Further evaluation of saline infusion for the diagnosis of primary aldosteronism

Primary hyperaldosteronism secondary to right adrenal hyperplasia with non-functioning left adrenal adenoma elucidated by adrenal vein sampling: A case report with in-depth physiological review on utility of aldosterone renin ratio

In cases of primary hyperaldosteronism, the aldosterone renin ratio (ARR) is crucial for determining the need for adrenal vein sampling (AVS). Our case highlights the importance of utilizing ARR with AVS, contextual interpretation of plasma renin and aldosterone levels, and stresses that sole reliance on imaging without AVS may result in unnecessary or contralateral adrenalectomy.

A 120-Minute Saline Infusion Test for the Confirmation of Primary Aldosteronism: A Pilot Study

BACKGROUND

The saline infusion test (SIT) to confirm primary aldosteronism requires infusing 2 L of normal saline over 240 minutes. Previous studies raised concerns regarding increased blood pressure and worsening hypokalemia during SIT. We aimed to evaluate the diagnostic applicability of a SIT that requires 1 L of saline infusion over 120 minutes.

METHODS

A cross-sectional study, including all patients in a large medical center who underwent SIT from 1 January 2015 to 30 April 2023. Blood samples were drawn for baseline renin and aldosterone (t = 0) after 2 hours (t = 120 min) and after 4 hours (t = 240 min) of saline infusion. We used ROC analysis to evaluate the sensitivity and specificity of various aldosterone cut-off values at t = 120 to confirm primary aldosteronism.

RESULTS

The final analysis included 62 patients. A ROC analysis yielded 97% specificity and 90% sensitivity for a plasma aldosterone concentration (PAC) of 397 pmol/L (14 ng/dL) at t = 120 to confirm primary aldosteronism, and an area under the curve of 0.97 (95% CI [0.93, 1.00], P < 0.001). Almost half (44%) of the patients did not suppress PAC below 397 pmol/L (14 ng/dL) at t = 120. Of them, only one (4%) patient suppressed PAC below 276 pmol/L (10 ng/dL) at t = 240. Mean systolic blood pressure increased from 140.1 ± 21.3 mm Hg at t = 0 to 147.6 ± 14.5 mm Hg at t = 240 (P = 0.011).

CONCLUSIONS

A PAC of 397 pmol/L (14 ng/dL) at t = 120 has high sensitivity and specificity for primary aldosteronism confirmation.

Using plasma aldosterone concentrations at 1 h of saline infusion test for the diagnosis of primary aldosteronism

OBJECTIVE

Saline infusion test (SIT) requires 2 l of isotonic saline for intravenous infusion over 4 h to suppress plasma aldosterone concentration (PAC). To shorten the procedure time and minimize the volume load, we study the performance of SIT at 1, 2 and 4 h for diagnosing primary aldosteronism.

METHODS

This is a cross-sectional study. PAC was measured before and 1, 2 and 4 h after saline infusion at a rate of 500 ml/h in patients suspected to have primary aldosteronism. Primary aldosteronism was diagnosed based on 4 h PAC, adrenal imaging and/or adrenal venous sampling (AVS).

RESULTS

Of the 93 patients, 32 had primary aldosteronism. The area under the receiver operating characteristic (ROC) curve of the 1, 2 and 4 h PAC were not statistically different. All of the nonprimary aldosteronism group had a 1 h PAC lower than 15 ng/dl and all of the primary aldosteronism group had a 1 h PAC higher than 5 ng/dl. Nearly 30% of the nonprimary aldosteronism and primary aldosteronism groups had a 1 h PAC between 5 and 15 ng/dl (equivocal range) and could be discriminated by using percentage suppression of 1 h PAC from baseline. Using 1 h PAC of more than 15 ng/dl together with percentage suppression of 1 h PAC from baseline of less than 60 when 1 h PAC was 5-15 ng/dl, primary aldosteronism could be detected with a sensitivity of 93.7% and specificity of 96.7%.

CONCLUSION

The 1 h SIT has a similar diagnostic performance to the standard SIT. Using 1 h PAC together with percentage suppression from baseline when 1 h PAC is equivocal, primary aldosteronism can be diagnosed with good accuracy.

A Novel ARMC5 Germline Variant in Primary Macronodular Adrenal Hyperplasia Using Whole-Exome Sequencing

Background: Primary macronodular adrenocortical hyperplasia (PMAH) is a rare form of adrenal Cushing’s syndrome with incomplete penetrance which may be sporadic or autosomal dominant. The inactivation of the ARMC5 gene, a potential tumor suppressor gene, is one of the associated causes of PMAH. This study aimed to identify the variant responsible for Iranian familial PMAH. Methods: The proband, a 44-year-old woman, was directed to whole-exome sequencing (WES) of the blood sample to discover a germline variant. In addition, the identified causative variant was confirmed and segregated in other and available unaffected family members. Results: The novel germline heterozygous missense variant, c.2105C>A in the ARMC5 gene, was found, and the same germline variant as the proband was confirmed in two affected sisters. This variant was detected in the brother of the proband with an asymptomatic condition and this considered because of incomplete penetrance and age-dependent appearance. The function of the ARMC5 protein would be damaged by the identified variant, according to in silico and computer analyses that followed. Conclusion: The new germline ARMC5 variation (c.2105C>A, (p. Ala702Glu)) was interpreted as a likely pathogenic variant based on ACMG and Sherloc standards. PMAH may be diagnosed early using genetic testing that shows inherited autosomal dominant mutations in the ARMC5 gene.

Performance of Confirmatory Tests for Diagnosing Primary Aldosteronism: a Systematic Review and Meta-Analysis

Background:

Confirmatory tests are recommended for diagnosing primary aldosteronism, but the supporting evidence is unclear.

Methods:

We searched Medline, EMBASE, and the Cochrane Central Register of Controlled Trials. Studies evaluating any guideline-recommended confirmatory test (ie, saline infusion test, salt loading test, fludrocortisone suppression test, and captopril challenge test), compared with a reference standard were included. The Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to assess the risk of bias. Meta-analyses were conducted using hierarchical summary receiver operating characteristic models.

Results:

Fifty-five studies were included, comprising 26 studies (3654 participants) for the recumbent saline infusion test, 4 studies (633 participants) for the seated saline infusion test, 2 studies (99 participants) for the salt loading test, 7 studies (386 participants) for the fludrocortisone suppression test, and 25 studies (2585 participants) for the captopril challenge test. Risk of bias was high, affecting more than half of studies, and across all domains. Studies with case-control sampling overestimated accuracy by 7-fold (relative diagnostic odds ratio, 7.26 [95% CI, 2.46–21.43]) and partial verification or use of inconsistent reference standards overestimated accuracy by 5-fold (5.12 [95% CI, 1.48–17.77]). There were large variations in how confirmatory tests were conducted, interpreted, and verified. Under most scenarios, confirmatory testing resulted in an excess of missed cases. The certainty of evidence underlying each test (Grading of Recommendations, Assessment, Development, and Evaluations) was very low.

Conclusions:

Recommendations for confirmatory testing in patients with abnormal screening tests and high probability features of primary aldosteronism are based on very low-quality evidence and their routine use should be reconsidered.

Primary Hyperaldosteronism: Approach to Diagnosis and Management

Hyperaldosteronism is a relatively more common disorder than previously recognized. Patients with hyperaldosteronism are at high risk for cardiovascular events. Patients suspected of having hyperaldosteronism should undergo initial screening and subsequent confirmatory testing to establish a biochemical diagnosis. Although adrenal computed tomography/magnetic resonance imaging scans often define a disease's subtype, adrenal vein sampling, in order to determine lateralization, may be necessary in some patients who are surgical candidates. Medical therapy using optimal doses of mineralocorticoid receptor antagonists can control symptoms and normalize plasma renin activity. The long-term outcome of patients treated with either surgical or optimal medical therapy appears similar.

Minor Change of Plasma Renin Activity during the Saline Infusion Test Provide an Auxiliary Diagnostic Value for Primary Aldosteronism

OBJECTIVE

To clarify whether it has some hidden diagnostic values for PA, especially in the case of an inconclusive SIT result, we investigated the difference in changes of plasma renin activity (PRA) during SIT between patients with PA and non-PA.

METHODS

We measured and compared the SIT parameters of 159 PA patients, 368 non-PA patients, and 43 inconclusive patients who were included in this study.

RESULTS

The PA group showed a minor change of PRA during the SIT (ΔPRA, defined as (pre-SIT PRA-post-SIT PRA)) compared with the non-PA group (0.17 ng/ml/h vs. 1.07 ng/ml/h, P < 0.001). According to ROC analysis, ΔPRA showed a greater AUC than post-SIT PRA (0.897 vs. 0.855, P < 0.001). The cutoff value was 0.5 ng/ml/h, with 90.3% sensitivity and 78.6% specificity. When combined with ARR post-SIT, it showed 81.6% sensitivity and 97.0% specificity for PA diagnosis. Further analysis of 43 patients with an inconclusive SIT result who completed AVS found that ΔPRA was smaller in the confirmed PA group compared with the unconfirmed PA group (0.19 ng/ml/h vs. 0.29 ng/ml/h, P < 0.05); there was no significant difference in PAC post-SIT between two groups. ΔPRA ≤ 0.21 ng/ml/h provides 71.4% sensitivity, 80.0% specificity, and 87.0% PPV for their PA diagnosis.

CONCLUSIONS

PA patients show minor PRA change during SIT; the change of PRA during SIT provides an auxiliary diagnostic value for PA, especially in patients with an inconclusive SIT result.

Comparison of the shortened and standard saline infusion tests for primary aldosteronism diagnostics

The saline infusion test (SIT) is widely used to confirm PA, but some patients may not tolerate the standard loading volume of 2 L saline over 4 h. The shortened SIT, loading only 1 L saline over 2 h, is suggested to be useful and would be more acceptable if the diagnostic utility of the shortened SIT is comparable to that of the standard SIT. We compared the diagnostic values of the plasma aldosterone concentration after 2 h of 1 L saline loading (2 h PAC) and that after 4 h of 2 L saline loading (4 h PAC) for the prediction of unilateral aldosterone hypersecretion and postoperative outcome. This retrospective, single-center study involved 555 PA-suspected patients who underwent SIT, 153 patients with adrenal vein sampling (AVS) results, and 37 patients with a 1-year postoperative evaluation. To detect the Japanese cutoff of 4 h PAC > 60 pg/mL, a 2-h PAC Youden Index at 66 pg/mL showed 91% sensitivity and 75% specificity. For unilateral aldosterone hypersecretion, the sensitivity and specificity of 2 h PAC were not inferior to those of 4 h PAC by Markov chain Monte Carlo (MCMC) methods. The sensitivity and specificity of 2 h PAC for postoperative reduction of anti-hypertensive drugs were also not inferior to those of 4 h PAC. Although using the 2 h PAC > 66 pg/mL cutoff may increase false positives for PA diagnosis, the shortened SIT, possibly using a cutoff value higher than 66 pg/mL, may be as useful as the standard SIT for selecting PA patients for AVS and to predict postoperative outcomes with reduced burden on patients.

Primary Aldosteronism: JACC State-of-the-Art Review

Primary aldosteronism (PA) is a common, but frequently overlooked, cause of arterial hypertension and excess cardiovascular events, particularly atrial fibrillation. As timely diagnosis and treatment can provide a cure of hyperaldosteronism and hypertension, even when the latter is resistant to drug treatment, strategies to screen patients for PA early with a simplified diagnostic algorithm are justified. They can be particularly beneficial in some subgroups of hypertensive patients, as those who are at highest cardiovascular risk. However, identification of the surgically curable cases of PA and achievement of optimal results require subtyping with adrenal vein sampling, which, as it is technically challenging and currently performed only in tertiary referral centers, represents the bottleneck in the work-up of PA. Measures aimed at improving the clinical use of adrenal vein sampling and at developing alternative techniques for subtyping, alongside recommendations for drug treatment, including new development in the field, and for follow-up are discussed.

The 2020 Italian Society of Arterial Hypertension (SIIA) practical guidelines for the management of primary aldosteronism

Background and aim

Considering the amount of novel knowledge generated in the last five years, a team of experienced hypertensionlogists was assembled to furnish updated clinical practice guidelines for the management of primary aldosteronism.

Methods

To identify the most relevant studies, the authors utilized a systematic literature review in international databases by applying the PICO strategy, and then they were required to make use of only those meeting predefined quality criteria. For studies of diagnostic tests, only those that fulfilled the Standards for Reporting of Diagnostic Accuracy recommendations were considered.

Results

Each section was jointly prepared by at least two co-authors, who provided Class of Recommendation and Level of Evidence following the American Heart Association methodology. The guidelines were sponsored by the Italian Society of Arterial Hypertension and underwent two rounds of revision, eventually reexamined by an External Committee. They were presented and thoroughly discussed in two face-to-face meetings with all co-authors and then presented on occasion of the 36th Italian Society of Arterial Hypertension meeting in order to gather further feedbacks by all members. The text amended according to these feedbacks was subjected to a further peer review.

Conclusions

After this process, substantial updated information was generated, which could simplify the diagnosis of primary aldosteronism and assist practicing physicians in optimizing treatment and follow-up of patients with one of the most common curable causes of arterial hypertension.

11 C-Metomidate PET/CT is a useful adjunct for lateralization of primary aldosteronism in routine clinical practice

OBJECTIVE

To describe clinical practice experience of ¹¹ C-Metomidate PET/CT as an adjunct to adrenal vein sampling (AVS) in the lateralization of aldosterone-producing adenomas (APA) in primary aldosteronism (PA).

CONTEXT

Accurate lateralization of APA in the setting of PA offers the potential for surgical cure and improved long-term cardiovascular outcomes. Challenges associated with AVS, the current gold standard lateralization modality, mean that only a small proportion of potentially eligible patients currently make it through to surgery. This has prompted consideration of alternative strategies for lateralization, including the application of novel molecular PET tracers such as ¹¹ C-Metomidate.

DESIGN

Clinical Service Evaluation/Retrospective audit.

PATIENTS

Fifteen individuals with a confirmed diagnosis of PA, undergoing lateralization with ¹¹ C-Metomidate PET/CT prior to final clinical decision on surgical vs medical management.

MEASUREMENTS

All patients underwent screening aldosterone renin ratio (ARR), followed by confirmatory testing with the seated saline infusion test, according to Endocrine Society Clinical Practice Guidelines. Adrenal glands were imaged using dedicated adrenal CT. ¹¹ C-Metomidate PET/CT was undertaken due to equivocal or failed AVS. Management outcomes were assessed by longitudinal measurement of blood pressure, ARR, number of hypertensive medications following adrenalectomy or institution of medical therapy.

RESULTS

We describe the individual lateralization and clinical outcomes for 15 patients with PA.

CONCLUSION

¹¹ C-Metomidate PET/CT in conjunction with adrenal CT and AVS provided useful information which aided clinical decision-making for PA within a multidisciplinary hypertension clinic.

Resistant Hypertension: Diagnosis and Management

Resistant hypertension is defined as high blood pressure requiring 3 or more medications for adequate control or controlled blood pressure requiring 4 or more medications. Considering the growing prevalence of hypertension and the strong link with cardiovascular disease, it is vital to understand the causes and treatment of resistant hypertension. This review article starts with an overview of the prevalence and little-known pathophysiology of resistant hypertension. Afterward, we discuss the evaluation and management of suspected secondary resistant hypertension in 2 broad categories: pseudoresistant hypertension and true resistant hypertension. Strategies for the identification and management of pseudoresistant hypertension are addressed. In addition, causes of true resistant hypertension, such as obstructive sleep apnea, primary aldosteronism, and renal artery stenosis, are examined along with their respective treatments. Finally, treatment of resistant hypertension is reviewed including pharmacologic treatments and novel procedural interventions for resistant hypertension. Overall, the review hopes to provide practitioners with a cohesive approach for the diagnosis and treatment of resistant hypertension.

MiR-193a-3p functions as a tumour suppressor in human aldosterone-producing adrenocortical adenoma by down-regulating CYP11B2

The mechanism of aldosterone-producing adrenocortical adenoma (APA) pathogenesis and the role of microRNAs (miRNAs) in APA pathogenesis have not been completely clarified. We examined the expression and function of miR-140-3p, miR-193a-3p and miR-22-3p, which have binding sites in CYP11B2. Expression of miRNAs and CYP11B2 mRNA was measured by quantitative reverse transcription PCR (qRT-PCR). Cell proliferation was monitored by colorimetric analysis, and cell apoptosis and cell cycle progression were analysed by flow cytometry. ELISA was carried out to detect aldosterone levels in cell culture supernatants. Luciferase reporter assays, qRT-PCR and Western blotting were performed to identify CYP11B2 as a target of miR-193a-3p. Of the three miRNAs examined, miR-193a-3p exhibited a significant decrease and CYP11B2 mRNA exhibited a significant increase in expression in APA compared with adjacent normal adrenal gland tissue. Transfection of miR-193a-3p mimic into the human adrenocortical cell line H295R showed that elevated miR-193a-3p expression inhibits proliferation and aldosterone secretion, induces G1-phase arrest and promotes apoptosis in H295R cells. Furthermore, in luciferase reporter assays, overexpression of miR-193a-3p in H295R cells significantly reduced the luciferase activity of the wild-type CYP11B2 3'-UTR construct, which could be reversed by mutation of the miR-193a-3p-binding site. Moreover, miR-193a-3p overexpression downregulated CYP11B2 mRNA and protein expression. Finally, overexpression of CYP11B2 diminished the effects of miR-193a-3p on H295R cells. Taken together, our results suggest that CYP11B2 levels may be modulated by miR-193a-3p in APA, which could explain, at least partially, why downregulation of miR-193a-3p during APA formation may promote cell growth and suppress apoptosis.

Cardiac magnetic resonance imaging of myocardial mass and fibrosis in primary aldosteronism

BACKGROUND

Primary aldosteronism (PA) is associated with increased cardiovascular morbidity, presumably due to left ventricular (LV) hypertrophy and fibrosis. However, the degree of fibrosis has not been extensively studied. Cardiac magnetic resonance imaging (CMR) contrast enhancement and novel sensitive T1 mapping to estimate increased extracellular volume (ECV) are available to measure the extent of fibrosis.

OBJECTIVES

To assess LV mass and fibrosis before and after treatment of PA using CMR with contrast enhancement and T1 mapping.

METHODS

Fifteen patients with newly diagnosed PA (PA1) and 24 age- and sex-matched healthy subjects (HS) were studied by CMR with contrast enhancement. Repeated imaging with a new scanner with T1 mapping was performed in 14 of the PA1 and 20 of the HS median 18 months after specific PA treatment and in additional 16 newly diagnosed PA patients (PA2).

RESULTS

PA1 had higher baseline LV mass index than HS (69 (53-91) vs 51 (40-72) g/m²; P < 0.001), which decreased significantly after treatment (58 (40-86) g/m²; P < 0.001 vs baseline), more with adrenalectomy (n = 8; -9 g/m²; P = 0.003) than with medical treatment (n = 6; -5 g/m²; P = 0.075). No baseline difference was found in contrast enhancement between PA1 and HS. T1 mapping showed no increase in ECV as a myocardial fibrosis marker in PA. Moreover, ECV was lower in the untreated PA2 than HS 10 min post-contrast, and in both PA groups compared with HS 20 min post-contrast.

CONCLUSION

Specific treatment rapidly reduced LV mass in PA. Increased myocardial fibrosis was not found and may not represent a common clinical problem.

Evaluation of the Saline Infusion Test and the Captopril Challenge Test in Chinese Patients With Primary Aldosteronism

CONTEXT

The aim of this study was to determine whether the diagnosis cutoff values associated with the saline infusion test (SIT) and captopril challenge test (CCT) in the Endocrine Society guidelines are applicable to Chinese subjects.

OBJECTIVE AND DESIGN

We performed a head-to-head comparison of the SIT and CCT among Chinese subjects with primary aldosteronism (PA) and essential hypertension (EH).

PARTICIPANTS AND SETTING

One hundred sixty-four hypertensive patients were enrolled.

INTERVENTION

All participants underwent both the SIT and CCT.

MAIN OUTCOME MEASURES

The plasma aldosterone concentration (PAC) and plasma renin activity were measured before and after the SIT and CCT. The degree of PAC decline after CCT was calculated.

RESULTS

This study included 115 PA and 49 EH subjects. The prevalence of hypokalemia was 74.8% in the PA group. Supine PACs in the EH and PA groups were 15.1 ± 4.7 mmol/L and 30.4 ± 12.1 mmol/L. Post-SIT PACs were 8.8 ± 1.7 ng/dL and 22.7 ± 10.2 ng/dL in the EH and PA groups. The degree of PAC decline after CCT was 17.7% and 14.2% in the EH and PA groups; post-CCT PACs were 11.7 ± 3.3 ng/dL and 25.9 ± 10.6 ng/dL. PAC values of 11.2 ng/dL and 16.7 ng/dL after the SIT and CCT represented the optimal cutoff values for PA diagnosis. The post-SIT and post-CCT area under the receiver operating characteristic curve values were 0.972 [95% confidence interval (CI) = 0.934 to 0.991] and 0.933 (95% CI = 0.883 to 0.966).

CONCLUSIONS

Post-SIT and post-CCT PACs, but not the degree of PAC suppression, were both reliable for PA diagnosis. However, the optimal cutoffs were slightly higher in Chinese subjects than those recommended by the Endocrine Society.

Increased urinary excretion of the epithelial Na channel activator prostasin in patients with primary aldosteronism

OBJECTIVES

Prostasin is a glycosylphosphatidylinositol-anchored serine protease that is released in urine and is involved in epithelial Na channel activation. A direct association between urinary prostasin (u-prostasin) concentration and activation of the aldosterone-driven pathway has been suggested; however, in previous studies on primary aldosteronism, a semiquantitative evaluation, rather than a precise quantification, of prostasin was performed. We aim to investigate if u-prostasin concentrations are higher in patients with primary aldosteronism than in patients with essential hypertension and whether u-prostasin measurements could be a useful marker for diagnosing primary aldosteronism in hypertensive patients.

METHODS

A total of 62 primary aldosteronism and 56 essential hypertension patients were enrolled. Biochemical and hormonal parameters were measured by applying routine laboratory methods, and u-prostasin levels were assessed by ELISA.

RESULTS

Primary aldosteronism patients had higher u-prostasin levels than did essential hypertension patients. Prostasin levels were positively correlated with the aldosterone-to-renin ratio and inversely correlated with plasma K and urinary Na levels. In the highest concentration quartile, u-prostasin levels were associated with a several-fold higher probability of primary aldosteronism diagnosis in hypertensive patients. Receiver operating characteristic curve analysis showed that prostasin was specific but poorly sensitive as a diagnostic marker for primary aldosteronism.

CONCLUSIONS

The study shows that an elevated u-prostasin concentration in humans is a specific marker for primary aldosteronism, which involves the classical model of epithelial Na channel activation. There was no statistically significant difference in prostasin concentrations among patients with different primary aldosteronism subtypes. Studies with a larger series of patients are necessary to clarify the clinical usefulness of the prostasin assay.

Saline Infusion Test highly associated with the incidence of cardio- and cerebrovascular events in primary aldosteronism

Primary aldosteronism (PA) is caused by excess secretion of aldosterone and is an independent risk factor for cardio-cerebro-vascular (CCV) events. The goal of treatment of PA should include prevention of CCV events. A definitive diagnosis of PA is established by confirmatory tests [saline infusion test (SIT), furosemide upright test (FUT) and captopril challenge test (CCT)]. However, there is no information on whether the hormone levels measured by these confirmatory tests are associated with CCV events. The aim of this retrospective study was to elucidate the relationship between the results of the above confirmatory tests and prevalence of CCV disease in patients with PA. The study subjects were 292 PA patients who were assessed for past history of CCV events at the time of diagnosis of PA. CCV events were significantly higher in patients with positive than negative SIT (12.8% vs. 3.3%, p=0.04). There were no differences in the incidences of CCV events between patients with positive and negative CCT and FUT (CCT: 11.0% vs. 3.9%, p=0.13, FUT: 6.1% vs. 5.7%, p=0.93). Our results demonstrated a higher incidence of CCV disease in PA SIT-positive patients compared to those with negative test. SIT is a potentially useful test not only for the diagnosis of PA but also assessment of the risk of CCV events.

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.

Primary Aldosteronism: Diagnosis and Management

Primary aldosteronism (PA) is an important and commonly unrecognized cause of secondary hypertension. Idiopathic hyperaldosteronism and aldosterone-producing adenomas account for more than 95% of PA and are characterized, respectively, by bilateral or unilateral involvement of the adrenal glands. When there is suspicion for the presence of PA, a plasma aldosterone to renin ratio should be obtained initially. Localization to determine adrenal gland involvement is done by imaging, with computerized tomography or magnetic resonance imaging. After imaging, adrenal vein sampling is done to establish treatment options. Patients with unilateral disease, who are good surgical candidates, are most appropriately managed with adrenalectomy. A biochemical cure is almost certain following adrenalectomy; however, only 30-50% of patients would show adequate blood pressure improvement. Patients with bilateral adrenal disease and those believed not to be surgical candidates are managed with mineralocorticoid antagonists.

SFE/SFHTA/AFCE consensus on primary aldosteronism, part 3: Confirmatory testing

Aldosterone/renin ratio (ARR) identifies patients at high or low risk of primary aldosteronism (PA), but sensitivity and especially specificity are suboptimal and confirmatory testing may therefore be necessary, in some but not all patients. In patients with elevated ARR and plasma aldosterone concentration above 550pmol/L (20ng/dL) on two assessments, PA can be diagnosed without confirmatory testing. Conversely, PA can be ruled out without confirmatory testing in patients with normal ARR and plasma aldosterone concentration below 240pmol/L (9ng/dL) on two assessments. In patients not corresponding to either of the previous conditions, dynamic confirmatory testing is mandatory. Several tests are available, based on aldosterone suppression by saline loading, fludrocortisone administration or converting enzyme inhibition by captopril. One test is based on renin stimulation by furosemide administration. Each of these tests has its limitations, and validation is incomplete. We recommend aldosterone suppression by saline infusion test. Renin stimulation by captopril may be used if sodium loading is contraindicated by impaired cardiac function.

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.

A NEW CLINICAL PREDICTION CRITERION ACCURATELY DETERMINES A SUBSET OF PATIENTS WITH BILATERAL PRIMARY ALDOSTERONISM BEFORE ADRENAL VENOUS SAMPLING

OBJECTIVE

Adrenal venous sampling (AVS) is the only available method to distinguish bilateral from unilateral primary aldosteronism (PA). AVS has several drawbacks, so it is reasonable to avoid this procedure when the results would not affect clinical management. Our objective was to identify a clinical criterion that can reliably predict nonlateralized AVS as a surrogate for bilateral PA that is not treated surgically.

METHODS

A retrospective diagnostic cross-sectional study conducted at Slovenian national endocrine referral center included 69 consecutive patients (mean age 56 ± 8 years, 21 females) with PA who underwent AVS. PA was confirmed with the saline infusion test (SIT). AVS was performed sequentially during continuous adrenocorticotrophic hormone (ACTH) infusion. The main outcome measures were variables associated with nonlateralized AVS to derive a clinical prediction rule.

RESULTS

Sixty-seven (97%) patients had a successful AVS and were included in the statistical analysis. A total of 39 (58%) patients had nonlateralized AVS. The combined criterion of serum potassium ≥3.5 mmol/L, post-SIT aldosterone <18 ng/dL, and either no or bilateral tumor found on computed tomography (CT) imaging had perfect estimated specificity (and thus 100% positive predictive value) for bilateral PA, saving an estimated 16% of the patients (11/67) from unnecessary AVS. The best overall classification accuracy (50/67 = 75%) was achieved using the post-SIT aldosterone level <18 ng/dL alone, which yielded 74% sensitivity and 75% specificity for predicting nonlateralized AVS.

CONCLUSIONS

Our clinical prediction criterion appears to accurately determine a subset of patients with bilateral PA who could avoid unnecessary AVS and immediately commence with medical treatment.

Post-saline infusion test aldosterone levels indicate severity and outcome in primary aldosteronism

OBJECTIVE

The saline infusion test (SIT) is widely used as a confirmatory test for primary aldosteronism (PA). SIT results are judged as follows: post-test aldosterone levels <50 ng/l exclude PA, whereas levels >50 ng/l confirm PA. We hypothesized that post-SIT aldosterone concentrations indicate the severity of PA and might predict outcome.

DESIGN

The study includes 256 PA patients of the German Conn's Registry who prospectively underwent SIT. The data of 126 patients with complete follow-up of 1.2±0.3 years after diagnosis were analyzed. The patients were divided into two groups with post-SIT aldosterone levels of 50-100 ng/l (group 1; n=38) and of >100 ng/l (group 2; n=88).

RESULTS

Patients in group 2 had a significantly shorter duration of hypertension (7.5 vs 11.7 years (median), P=0.014), higher systolic blood pressure (BP; 151±16 vs 143±17 mmHg, P=0.036), lower serum potassium (3.3±0.6 vs 3.5±0.4 mmol/l, P=0.006), higher 24-h urine protein excretion (7.4 vs 5.4 mg/dl (median), P=0.012), and were more often female (P=0.038). They showed more often unilateral disease (P<0.005) with larger tumors (14±10 vs 7±10 mm, P=0.021), underwent more often adrenalectomy (75% vs 37%, P<0.005), required a lower number of antihypertensive drugs after adrenalectomy (1.2±1.2 vs 2.5±1.4, P=0.001), had a faster normalization of urinary protein excretion (with medical treatment P=0.049; with Adx P<0.005) at follow-up, and more frequently underlying well-characterized mutation (P=0.047).

CONCLUSIONS

PA patients with post-SIT aldosterone levels of >100 ng/l have a more rapid development of PA caused more frequently by unilateral disease with larger aldosterone-producing adenomas. However, this group of patients may have a significantly better outcome following specific treatment.

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.

Long-term effects of adrenalectomy or spironolactone on blood pressure control and regression of left ventricle hypertrophy in patients with primary aldosteronism

INTRODUCTION

Primary aldosteronism (PA) represents the most common cause of secondary hypertension. Beyond increased blood pressure, additional harmful effects of aldosterone excess including inappropriate left ventricle (LV) hypertrophy were found. We evaluated the effect of adrenalectomy and spironolactone on blood pressure and myocardial remodelling in a long-term follow-up study.

METHODS

Thirty-one patients with PA were recruited. Fifteen patients with confirmed aldosterone-producing adenoma underwent adrenalectomy; in the remaining 16 patients, treatment with spironolactone was initiated. Laboratory data, 24-hour ambulatory blood pressure monitoring (ABPM) and echocardiography parameters were evaluated at baseline and at a median follow-up of 64 months.

RESULTS

Both approaches reduced blood pressure (p = 0.001 vs. baseline). In both groups we observed a decrease in end-diastolic (p = 0.04, p = 0.01) and end-systolic LV cavity diameters (p = 0.03, p = 0.01). Interventricular septum and posterior wall thickness reduction was significant only after adrenalectomy (p = 0.01, p = 0.03) as was reduction of LV mass index (p = 0.004). A trend to lower LV mass on spironolactone was caused predominantly by diminution of the LV cavity, which was reflected in increased relative wall thickness (p = 0.05).

CONCLUSIONS

Although both surgical and conservative treatment can induce a long-term decrease of blood pressure, adrenalectomy seems to be more effective in reduction of LV mass, as it reverses both wall thickening and enlargement of the LV cavity.

Seated saline suppression testing for the diagnosis of primary aldosteronism: a preliminary study

CONTEXT

Failure of aldosterone suppression by sodium loading during fludrocortisone suppression testing (FST) or saline suppression testing (SST) confirms primary aldosteronism (PA). We previously found recumbent SST (RSST) to lack sensitivity. Aldosterone levels can be higher upright (e.g. seated) than recumbent in patients with PA and upright levels are used during FST. We therefore hypothesized that seated SST (SSST) is more sensitive than RSST, especially for posture-responsive PA.

SETTING AND DESIGN

Of 66 patients who underwent FST (upright plasma aldosterone levels measured at 10am basally and after 4 days fludrocortisone 0.1 mg 6-hourly and oral salt loading), 31 underwent SST (aldosterone levels measured basally at 8am and after infusion of 2 L normal saline over 4h) both recumbent and seated in randomized order and at least 2 weeks apart.

RESULTS

FST confirmed PA in 23 of 31 patients (day 4 upright aldosterone level >165 pmol/L), excluded PA in three and was originally "inconclusive" in five. However, one with "inconclusive" FST had PA confirmed by lateralizing AVS and was reclassified "unilateral PA". Of 24 with confirmed PA (eight unilateral, 11 bilateral, and five undetermined subtype), 23 (96%) tested positive by SSST (4-h aldosterone level >165 pmol/L) compared with 8 (33%) by RSST (4-h plasma aldosterone level >140 pmol/L) (P < .001). RSST missed one unilateral, all bilateral, and four with as-yet undetermined subtype. RSST was positive in 7 of 10 (70%) posture-unresponsive vs one of 14 (7.1%) posture-responsive patients (P < .005).

CONCLUSION

These preliminary results suggest that seated SST may be superior to recumbent SST in terms of sensitivity for detecting PA, especially posture-responsive forms, and may represent a reliable alternative to FST.

NT-proBNP, a useful tool in hypertensive patients undergoing a diagnostic evaluation for primary aldosteronism

Primary aldosteronism (PA) is the most frequent form of secondary hypertension, but diagnostic tools for this disease still lack optimal accuracy. The heart is one important target tissue for damage due to excess aldosterone, and the role of natriuretic peptides is well recognized in diagnosing heart failure. We hypothesized that measuring the NT-proBNP could improve the diagnostic evaluation of PA. We enrolled 132 hypertensive patients, who underwent aldosterone to renin ratio (ARR) screening, and 81 underwent an intravenous saline loading test (ivSLT) because of a high ARR. The NT-proBNP level positively correlated with the ARR and inversely correlated with the renin level. The NT-proBNP level was higher in patients with a high ARR than in those with a low ARR and higher in patients with a positive ivSLT than in those with a negative ivSLT. After logistic regression analysis, an NT-proBNP value above the median and male gender were predictors of a positive ivSLT. The proportion of patients with a positive ivSLT ranged from only 23 % in females with a low NT-proBNP to 93 % in males with a high NT-proBNP. NT-proBNP and gender are predictors of a positive PA confirmatory test. These findings highlight the possibility of using NT-proBNP to identify which patients with a high ARR should receive a complete PA diagnostic evaluation.

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.

Diagnosis and treatment of primary aldosteronism

A few simple rules can allow physicians to successfully identify many patients with arterial hypertension caused by PA among the so-called essential hypertensive patients. The hyperaldosteronism and the hypokalemia can be cured with adrenalectomy in practically all of these patients. Moreover, in a substantial proportion of them, the blood pressure can be normalized or markedly lowered if a unilateral cause of PA is discovered. Hence, the screening for PA can be rewarding both for the patient and for the clinician, particularly in those cases where hypertension is severe and/or resistant to treatment, in which the removal of an APA can allow blood pressure to be brought under control despite withdrawal of, or a prominent reduction in, the number and doses of antihypertensive medications.

A comprehensive review of the clinical aspects of primary aldosteronism

Primary aldosteronism is much more common than previously thought. The high prevalence of primary aldosteronism, the damage this condition does to the heart, blood vessels and kidneys (which causes a high rate of cardiovascular events), along with the notion that a timely diagnosis followed by an appropriate therapy can correct the arterial hypertension and hypokalemia, justify efforts to search for primary aldosteronism in many patients with hypertension. Most centers can use a cost-effective strategy to screen for patients with primary aldosteronism. By contrast, the identification of primary aldosteronism subtypes, which involves adrenal-vein sampling, should only be undertaken at tertiary referral centers that have experience in performing and interpreting this test. The identification of a curable form of primary aldosteronism can be beneficial for the patient. In some subgroups of patients with hypertension who are at high risk of primary aldosteronism or can benefit most from an accurate diagnosis, an aggressive diagnostic approach is necessary.

Diagnosis and treatment of primary aldosteronism

Primary aldosteronism involves more than 11% of hypertensive patients who are referred to specialized centers for the diagnosis and treatment of hypertension. If not diagnosed early it causes an excess damage to the heart, vessels and kidney, which translates into an cardiovascular events. Since these ominous consequences can be corrected with a timely diagnosis and an appropriate therapy, physicians should exercise a high degree of alert concerning the possibility that primary aldosteronism is present in hypertensive patients. The purpose of this review is to provide up-dated information on the strategy for case detection, the subtype differentiation and the management of primary aldosteronism.

Association of DNA polymorphisms within the CYP11B2/CYP11B1 locus and postoperative hypertension risk in the patients with aldosterone-producing adenomas

OBJECTIVES

Hypertension often persists after adrenalectomy for primary aldosteronism. Traditional factors associated with postoperative hypertension were evaluated, but whether genetic determinants were involved remains poorly understood. The aim of this study was to investigate the association of DNA polymorphisms within steroid synthesis genes (CYP11B2, CYP11B1) and the postoperative resolution of hypertension in Chinese patients undergoing adrenalectomy for aldosterone-producing adenomas (APA).

METHODS

Ninety-three patients with APA were assessed for postoperative resolution of hypertension. All patients were genotyped for rs1799998 (C-344 T), intron 2 conversion, rs4539 (A2718G) within CYP11B2 and rs6410 (G22 5A), rs6387 (A2803G) within CYP11B1. The associations between CYPB11B2/CYP11B1 polymorphisms and persistent postoperative hypertension were assessed by multivariate analysis.

RESULTS

CYP11B2-CYP11B1 haplotype was associated with persistent postoperative hypertension in Chinese patients undergoing adrenalectomy with APA (P = .006). Specifically, the rs4539 (AA) polymorphism was associated with persistent postoperative hypertension (P = .002). Multivariate logistic regression revealed the common haplotypes H1 (AGACT), H2 (AGAWT), and H3 (AGAWC) were associated with the persistent postoperative hypertension (P = .01, 0.03, 0.005 after Bonferroni correction). Additional predictors of persistent postoperative hypertension included duration of hypertension (P <.0005), family history of hypertension (P = .001), and elevated systolic blood pressure (P = .015).

CONCLUSIONS

The rs4539 (AA), H1, H2, and H3 are genetic predictors for postoperative persistence of hypertension for Chinese patients treated by adrenalectomy with APA. DNA polymorphisms at CYP11B2/B1 locus may confer susceptibility to postoperative hypertension of patients with APA.

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.

Primary aldosteronism: an update

Primary aldosteronism (PA) is common with an estimated prevalence rate of 10% in subjects with essential hypertension and higher in those with resistant hypertension. As well as contributing to hypertension, aldosterone has detrimental effects on the heart, vasculature and kidneys as well as adverse metabolic effects leading to an excess of cardiovascular morbidity. Therefore, recognition and appropriate treatment of PA is of increasing importance. However, the diagnosis of PA and determination of subtype can be problematic. The purpose of this review is to provide an overview of the evidence supporting this increased prevalence of PA, explore the metabolic and cardiovascular consequences of aldosterone excess and discuss optimal diagnostic and therapeutic strategies of PA.

Polymorphisms in CYP11B2 and CYP11B1 genes associated with primary hyperaldosteronism

Several frequent polymorphisms in the CYP11B2 gene are suggested to be associated with essential hypertension and aldosterone secretion. In this study, we investigated the association of polymorphisms in CYP11B2 and CYP11B1 genes with the risk of primary hyperaldosteronism (PH). Three polymorphisms in the CYP11B2 gene (intron 2 conversion, rs1799998 and rs4539) and two polymorphisms in the CYP11B1 gene (rs6410 and rs6387) were analyzed in patients with PH and in the normal population. The rs6410 allelic frequencies in patients with aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA) were significantly different from those in controls at P=1.09 x 10(-5) and 0.015, respectively. There was a relative excess of AA homozygotes and AG heterozygotes of the rs6410 allele in the APA group as compared with the control group (P=2.19 x 10(-4)). There were significantly different genotypes, AA and AG, of the rs6410 allele between the patients with IHA and the controls only after adjustments for age, gender and body mass index (odds ratio (OR)=4.06, 95% confidence interval (CI) 1.31-12.66; OR=2.41, 95% CI 1.02-5.72). One susceptible haplotype, AAAWT, was identified to be significantly associated with APA (OR=1.44, 95% CI 1.19-1.76), and three susceptible haplotypes, AAAWT, AGGWT and AGAWC, were identified to be significantly associated with IHA (OR=1.55, 95% CI 1.23-1.96; OR=1.49, 95% CI 1.17-1.89; OR=1.40, 95% CI 1.04-1.88). In contrast, one protective haplotype, GGAWT, showed a significant difference between the patients with APA and controls (OR=0.73, 95% CI 0.55-0.97). Several haplotypes were associated with ARR in both the controls and cases. Our data demonstrated that there was a significant association between polymorphisms in the CYP11B2 and CYP11B1 genes and a genetic predisposition to PH. The association with IHA seemed closer compared with APA.

Primary aldosteronism: diagnostic accuracy of the losartan and captopril tests

BACKGROUND

To assess whether angiotensin-II receptor blockers (ARBs) offer any additional advantage in confirming the diagnosis of primary aldosteronism (PA) and their use in the differentiation of PA subtypes.

METHODS

A prospective, cohort, head-to-head study was conducted between July 2003 and July 2006. A total of 135 patients received captopril and losartan tests to confirm the diagnosis of PA in the TAIPAI (Taiwan Primary Aldosteronism Investigation) intervention.

RESULTS

In total, 71 patients were diagnosed with PA. The area under the receiver-operating characteristic (ROC) curve of the postcaptopril plasma aldosterone concentration (PAC) was significantly less than that of the postlosartan PAC (0.744 vs. 0.829, P = 0.038). Using an aldosterone-renin ratio (ARR, ng/dl per ng/ml/h) >35 with a PAC >10 ng/dl, the specificity was 89.1% vs. 93.8% and the sensitivity was 66.2% vs. 84.5 % for the captopril test vs. the losartan test, respectively. With respect to the losartan test, the accuracy was 88.9%, the agreement was good (k = 0.778), and there was no disagreement with the McNemar test (P = 0.118). Losartan had the advantage of a better negative predictive value to exclude PA when patients were referred with a serum potassium (SK) level <3.8 mmol/l. When a postlosartan ARR >60 was the cutoff value, the positive predictive value was 82% with a negative predictive value of 57% in distinguishing aldosterone-producing adenomas (APAs) from idiopathic hyperaldosteronism (IHA).

CONCLUSIONS

The postlosartan ARR and PAC were shown to have better accuracy for the diagnosis of PA than the captopril test. With a postlosartan ARR >60, APAs can be adequately differentiated from IHA.

A possible association between aldosterone response to vasopressin and circadian change of aldosterone in the patients with aldosterone-producing adenoma

Vasopressin was reported to stimulate secretion of both cortisol and aldosterone through eutopic V1a receptors in adrenal gland. Recently, adrenal hyper-responsiveness of plasma cortisol to vasopressin with eutopic overexpession of V1a receptors has been reported in Cushing's syndrome, such as a majority of cases of ACTH-independent macronodular adrenal hyperplasia and some cases of Cushing's adenomas. There were a few reports regarding the aldosterone response to vasopressin in aldosterone-producing adenoma. The aim of our study was to investigate the aldosterone response to vasopressin and its pathophysiological roles in the patients with aldosterone-producing adenoma. Vasopressin-loading test was performed in 10 patients with aldosterone-producing adenoma, and in 16 patients with non-functioning adrenal tumors. The roles of the aldosterone response to vasopressin were analyzed in terms of hormonal secretion and the expression of V1a receptor mRNA on the operated adrenal gland in aldosterone-producing adenoma. We found that (1) a varying aldosterone response to vasopressin was observed, (2) absolute response of plasma aldosterone in aldosterone-producing adenoma was significantly higher than that in non-functioning tumor, (3) aldosterone response rate to vasopressin was significantly and negatively correlated with the decline rate (%) in plasma aldosterone from morning to evening in aldosterone-producing adenoma, (4) V1a receptor mRNA was expressed at various values in aldosterone-producing adenoma, and (5) surgical removal of aldosterone-producing adenoma eliminated the aldosterone response to vasopressin observed in patients with aldosterone-producing adenoma. These findings indicated that vasopressin might be involved in the coordination of aldosterone secretion through eutopic expression of V1a receptor in aldosterone-producing adenoma.

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.

Inappropriate Left Ventricular Mass in Patients With Primary Aldosteronism

Assessment of appropriateness of left ventricular mass (LVM) for a given workload may better stratify hypertensive patients. Inappropriate LVM may reflect the interaction of genetic and neurohumoral factors other than blood pressure playing a significant role in myocardial growth. Primary aldosteronism (PA) represents a clinical model useful in assessing the effect of aldosterone increase on LVM. The aim of this study was to evaluate the inappropriateness of LVM in patients with PA. In 125 patients with PA (54 females; adrenal hyperplasia in 73 and adenoma in 52 patients) and in 125 age-, sex-, and blood pressure–matched, essential hypertensive patients, echocardiography was performed. The appropriateness of LVM was calculated by the ratio of observed LVM to the predicted value using a reference equation. In all of the subjects plasma renin activity and aldosterone, as well as clinic and 24-hour blood pressure, were measured. The prevalence of inappropriate LVM was greater in patients with traditionally defined left ventricular hypertrophy (70% and 44%, respectively; P =0.02) but also in patients without left ventricular hypertrophy (17% and 9%, respectively; P =0.085). In PA patients, a correlation was observed between the ratio of observed:predicted LVM and the ratio of aldosterone:plasma renin activity levels ( r =0.29; P =0.003) or the postinfusion aldosterone concentration ( r =0.44; P =0.004; n=42). In conclusion, in patients with PA, the prevalence of inappropriate LVM is increased, even in the absence of traditionally defined left ventricular hypertrophy. The increase in aldosterone levels could contribute to the increase of LV mass exceeding the amount needed to compensate hemodynamic load.