post-treatment values of the following outcomes: systolic blood pressure (SBP), diastolic blood pressure (DBP), use of antihypertensive medications, and biochemical parameters (plasma aldosterone levels, aldosterone-to-renin ratio, and potassium levels). The rate of hypertension (HTN) resolution and improvement were also evaluated.

RESULTS

A total of 89 patients from 7 studies were included in the analysis. The mean postablation follow-up duration was 45.8 months. Pooled data analysis revealed a statistically significant decrease in SBP (-29.06 mm Hg; 95% confidence interval [CI], -33.93 to -24.19), DBP (-16.03 mm Hg; 95% CI, -18.33 to -13.73), and the number of antihypertensive medications used (-1.43; 95% CI, -1.97 to -0.89) after ablation. Biochemical parameters had returned to normal ranges after ablation in all studies. The cumulative rate of resolution or improvement in HTN status was 75.3%. On metaregression analysis, there was no statistically significant association between postablation blood pressure changes or serum aldosterone levels and study follow-up duration.

CONCLUSIONS

Thermal ablation for aldosterone-producing adrenal adenoma can be effective in controlling blood pressure, reducing the need for antihypertensive medications, and normalizing hormone secretion. Further higher-quality evidence is needed to confirm these results.

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

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

Association of the plasma aldosterone concentration, left atrial deformation and ambulatory blood pressure in never-treated early hypertensive patients

Left atrial (LA) strain is known to exhibit an early progressive reduction in hypertensive patients with diastolic dysfunction. However, an association of the renin-angiotensin-*aldosterone system (RAAS) with LA deformation has not been found in these patients. We aimed to investigate the association of plasma aldosterone concentration (PAC) and 24-hour ambulatory blood pressure monitoring (ABPM) with LA and left ventricle (LV) deformation in never-treated early hypertensive patients. This cross-sectional study included 101 never-treated subjects who were registered in a working group at The Catholic University of Korea. The patients were divided into a hypertension group (n = 71), which was defined as having a systolic blood pressure (BP) ≥130 mm Hg and/or a diastolic BP ≥80 mm Hg based on ABPM, and a control group (n = 30). Enrolled patients underwent conventional and speckle tracking echocardiography, ABPM, and measurement of pulse wave velocity, PAC, and plasma renin activity. Compared with the control group, the hypertension group had significantly increased PAC, global longitudinal strain (GLS), atrial reservoir strain, atrial pump strain, and atrial systolic strain rate. LA pump strain was independently associated with nighttime systolic BP. PAC was correlated with GLS but not LA deformation in hypertensive patients without clinically apparent target organ damage. The raised LV pressure secondary to the nocturnal systemic pressure overload might be more strongly associated with LA deformation than with the RAAS.

Effect of Combined Hormonal Replacement Therapy on the Aldosterone/Renin Ratio in Postmenopausal Women

BACKGROUND

Plasma aldosterone/renin ratio (ARR) is the most popular screening test for primary aldosteronism (PA). Because both estrogen and progesterone (including in oral contraceptive agents) affect aldosterone and renin levels, we studied the effects of combined hormonal replacement therapy (HRT) on ARR; renin was measured as both direct renin concentration (DRC) and plasma renin activity (PRA).

METHODS

Fifteen normotensive, healthy postmenopausal women underwent measurement (seated, midmorning) of plasma aldosterone, DRC, PRA, electrolytes, and creatinine and urinary aldosterone, cortisol, electrolytes, and creatinine at baseline and after 2 weeks and 6 weeks of treatment with combined HRT (conjugated estrogens 0.625 mg and medroxyprogesterone 2.5 mg daily).

RESULTS

Combined HRT was associated with statistically significant increases in aldosterone [median (range): baseline, 150 (85 to 600); 2 weeks, 230 (129 to 790); 6 weeks, 434 (200 to 1200) pmol/L; P < 0.001 (Friedman test)] and PRA [2.3 (1.2 to 4.3), 3.8 (1.4 to 7.0), 5.1 (1.4 to 10.8) ng/mL/h, respectively; P < 0.001] but decreases in DRC [21 (10 to 31), 21 (10 to 39), and 14 (8.0 to 30) mU/L, respectively; P < 0.01], leading to increases in ARR calculated by DRC [7.8 (3.6 to 34.8), 11.4 (5.4 to 48.5), and 30.4 (10.5 to 90.2), respectively; P < 0.001]. The ARR calculated by DRC exceeded the cutoff value (70) in three patients after 6 weeks. There were no significant changes in ARR calculated by PRA [79 (26 to 184), 91 (23 to 166), and 88 (50 to 230), respectively; P = 0.282], plasma electrolytes and creatinine, or any urinary measurements.

CONCLUSION

The combined oral HRT used in this study is capable of significantly increasing ARR with a risk of false-positive results during screening for PA but only if DRC (and not PRA) is used to calculate the ratio.

Effect of Moxonidine on the Aldosterone/Renin Ratio in Healthy Male Volunteers

BACKGROUND

The most popular screening test for primary aldosteronism is the plasma aldosterone/renin ratio (ARR). Medications, dietary sodium, posture, and time of day all affect renin and aldosterone levels and can result in false-negative or false-positive ARRs if not controlled. Most antihypertensive medications affect the ARR and can interfere with interpretation of results. To our knowledge, no study has been undertaken to evaluate the effects of moxonidine on the ARR.

METHODS

Normotensive, nonmedicated male volunteers (n = 20) underwent measurement (seated, midmorning) of plasma aldosterone (by high-performance liquid chromatography-tandem mass spectrometry), direct renin concentration (DRC), plasma renin activity (PRA), cortisol, electrolytes and creatinine; and urinary aldosterone, cortisol, electrolytes and creatinine at baseline and after 1 week of moxonidine at 0.2 mg/d and a further 5 weeks at 0.4 mg/d.

RESULTS

Compared with baseline, despite the expected significant falls in both systolic and diastolic blood pressure, levels of plasma aldosterone [median, 134 (range, 90 to 535) pmol/L], DRC [20 (10 to 37) mU/L], PRA [2.2 (1.0-3.8) ng/mL/h], and ARR using either DRC [8.0 (4.4 to 14.4)] or PRA [73 (36 to 218)] were not significantly changed after either 1 [135 (98-550) pmol/L, 20 (11-35) mU/L, 2.0 (1.2-4.1) ng/mL/h, 8.8 (4.2 to 15.9), and 73 (32-194), respectively] or 6 weeks [130 (90-500) pmol/L, 22 (8 to 40) mU/L, 2.1 (1.0 to 3.2) ng/mL/h, 7.7 (4.3 to 22.4), and 84 (32 to 192), respectively] of moxonidine. There were no changes in any urinary measurements.

CONCLUSION

Moxonidine was associated with no significant change in the ARR and may therefore be a good option for maintaining control of hypertension when screening for primary aldosteronism.

Screening for primary aldosteronism using the newly developed IDS-iSYS® automated assay system

BACKGROUND

The recommended approach to screening for primary aldosteronism (PA) in at-risk populations is to determine the ratio of aldosterone concentration (serum (SAC)/plasma (PAC)) to renin measured in plasma as activity (PRA) or concentration (DRC). However, lack of assay standardisation mandates the need for method-specific decision thresholds and clinical validation in the local population.

AIM

The study objective was to establish method-specific aldosterone: renin ratio (ARR) cut-offs for PA in men and women using the IDS-iSYS® assay system (IDS plc).

METHODS

A prospective cohort study design was used. PAC and DRC were measured immunochemically in ethylenediamine-tetraacetic acid (EDTA) plasma on the IDS-iSYS® instrument.

RESULTS

A total of 437 subjects (218 men, 219 women) were recruited including: healthy normotensive volunteers (n=266) and women taking the oral contraceptive pill (OCP; n=15); patients with essential hypertension (EH; n=128); confirmed PA (n=16); adrenal cortical carcinoma (ACC; n=3); Addison's disease (AD; n=4) and phaeochromocytoma/paraganglioma (PPGL; n=5). In this population, an ARR cut-off at >37.4 pmol/mIU provided 100% diagnostic sensitivity, 96% specificity and positive likelihood ratio for PA of 23:1. When the ARR decision threshold was stratified according to gender, a cut-off of >26.1 pmol/mIU in men and >113.6 pmol/mIU in women resulted in diagnostic sensitivity and specificity of 100%.

CONCLUSION

This study demonstrates that decision thresholds for PA should not only be method-specific but also gender-specific. However, given the small number of PA patients (n=16), particularly women (n=4), further validation through a prospective study with a larger PA cohort is required before the thresholds presented here could be recommended for routine clinical use.

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.

Postoperative Care Following Pituitary Surgery

Patients undergoing surgery for pituitary tumors represent a heterogeneous population each with unique clinical, biochemical, radiologic, pathologic, neurologic, and/or ophthalmologic considerations. The postoperative management of patients following pituitary surgery often occurs in the context of a dynamic state of the hypothalamic-pituitary-end organ axis. Consequently, a significant component of the postoperative care of these patients focuses on vigilant screening and observation for neuroendocrinologic perturbations such as varying degrees of hypopituitarism and disorders of water balance (diabetes insipidus and the syndrome of inappropriate antidiuretic hormone). Additionally, one must be cognizant of other potential complications specific to the transsphenoidal approach for tumor removal including cerebrospinal fluid leakage and meningitis. This review addresses the postoperative management of patients undergoing pituitary surgery with an emphasis on careful screening and recognition of complications.

The Aldosterone/Renin Ratio as a Diagnostic Tool for the Diagnosis of Primary Hypoaldosteronism in Newborns and Infants

BACKGROUND/AIMS

Primary hypoaldosteronism is a rare inborn disorder with life-threatening symptoms in newborns and infants due to an aldosterone synthase defect. Diagnosis is often difficult as the plasma aldosterone concentration (PAC) can remain within the normal range and thus lead to misinterpretation and delayed initiation of life-saving therapy. We aimed to test the eligibility of the PAC/plasma renin concentration (PRC) ratio as a tool for the diagnosis of primary hypoaldosteronism in newborns and infants. Meth ods: Data of 9 patients aged 15 days to 12 months at the time of diagnosis were collected. The diagnosis of primary hypoaldosteronism was based on clinical and laboratory findings over a period of 12 years in 3 different centers in Switzerland. To enable a valid comparison, the values of PAC and PRC were correlated to reference methods.

RESULTS

In 6 patients, the PAC/PRC ratio could be determined and showed constantly decreased values <1 (pmol/l)/(mU/l). In 2 patients, renin was noted as plasma renin activity (PRA). PAC/PRA ratios were also clearly decreased. The diagnosis was subsequently genetically confirmed in 8 patients.

CONCLUSION

A PAC/PRC ratio <1 pmol/mU and a PAC/PRA ratio <28 (pmol/l)/(ng/ml × h) are reliable tools to identify primary hypoaldosteronism in newborns and infants and help to diagnose this life-threatening disease faster.

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.

The Management of Primary Aldosteronism: Case Detection, Diagnosis, and Treatment: An Endocrine Society Clinical Practice Guideline

OBJECTIVE

To develop clinical practice guidelines for the management of patients with primary aldosteronism.

PARTICIPANTS

The Task Force included a chair, selected by the Clinical Guidelines Subcommittee of the Endocrine Society, six additional experts, a methodologist, and a medical writer. The guideline was cosponsored by American Heart Association, American Association of Endocrine Surgeons, European Society of Endocrinology, European Society of Hypertension, International Association of Endocrine Surgeons, International Society of Endocrinology, International Society of Hypertension, Japan Endocrine Society, and The Japanese Society of Hypertension. The Task Force received no corporate funding or remuneration.

EVIDENCE

We searched for systematic reviews and primary studies to formulate the key treatment and prevention recommendations. We used the Grading of Recommendations, Assessment, Development, and Evaluation group criteria to describe both the quality of evidence and the strength of recommendations. We used "recommend" for strong recommendations and "suggest" for weak recommendations.

CONSENSUS PROCESS

We achieved consensus by collecting the best available evidence and conducting one group meeting, several conference calls, and multiple e-mail communications. With the help of a medical writer, the Endocrine Society's Clinical Guidelines Subcommittee, Clinical Affairs Core Committee, and Council successfully reviewed the drafts prepared by the Task Force. We placed the version approved by the Clinical Guidelines Subcommittee and Clinical Affairs Core Committee on the Endocrine Society's website for comments by members. At each stage of review, the Task Force received written comments and incorporated necessary changes.

CONCLUSIONS

For high-risk groups of hypertensive patients and those with hypokalemia, we recommend case detection of primary aldosteronism by determining the aldosterone-renin ratio under standard conditions and recommend that a commonly used confirmatory test should confirm/exclude the condition. We recommend that all patients with primary aldosteronism undergo adrenal computed tomography as the initial study in subtype testing and to exclude adrenocortical carcinoma. We recommend that an experienced radiologist should establish/exclude unilateral primary aldosteronism using bilateral adrenal venous sampling, and if confirmed, this should optimally be treated by laparoscopic adrenalectomy. We recommend that patients with bilateral adrenal hyperplasia or those unsuitable for surgery should be treated primarily with a mineralocorticoid receptor antagonist.

Endocrine Dysfunction in Diamond-Blackfan Anemia (DBA): A Report from the DBA Registry (DBAR)

BACKGROUND

Diamond-Blackfan anemia (DBA) is a rare inherited bone marrow failure syndrome. The mainstays of treatment involve chronic red cell transfusions, long-term glucocorticoid therapy, and stem cell transplantation. Systematic data concerning endocrine function in DBA are limited. We studied patients in the DBA Registry (DBAR) of North America to assess the prevalence of various endocrinopathies.

PROCEDURE

In a pilot study, retrospective data were collected for 12 patients with DBA. Subsequently, patients with DBA aged 1-39 years were recruited prospectively. Combined, 57 patients were studied; 38 chronically transfused, 12 glucocorticoid-dependent, and seven in remission. Data were collected on anthropometric measurements, systematic screening of pituitary, thyroid, parathyroid, adrenal, pancreatic, and gonadal function, and ferritin levels. Descriptive statistics were tabulated and group differences were assessed.

RESULTS

Fifty-three percent of patients had ≥ 1 endocrine disorder, including adrenal insufficiency (32%), hypogonadism (29%), hypothyroidism (14%), growth hormone dysfunction (7%), diabetes mellitus (2%), and/or diabetes insipidus (2%). Ten of the 33 patients with available heights had height standard deviation less than -2. Low 25-hydroxy vitamin D (25(OH)D) levels were present in 50%. A small proportion also had osteopenia, osteoporosis, or hypercalciuria. Most with adrenal insufficiency were glucocorticoid dependent; other endocrinopathies were more common in chronically transfused patients.

CONCLUSIONS

Endocrine dysfunction is common in DBA, as early as the teenage years. Although prevalence is highest in transfused patients, patients taking glucocorticoids or in remission also have endocrine dysfunction. Longitudinal studies are needed to better understand the etiology and true prevalence of these disorders.

Adrenal incidentaloma: evaluation and management

Adrenal incidentalomas are adrenal masses discovered incidental to imaging studies performed for reasons unrelated to adrenal pathology. Although most adrenal incidentalomas are non-functioning benign adenomas, their increasing prevalence presents diagnostic and therapeutic challenges. The assessment of adrenal incidentalomas is aimed at deciding whether or not the tumour should be surgically removed. Adrenalectomy is indicated for phaeochromocytoma, other symptomatic hormone-secreting tumours and those with a high risk of malignancy. Biochemical screening for tumour hypersecretion is mandatory in all adrenal incidentalomas, since hormone secreting tumours may be clinically silent. The diagnosis of phaeochromocytoma is of paramount importance because of its life-threatening complications. Non-functioning adrenal incidentalomas need assessment for risk of malignancy, and this is based on the size of the tumour and its imaging characteristics. An observational policy with periodic radiological and biochemical reassessment is pursued in patients with non-functioning incidentalomas with low malignancy risk. The duration and frequency of reassessment remains unclear, as the natural history of adrenal incidentalomas has yet to be clearly defined, and there is a lack of controlled studies comparing surgical intervention with observation. However, the possibility of acquiring autonomous hypersecretion or conversion to malignancy in an incidentaloma diagnosed to be a benign non-functioning lesion is very low, and most patients may be safely discharged after an initial follow-up period of 2 years.

Hyperaldosteronism: diagnosis, lateralization, and treatment

Primary hyperaldosteronism is an important and commonly unrecognized secondary cause of hypertension. This article provides an overview of the current literature with respect to screening, diagnosis, and lateralization. Selection and outcomes of medical and surgical treatment are discussed.

[Clinical evaluation of the renin-aldosterone system: comparison of two methods in different clinical conditions]

INTRODUCTION

Measurement of plasma aldosterone/renin ratio is the key step in the diagnosis of primary aldosteronism.

AIM

The aim of the authors was to analyze and compare the diagnostic utility of plasma aldosterone/renin activity and plasma aldosterone/renin concentration ratios.

METHODS

Plasma aldosterone and plasma renin activity were determined by radioimmunoassays and plasma renin concentration was measured by immunoradiometric assay in 134 subjects (80 women and 54 men, aged 46±15.5 years) including 49 healthy blood donors (control group), 59 patients with hypertension (25 treated and 34 untreated) and 26 patients with incidentally discovered adrenal adenomas.

RESULTS

There was a weak correlation (r = 0.59) between plasma renin activity and plasma renin concentration in the lower range (plasma renin activity, 0.63±0.41 ng/ml/h; plasma renin concentration, 8.1±4.9 ng/l). Considering the cut-off value of plasma aldosterone/renin ratios determined in controls (plasma aldosterone/renin activity ratio, 30 ng/dl/ng/ml/h; plasma aldosterone/renin concentration ratio, 3.0 ng/dl/ng/l), high proportion of falsely positive results were found among patients on beta-receptor blocker therapy (plasma aldosterone/renin activity ratio, 22.2%; plasma aldosterone/renin concentration ratio, 44.4%)

CONCLUSION

The widely used plasma aldosterone/renin activity ratio can only be replaced with plasma aldosterone/renin concentration ratio with precaution on different clinical conditions.

Aldosterone, Plasma Renin Activity, and Aldosterone/Renin Ratio in a Normotensive Healthy Pediatric Population

Primary aldosteronism is an important cause of secondary hypertension and is suspected in adults with an aldosterone/renin ratio ≥25. The normal aldosterone/renin ratio is unknown in children. The aim was to establish serum aldosterone, plasma renin activity, and aldosterone/renin ratio values in a healthy pediatric population. A cross-sectional study was performed in 211 healthy normotensive children (4 to 16 years old). Two subgroups of normotensive children were obtained: with hypertensive parents (NH) (n=113) and normotensive parents (n=98). Blood samples for measuring serum aldosterone, plasma renin activity, aldosterone/renin ratio, and DNA were collected. In subjects with aldosterone/renin ratio ≥25, the chimeric CYP11B1/CYP11B2 gene was investigated by long-extension PCR. Results are expressed as median [Q 1 –Q 3 ]. NH and normotensive parents groups were similar in serum aldosterone (6.5 [3.6 to 9.0] ng/dL versus 6.5 [2.9 to 9.7] ng/dL; P =0.968) and plasma renin activity (2.3 [1.6 to 3.1] versus 2.4 [1.7 to 3.7] ng/mL per hour; P =0.129). The aldosterone/renin ratio was higher in the NH group, but this difference did not reach statistical significance (2.8 [1.9 to 4.1] versus 2.5 [1.4 to 4.0], P =0.104). In one subject of the NH group, the chimeric CYP11B1/CYP11B2 gene was detected. We demonstrated that normal aldosterone/renin ratio values in a healthy pediatric population without NH were lower than those reported for an adult normotensive population.

Effect of atenolol on aldosterone/renin ratio calculated by both plasma Renin activity and direct Renin concentration in healthy male volunteers

BACKGROUND

The most popular screening test for primary aldosteronism (PAL) is the plasma aldosterone to renin ratio (ARR). Medications, dietary sodium, posture, and time of day all affect renin and aldosterone levels and can result in false-negative or -positive ARR if not controlled. Opinions are divided on whether beta-adrenoreceptor blockers significantly affect the ARR.

METHODS

Normotensive, nonmedicated male volunteers (n = 21) underwent measurement (seated, midmorning) of plasma aldosterone (by HPLC-tandem mass spectrometry), direct renin concentration (DRC), renin activity (PRA), cortisol, electrolytes, and creatinine and urinary aldosterone, cortisol, electrolytes, and creatinine at baseline, and after 1 wk (25 mg daily) and 4 wk (50 mg daily for three additional weeks) of atenolol.

RESULTS

Compared with baseline, levels of aldosterone, DRC, and PRA were lower (P < 0.001) after both 1 and 4 wk [median (25-75th percentiles): baseline, 189 (138-357) pmol/liter, 40 (30-46) mU/liter, and 4.6 (2.7-5.8) ng/ml x h; 1 wk, 166 (112-310) pmol/liter, 34 (30-40) mU/liter, and 2.6 (2.0-3.1) ng/ml x h; 4 wk, 136 (97-269) pmol/liter, 16 (13-23) mU/liter, and 2.1(1.7-2.6) ng/ml x h, respectively]. ARR was significantly higher after 1 wk compared with baseline when calculated using PRA [61 (30-73) vs. 65 (44-130), P < 0.01] but not DRC [5 (4-7) vs. 5 (4-8)]. At 4 wk, ARR calculated by both PRA [78 (49-125)] and DRC [8 (6-14)] were significantly higher (P < 0.001) compared with baseline, and cortisol levels were significantly lower [92 (68-100) vs. 66 (48-91) ng/ml, P < 0.01]. There were no changes in plasma sodium, potassium, creatinine, or any urinary measurements.

CONCLUSION

beta-Blockers can significantly raise the ARR and thereby increase the risk of false positives during screening for PAL.

Are plasma renin activity and aldosterone levels useful as a screening test to differentiate between unilateral and bilateral renal artery stenosis in hypertensive patients?

OBJECTIVE

To evaluate the serum aldosterone (Ald)/plasmatic renin activity (PRA) ratio as a surrogate marker of renin-angiotensin-aldosterone system status in unilateral (Uni)- and bilateral (Bi)-renal artery stenosis (RAS).

METHODS

Seven hundred and eight hypertensive patients (HTP) were studied. Intermediate and high pretest risk of RAS was detected in 66 HTP who subsequently underwent renal gadolinium-enhanced magnetic resonance and arteriography. After application of exclusion criteria 51 HTP remained: 16 with Uni-RAS, 16 with Bi-RAS and 19 essential hypertensives with normal arteries. Nineteen normotensive individuals were also studied. Ald and PRA were determined before and after stenosis resolution by balloon angioplasty and stent implantation.

RESULTS

Ald/PRA (ng/dl per (ng/ml per h(-1))) was markedly high in Bi-RAS (5.92 +/- 2.30, P < 0.001), and markedly low in Uni-RAS (0.38 +/- 0.17, P < 0.001) versus essential hypertensives (1.52 +/- 2.02). Multilevel likelihood ratios for Bi-RAS were positive for Ald/PRA higher than 3.6, negative for Ald/PRA lower than 0.2, and neutral for Ald/PRA at least 0.2 and 3.6 or less. ROC analysis identified Ald/PRA lower than 0.5 and Ald/PRA higher than 3.7 to have the best sensitivity and specificity to detect Uni-RAS and Bi-RAS, respectively. In Uni-RAS, but not in Bi-RAS, postinterventional PRA was significantly lower than basal PRA. In Uni-RAS and Bi-RAS, postinterventional Ald was approximately 30% and approximately three times lower than basal Ald, respectively. In essential hypertensives, PRA and Ald showed no changes in the same period.

CONCLUSION

In the population studied, Ald, PRA and Ald/PRA were significantly different among essential hypertensives, and HTP with Uni-RAS or Bi-RAS. Studies with a higher number of patients will allow exploration of the usefulness of pharmacologic aldosterone blockade in Bi-RAS, and to assess the relevance of Ald/PRA to differentiate Uni-RAS from Bi-RAS.

Case detection, diagnosis, and treatment of patients with primary aldosteronism: an endocrine society clinical practice guideline

OBJECTIVE

Our objective was to develop clinical practice guidelines for the diagnosis and treatment of patients with primary aldosteronism.

PARTICIPANTS

The Task Force comprised a chair, selected by the Clinical Guidelines Subcommittee (CGS) of The Endocrine Society, six additional experts, one methodologist, and a medical writer. The Task Force received no corporate funding or remuneration.

EVIDENCE

Systematic reviews of available evidence were used to formulate the key treatment and prevention recommendations. We used the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) group criteria to describe both the quality of evidence and the strength of recommendations. We used "recommend" for strong recommendations and "suggest" for weak recommendations.

CONSENSUS PROCESS

Consensus was guided by systematic reviews of evidence and discussions during one group meeting, several conference calls, and multiple e-mail communications. The drafts prepared by the task force with the help of a medical writer were reviewed successively by The Endocrine Society's CGS, Clinical Affairs Core Committee (CACC), and Council. The version approved by the CGS and CACC was placed on The Endocrine Society's Web site for comments by members. At each stage of review, the Task Force received written comments and incorporated needed changes.

CONCLUSIONS

We recommend case detection of primary aldosteronism be sought in higher risk groups of hypertensive patients and those with hypokalemia by determining the aldosterone-renin ratio under standard conditions and that the condition be confirmed/excluded by one of four commonly used confirmatory tests. We recommend that all patients with primary aldosteronism undergo adrenal computed tomography as the initial study in subtype testing and to exclude adrenocortical carcinoma. We recommend the presence of a unilateral form of primary aldosteronism should be established/excluded by bilateral adrenal venous sampling by an experienced radiologist and, where present, optimally treated by laparoscopic adrenalectomy. We recommend that patients with bilateral adrenal hyperplasia, or those unsuitable for surgery, optimally be treated medically by mineralocorticoid receptor antagonists.

The aldosterone to renin ratio in the evaluation of patients with incidentally detected adrenal masses

Incidentally discovered adrenal masses are diagnosed with increasing frequency, especially among patients with hypertension. Thus, a reliable screening test for primary hyperaldosteronism (PA) is essential to avoid unnecessary diagnostic procedures to this population. The aim of the present study is the evaluation of aldosterone to renin ratio (ARR), using plasma renin concentration, in the diagnostic algorithm of patients with adrenal incidentaloma. A total of 123 individuals were studied: 17 patients with proven PA (age 55.5 +/- 1.4 years), 27 patients with nonfunctioning adrenal incidentaloma (age 60.3 +/- 1.8 years, 14 hypertensives and 13 normotensives) and 79 control subjects (age 58.7 +/- 1.4 years, 27 hypertensives and 52 normotensives). A receiver operating characteristic (ROC) analysis disclosed that an ARR > or =32 combines a sensitivity of 100% with a specificity of 96.2% for the diagnosis of PA. No difference in AlphaRR between hypertensive and normotensive individuals harbouring an adrenal incidentaloma and hypertensive and normotensive controls was found. Patients with adrenal incidentalomas with subtle glucocorticoid hypersecretion demonstrated similar ARR compared to patients with normal cortisol secretion. In conclusion, ARR is reliable for the exclusion of PA in patients with adrenal incidentalomas. Furthermore, subtle aldosterone hypersecretion, as indicated by increased ARR, in patients with adrenal incidentalomas is not associated with the presence of hypertension or subtle glucocorticoid hypersecretion.

Primary aldosteronism: current knowledge and controversies in Conn's syndrome

Primary aldosteronism has been recognized as a common cause of secondary hypertension, accounting for approximately 10% of the hypertensive population. Screening should be applied in hypertensive patients presenting with one of the following: hypokalemia, refractory hypertension, suggestive family history, or an incidentally detected adrenal mass. The most advocated screening test at present is the aldosterone-to-renin ratio, which has a high sensitivity but low specificity. The specificity increases if patients with low aldosterone concentrations are excluded. Published cut-off values vary depending on the hormone assay and the investigated population. Before screening, antihypertensive treatment, especially aldosterone antagonists and beta-blockers, should be discontinued. A pathologic result requires additional work up to prove mineralocorticoid excess. Subtype differentiation is performed by adrenal venous sampling combined with imaging (CT or MRI). One-third of cases are due to aldosterone-producing adenomas, for which the preferred treatment is laparoscopic adrenalectomy. Bilateral adrenal hyperplasia (idiopathic aldosteronism) underlies two-thirds of cases and requires treatment with aldosterone antagonists. Treatment is started with low doses of spironolactone (25-50 mg once daily), which often results in substantial improvements in hypertension.

Screening for primary aldosteronism

Normokalaemic manifestation of primary aldosteronism is a frequent cause of secondary hypertension. It occurs in approximately 5-12% of all patients with hypertension, primarily patients with severe and uncontrolled blood pressure. Main causes are bilateral adrenal hyperplasia (2/3 of cases) and aldosterone-producing adenoma (1/3 of cases). Screening is performed by measurement of the aldosterone/renin ratio, which is raised in affected patients. Suspicion of primary aldosteronism due to a pathological ratio requires confirmatory testing e.g. by saline infusion test or fludrocortisone suppression test. If the diagnosis is confirmed, the underlying cause of aldosterone excess needs to be identified because therapy differs. First, adrenal imaging (CT/MRI) is performed, which is followed by postural testing in cases with a unilateral lesion. Concordant results confirm the diagnosis of an aldosterone-producing adenoma and allow treatment to proceed to adrenalectomy. In cases of equivocal results or normal/bilaterally enlarged adrenal glands on imaging, adrenal venous sampling must be performed for subtype differentiation.

Automated Chemiluminescence-Immunoassay for Aldosterone during Dynamic Testing: Comparison to Radioimmunoassays with and without Extraction Steps

Background: Measurements of aldosterone have become more common since the recognition that primary aldosteronism is a more frequent cause of hypertension than previously believed. Our aim was to compare concentrations reported by 4 assays for samples obtained after saline infusion during dynamic testing.

Methods: We tested 104 participants (27 with primary aldosteronism, 30 with essential hypertension, and 47 healthy controls) with the intravenous saline infusion test (2.0 L isotonic saline over 4 h), with repetitive sampling. In all blood samples, aldosterone concentration was measured by an in-house RIA after extraction and chromatography, by 2 commercially available RIAs without extraction (Aldosterone Maia, Adaltis; Active Aldosterone, Diagnostics Systems Laboratories) and by an automated CLIA (Advantage, Nichols Institute Diagnostics).

Results: Correlation coefficients for results of pairs of assays ranged from 0.74 to 0.98. Agreement between commercial assays and in-house RIA was best at the low to intermediate concentrations after saline infusion. Mean (SD) Adaltis and DSL RIA results were 2- to 3-times higher [healthy participants: 78 (25) ng/L and 56 (18) ng/L, respectively] than those obtained by Nichols CLIA [17 (8) ng/L] and in-house RIA [23 (18) ng/L]. Aldosterone concentrations measured by the Nichols CLIA were below the limit of detection (limit of the blank) in 27 of 47 healthy participants.

Conclusions: Aldosterone concentrations reported by the Adaltis and DSL nonextraction RIAs were consistently higher than those produced by the Nichols CLIA and the in-house RIA. The convenient Nichols CLIA showed better agreement with the in-house RIA, but the concentrations in healthy participants were frequently undetectable by this method. Uncritical application of cutoff values from the literature must be avoided.

Diagnostic Value of Biochemical Parameters in the Differential Diagnosis of an Adrenal Mass

In patients with an adrenal mass, hormonally active tumors including pheochromocytomas as well as aldosterone- and cortisol-secreting adenomas need to be considered. Several studies have demonstrated that metanephrines, which are the metabolites of catecholamines, are reliable parameters for the diagnosis of pheochromocytoma. In patients with an adrenal mass, we found plasma metanephrines, measured by a newly available radioimmunoassay, to be highly sensitive and specific for pheochromocytomas, with a better accuracy than any other biochemical parameter. The plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio is an established screening tool for primary hyperaldosteronism. However, determination of active renin concentration (ARC) in contrast to PRA may offer advantages in regard to processing and standardization. We found a PAC to ARC ratio of >62 in patients with PAC levels>200 ng/L to be a reliable screening method for primary hyperaldosteronism in patients with adrenal masses. The screening for hypercortisolism relies on excess urinary cortisol secretion, loss of the physiological feedback during dexamethasone challenge, and loss of the circadian rhythm. Because urinary-free cortisol may not identify subclinical Cushing's syndrome, in which hypercortisolism is still mild, the 1-mg dexamethasone suppression test has been recommended in all patients with incidentally detected masses. Alternatively, late-night cortisol levels in saliva have been found to have a high sensitivity and specificity for the diagnosis of Cushing's syndrome. In summary, in patients with an adrenal mass, hormonally active adrenal tumors can be excluded with high certainty using a few highly reliable biochemical parameters.

Optimal use and interpretation of the aldosterone renin ratio to detect aldosterone excess in hypertension

With the introduction of the aldosterone/renin ratio as a screening test, the detection rate of primary aldosteronism has increased considerably. Nevertheless, no consensus has so far been reached regarding the cutoff points, operating characteristics or indeed even the reference values for reporting the aldosterone/renin ratio using plasma active renin (ng/l or mU/l) measured by immunoradiometric assay. We review the characteristics of this ratio in normal individuals, essential hypertension and primary hyperaldosteronism in an attempt to reach an agreement regarding its optimum use and interpretation - both using the renin activity or concentration. It seems that the optimal cutoff for patients with primary aldosteronism is above 30 ng/dl per mug/l/h or 800 pmol/l per mug/l/h or 130 pmol/ng or 80 pmol/mU. We explore enhancing measures such as captopril loading or use with a plasma aldosterone cutoff as well as pitfalls with the test such as confounding medications or the need for confirmatory testing. For the latter, demonstration of autonomous aldosterone production via salt loading is widely used, but may not be most advantageous and may even be contraindicated in patients with severe hypertension. The renin stimulation test may be an alternative being safe, well tolerated, and cost effective.

Analysis of screening and confirmatory tests in the diagnosis of primary aldosteronism: need for a standardized protocol

BACKGROUND

The upright serum aldosterone/upright plasma renin activity ratio (ARR) has been recommended as a screening tool for the diagnosis of primary aldosteronism.

OBJECTIVE

We reviewed the data collected from hypertensive patients in order to define retrospectively the cut-off values and evaluate the reliability of the ARR and of the saline infusion test in the diagnosis of primary aldosteronism.

PATIENTS

In 157 patients referred to our unit with a suspicion of primary aldosteronism, 61 of whom had confirmed primary aldosteronism [26 aldosterone-producing adenoma (APA); 35 idiopathic hyperaldosteronism], the supine and upright ARR, and the ARR after the administration of captopril and losartan were calculated, and the results of the saline infusion test were analysed.

RESULTS

Choosing 40 as the cut-off value, the upright ARR had 100% sensitivity and 84.4% specificity. The post-captopril and post-losartan ARR were slightly more specific, but at the cost of a lower sensitivity. A cut-off value of 7 ng/dl for serum aldosterone at the end of the saline infusion in patients with an upright ARR of 40, gave 100% specificity and a positive predictive value. Furthermore, APA patients showed increased mean levels of aldosterone/cortisol ratio after the saline infusion test.

CONCLUSION

Our data reinforce the superiority of a standardized upright ARR as a screening test in the diagnosis of primary aldosteronism, identifying 40 as an ideal cut-off value. Saline infusion represents a useful test to confirm such a diagnosis, with a serum aldosterone level of 7 ng/dl as a satisfactory cut-off value. Some more information is obtained when the aldosterone/cortisol ratio is considered.

Adrenocortical hypertension

Primary aldosteronism, congenital adrenal hyperplasia, Cushing's syndrome, glucocorticoid-remediable aldosteronism, and corticotropin-dependent forms of adrenal pathology can cause hypertension by excessive production of adrenocortical hormones. Although traditional biochemical assays continue to be used, genetic testing has simplified the diagnosis of glucocorticoid-remediable aldosteronism. Also new interventional radiologic approaches for the diagnosis and treatment of corticotropin-dependent forms of Cushing's syndrome are available. Medical and surgical approaches, however, still remain viable options for treatment.

Effect of Aerobic Exercise Training on Renal Responses to Sodium in Hypertensives

INTRODUCTION

Aerobic exercise training has been shown to improve cardiovascular function and lower blood pressure (BP) in older adults. The exact mechanism(s) by which aerobic exercise training elicits these changes are unknown; however, it is possible that changes in renal hemodynamics may play a role.

PURPOSE

The present study was undertaken to examine the effect of aerobic exercise training on renal hemodynamics in older hypertensive individuals.

METHODS

Renal plasma flow (RPF) and glomerular filtration rate (GFR) were determined by plasma and urinary clearances of 131I-hippuran and 99mTc-DTPA after 8 d of low (20 mEq) and high (200 mEq) Na+ diets in 31 older (63 +/- 1 yr), hypertensive (152 +/- 2/88 +/- 1 mm Hg) individuals at baseline and following 6 months of aerobic exercise training (at 75% VO2max, three times a week, 40 min per session).

RESULTS

Following 6 months of aerobic exercise training, a significant increase was seen in maximal aerobic capacity (VO2max: 18.3 +/- 0.7 vs 20.7 +/- 0.7 mL.kg.min(-1), P = 0.017) as well as a significant decrease in resting systolic (152 +/- 2 vs 145 +/- 2 mm Hg, P = 0.037) and mean arterial (109 +/- 1 vs 105 +/- 1 mm Hg, P = 0.021) BP. No significant (P < 0.05) effects were seen of aerobic exercise training on RPF (208.8 +/- 12.2 vs 197.1 +/- 13.1 mL.min(-1).1.73 m(-2)), GFR (68.9 +/- 3.6 vs 69.0 +/- 3.9 mL.min(-1).1.73 m(-2)), or filtration fraction (35.3 +/- 2.3 vs 37.1 +/- 2.4%) on the low Na+ diet or RPF (210.6 +/- 12.8 vs 212.1 +/- 11.7 mL.min(-1).1.73 m(-2)), GFR (72.9 +/- 4.1 vs 77.3 +/- 4.3 mL.min(-1).1.73 m(-2)), or filtration fraction (37.1 +/- 2.5 vs 37.7 +/- 3.0%) on the high Na+ diet.

CONCLUSIONS

Our results suggest that changes in renal hemodynamics do not contribute to the reduction in resting BP in older hypertensive persons.