Primary aldosteronism: A needle in a haystack or a yellow cab on fifth avenue?

Characteristics and Outcomes in Primary Aldosteronism Patients Harboring Glucocorticoid-Remediable Aldosteronism

The clinical characteristics and surgical prognosis of glucocorticoid-remediable aldosteronism (GRA, also known as familial hyperaldosteronism type 1, FH-I) have not been widely studied. Using data from the Taiwan Primary Aldosteronism Investigation (TAIPAI) registry retrospectively, we describe the associated clinical factors for GRA and clinical predictors of surgical outcomes among identified GRA patients. We found 79 GRA-positive (51.2 ± 13.8 years; women 39 (49.4%)) and 114 GRA-negative primary aldosteronism (PA) patients matched with age, gender, and body mass index. Lower plasma aldosterone concentrations (PACs) and aldosterone-renin ratios were found among GRA-positive individuals. Multivariable logistic regression demonstrated that a PAC ≤ 40 ng/dL could predict concealed GRA individuals (OR 0.523, p = 0.037). Low serum potassium (OR 0.285, p = 0.008), but not the presence of GRA, was associated with hypertension-remission. Of note, PRA (OR 11.645, p = 0.045) and hypokalemia (OR 0.133, p = 0.048) were associated with hypertension-remission in GRA patients. Unilateral primary aldosteronism patients harboring concomitant GRA were not associated with inferior hypertension-remission after an adrenalectomy. Low serum potassium and high PRA were positively associated with hypertension-remission in GRA patients.

Therapeutic Outcomes with Surgical and Medical Management of Primary Aldosteronism

PURPOSE OF REVIEW

Primary aldosteronism (PA) is the most common cause of secondary hypertension and is significantly under-diagnosed. Delays in diagnosis and treatment can lead to cardiovascular morbidity and mortality. The goal of this study is to review the management of PA, with a focus on medical and surgical treatment outcomes.

RECENT FINDINGS

PA causes cardiovascular dysfunction in excess of degree of hypertension. Adrenalectomy demonstrates a therapeutic advantage over mineralocorticoid antagonist (MRA) therapy, after controlling for degree of hypertension and subtype of PA. Higher rates of atrial fibrillation, heart failure, stroke, and incidence of chronic kidney disease are observed in subjects treated with MRAs than in subjects treated with adrenalectomy. The therapeutic benefit of surgery may reflect definitive resolution of excess aldosterone. Complete mineralocorticoid blockade may achieve similar benefit to adrenalectomy. Adrenalectomy is the most effective treatment for unilateral PA. Biomarkers for MRA therapy might inform optimal medical therapy of bilateral adrenal hyperplasia.

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.

Mineralocorticoid Receptor and Aldosterone-Related Biomarkers of End-Organ Damage in Cardiometabolic Disease

The mineralocorticoid receptor (MR) was first identified as a blood pressure regulator, modulating renal sodium handling in response to its principal ligand aldosterone. The mineralocorticoid receptor is also expressed in many tissues other than the kidney, such as adipose tissue, heart and vasculature. Recent studies have shown that MR plays a relevant role in the control of cardiovascular and metabolic function, as well as in adipogenesis. Dysregulation of aldosterone/MR signaling represents an important cause of disease as high plasma levels of aldosterone are associated with hypertension, obesity and increased cardiovascular risk. Aldosterone displays powerful vascular effects and acts as a potent pro-fibrotic agent in cardiovascular remodeling. Mineralocorticoid receptor activation regulates genes involved in vascular and cardiac fibrosis, calcification and inflammation. This review focuses on the role of novel potential biomarkers related to aldosterone/MR system that could help identify cardiovascular and metabolic detrimental conditions, as a result of altered MR activation. Specifically, we discuss: (1) how MR signaling regulates the number and function of different subpopulations of circulating and intra-tissue immune cells; (2) the role of aldosterone/MR system in mediating cardiometabolic diseases induced by obesity; and (3) the role of several MR downstream molecules as novel potential biomarkers of cardiometabolic diseases, end-organ damage and rehabilitation outcome.

Sleep quality in patients with primary aldosteronism

OBJECTIVE

In subjects at high risk for sleep apnea (SA), aldosterone concentrations correlate with severity of SA and primary aldosteronism (PA) is very often diagnosed. Patients with PA show a high prevalence of SA. Treatment of PA either by adrenalectomy (ADX) or mineralocorticoid receptor (MR) blockade is thought to abolish the increased comorbidities. However, no data are available regarding effectiveness of different PA treatments on quality of sleep.

DESIGN

This prospective multi-center study included 15 patients with newly diagnosed PA evaluated before and 0.7 ± 0.2 years after treatment initiation, and a second cohort including 81 patients who were evaluated 5.3 and 6.8 years after treatment initiation. Biochemical parameters, 24h blood pressure and three validated self-assessment questionnaires (Giessen Complaint List (GBB-24), Epworth Sleepiness Scale (ESS) and Pittsburgh Sleep Quality-Index (PSQI)) were analyzed.

RESULTS

Z-scores of exhaustion tendency of GBB significantly improved in newly diagnosed PA patients after treatment initiation (1.8 ± 1.4 vs. 1.0 ± 1.2, p=0.034). In the second cohort no differences were found in GBB-24, ESS and PSQI. No differences were found in all three questionnaires independently of type of PA therapy. However, female patients scored significantly higher than males in the PSQI (8.7 ± 3.6 vs 5.7 ± 4.2, p<0.005), indicating lower sleep quality, independently of the type of therapy.

CONCLUSIONS

For the first time, we analyzed quality of sleep in patients with PA, demonstrating that therapy initiation improves exhaustion tendency. Surprisingly, female PA patients showed significantly more sleep disturbances than male PA patients several years after treatment initiation.

Bimodal aldosterone distribution in low-renin hypertension

BACKGROUND

In low-renin hypertension (LRH), serum aldosterone levels are higher in those subjects with primary aldosteronism and may be lower in those with non-aldosterone mineralocorticoid excess or primary renal sodium retention. We investigated the hypothesis that the frequency distribution of aldosterone in LRH is bimodal.

METHODS

Of the 3,532 attendees at the sixth examination cycle of the Framingham Offspring Study, 1,831 were included in this cross-sectional analysis after we excluded those with conditions or taking medications such as antihypertensive drugs that might affect renin or aldosterone.

RESULTS

Three hundred three subjects (17%) had untreated hypertension (SBP ≥140 mm Hg or DBP ≥90 mm Hg). LRH, defined as plasma renin ≤5 mU/L, was present in 93 of those 303 hypertensive subjects (31%). Aldosterone values were adjusted statistically for age, sex, and the urinary sodium/creatinine ratio. In the subjects with LRH, the adjusted aldosterone distribution was bimodal (dip test for unimodality, P = 0.008). The adjusted aldosterone distribution was unimodal in the normal subjects (P = 0.98) and in the hypertensive subjects with normal plasma renin (P = 0.94).

CONCLUSIONS

In this community-based sample of white subjects, those with low-renin hypertension had a bimodal adjusted aldosterone distribution. Subjects with normal-renin hypertension and subjects with normal blood pressure had unimodal adjusted aldosterone distributions. These findings suggest 2 pathophysiological variants of LRH, one that is aldosterone-dependent and one that is non-aldosterone-dependent.

Effectiveness of eplerenone or spironolactone treatment in preserving renal function in primary aldosteronism

OBJECTIVE

Primary aldosteronism (PA) has deleterious effects on kidney function independent of blood pressure levels. Up to now, data on effectiveness of different PA therapies regarding renal function are scarce.

DESIGN AND METHODS

This prospective multi-center study included 29 patients with newly diagnosed PA evaluated before and 1 year after treatment initiation, and a second cohort including 119 patients who were evaluated 5.3 and 6.8 years after treatment initiation. Glomerular filtration rate (GFR), spot urine albumin excretion/urinary creatinine (UAE/Ucrea) ratio, biochemical parameters, and 24-h blood pressure were measured. In a larger cross-sectional cohort, renal function was evaluated depending on the type of treatment (adrenalectomy (ADX; n=86); spironolactone (n=65); and eplerenone (n=18)).

RESULTS

GFR and UAE/Ucrea ratio significantly decreased in newly diagnosed PA patients after treatment initiation. In the second cohort, GFR and UAE/Ucrea ratio did not change during study period, and blood pressure was well controlled. In the larger cross-sectional cohort, no differences were seen in GFR and UAE/Ucrea ratio between PA patients on different treatment regimens. However, eplerenone treatment showed lower potassium levels and higher number of required antihypertensive medications.

CONCLUSIONS

Renal dysfunction with elevated albuminuria was seen in PA patients and was reversible after treatment initiation. Medical therapies with spironolactone or eplerenone seem to be as effective as ADX regarding renal function and blood pressure; however, sufficient daily doses need to be given.

Resistant hypertension and undiagnosed primary hyperaldosteronism detected by use of a computerized database

A pharmacy database was used to identify patients with resistant hypertension who could then be tested for the presence of primary hyperaldosteronism. Inclusion criteria were: (1) resistant hypertension defined as uncontrolled hypertension and use of 3 antihypertensive medication classes or ≥ 4 antihypertensive classes regardless of blood pressure; (2) low or normal potassium levels (≤ 4.9 mEq/L); and (3) continuous health care from October 1, 2008, to February 28, 2009. Exclusion criteria were: (1) past or current use of an aldosterone antagonist, or (2) a medication possession ratio (adherence) <80% for any antihypertensive drug. Hyperaldosteronism was classified as an aldosterone/renin ratio (ARR) ≥ 30. Using the computer, 746 patients were identified who met criteria. After manual chart review to verify inclusion and exclusion criteria, 333 patients remained. Of 184 individuals in whom an ARR was obtained, 39 (21.2%) had a ratio of ≥ 30. A computer database is useful to identify patients with resistant hypertension and those who may have primary aldosteronism.

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.

Predictors of resolution of hypertension after adrenalectomy in patients with aldosterone-producing adenoma

Primary aldosteronism (PA) is a frequent cause of secondary hypertension and is amenable to surgical intervention when it is caused by aldosterone-producing adenoma (APA). Many patients, however, continue to require antihypertensive medications to control their blood pressure after adrenalectomy. The aim of this study was to determine the preoperative factors that predict clinical outcomes after adrenalectomy in patients with APA. We studied 27 patients (mean age 45+/-4 yr) who had APA and underwent unilateral adrenalectomy between December 1995 and September 2008 at our institution. Clinical and biochemical data were evaluated at baseline and after a mean follow-up of 51.8+/-47.0 months (range, 6-159). At the end of the follow-up, 16 patients (59.3%) were considered to experience "complete resolution" without postoperative medications, whereas 7 patients (25.9%) "improved" with medications and 4 patients (14.8%) were "uncontrolled." Three factors (< or =2 antihypertensive medications [P=0.007], duration of hypertension <6 yr [P=0.002], and serum aldosterone <350 pg/mL [P<0.001]) were the predictive for complete resolution in univariate analysis. Multivariate regression analysis showed that serum aldosterone level (<350 pg/mL) was the single most important factor that predicted complete resolution after surgery (P<0.001). The best preoperative clinical factor that predicted resolution of postoperative hypertension after adrenalectomy is serum aldosterone level (<350 pg/mL).

[Primary hyperaldosteronisms: from diagnosis to treatment]

Primary hyperaldosteronism is a growing cause of apparently essential hypertension (until 15 % of patients with hypertension). Primary hyperaldosteronism can now be recognized even for patients without hypertension or hypokaliemia. Paradoxically normal levels of aldosterone when serum renin levels and/or plasmatic renin activity and/or kaliemia are low, lead to suggest primary hyperaldostéronism. High values of aldosterone/renin or aldosterone/PRA favour the diagnosis. Adrenal scanography (fine slices) has to be performed, and confronted with one functional procedure (adrenal iodocholestérol uptake after dexamethasone, or sampling of adrenal venous blood for aldosterone measurement) only if surgery is suggested. When hypersecretion is unilateral or largely predominant in one size, surgery is very useful, when hypertension or hypokaliemia are poorly controlled, when medications are unwell tolerated, especially in men.

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.

The aldosteronoma resolution score: predicting complete resolution of hypertension after adrenalectomy for aldosteronoma

OBJECTIVE

To develop a prediction model using information readily available, at clinical presentation, which could determine whether patients with aldosterone-producing adenomas would have complete resolution of hypertension after adrenalectomy.

BACKGROUND

Primary aldosteronism is the most common curable cause of secondary hypertension. However, a large number of patients continue to require antihypertensive medications to control their blood pressure. Differentiating patients that will have complete resolution of hypertension without the need for antihypertensive medications from patients that will require continued use of antihypertensive medications is difficult before adrenalectomy.

METHODS

The predictive logistic regression model was derived using data on 100 patients who underwent adrenalectomy for primary aldosteronism at one tertiary medical center and was externally validated using an independent series of 67 patients from another center.

RESULTS

Clinical features were similar for patients in the derivation and validation groups. Four readily available predictors (2 or fewer antihypertensive medications, body mass index < or =25 kg/m, duration of hypertension < or =6 years, and female sex) yielded the best predictive model for complete resolution of hypertension after adrenalectomy. Based on the resulting 4-item aldosteronoma resolution score (ARS), 3 likelihood levels for complete resolution were identified: low (0-1), medium (2-3), and high (4-5) with a predictive accuracy of 27%, 46%, and 75%, respectively.

CONCLUSION

The ARS accurately identifies individuals at low (ARS < or =1) or high (ARS > or =4) likelihood of complete resolution of hypertension without further need of lifelong antihypertensive medications after adrenalectomy for aldosteronoma. This scoring system can help clinicians objectively inform patients of likely clinical outcomes before surgical intervention.

Is adrenal venous sampling necessary in all patients with hyperaldosteronism before adrenalectomy?

PURPOSE

To evaluate whether selective rather than universal use of adrenal vein sampling (AVS) may be warranted in patients with hyperaldosteronism to characterize and lateralize disease before adrenalectomy.

MATERIALS AND METHODS

Fifty-nine consecutive patients with biochemically diagnosed hyperaldosteronism underwent unilateral adrenalectomy at a single center during a 10-year period. In one group (n = 30), adrenalectomy was based on computed tomography (CT) only; in another (n = 29), it was based on CT and AVS. The indication for AVS was equivocal CT finding (n = 26) or patient request (n = 3). Outcome variables were postoperative serum potassium and aldosterone levels, number of hypertensive medications, and mean arterial blood pressure at 6 months.

RESULTS

Preoperatively, both groups were matched for age, years of hypertension, mean arterial blood pressure, and number of hypertensive medications. Average tumor sizes were 2 cm (range, 1-3 cm) in the CT-only group and 1 cm (range, 0-2.5 cm) in the CT/AVS group. Unilateral tumor was identified on CT in 30 patients (100%) in the CT-only group and in 17 patients (59%) in the CT/AVS group (P < .05). Postoperatively, aldosterone levels were lower in the CT-only group (6.3 ng/dL +/- 5.9 vs 13.5 ng/dL +/- 16; P < .05). Both groups had similar improvements in mean arterial blood pressure at 6 months (92 mm Hg +/- 12 vs 96 mm Hg +/- 9; P = .14), reductions in number of hypertensive medications (to 1.1 +/- 1.3 vs 1.2 +/- 1.1; P = .4), and improvements in hypokalemia (3.8 mEq/L +/- 0.5 vs 3.8 mEq/L +/- 0.5; P = .5).

CONCLUSIONS

The clinical impact of adrenalectomy was similar in both groups. CT can be used to reliably diagnose adenomas larger than 1.0 cm. AVS should be used when CT findings are equivocal or both adrenal glands are abnormal.

Prospective evaluation of the saline infusion test for excluding primary aldosteronism due to aldosterone-producing adenoma

BACKGROUND

Data on the performance of the tests used to confirm the diagnosis of primary aldosteronism (PA) are limited.

OBJECTIVE

To prospectively investigate the accuracy of the saline infusion test (SIT).

METHODS

Three hundred and seventeen (26.9%) out of 1125 patients screened in the PAPY study underwent measurement of plasma aldosterone, cortisol and renin activity after infusion of 2 l of isotonic saline intravenously over 4 h. They comprised patients with a baseline aldosterone/renin ratio (ARR) > 40 and one every four patients not fulfilling such criterion. The area under the receiver-operator characteristic curves (AUC) of aldosterone values after SIT was used as a measure of accuracy for diagnosing PA, aldosterone-producing adenoma (APA) or idiopathic hyperaldosteronism (IHA).

RESULTS

One hundred and twenty (37.9%) patients had PA that was due to an APA in 46 (38.3%) and to IHA in 74 (61.7%). No untoward effect occurred with the SIT. The AUC (0.811 +/- 0.026, 0.878 +/- 0.040 and 0.784 +/- 0.034 for identification of PA, APA and IHA, respectively) was higher (P < 0.0001) than that under the diagonal. By sensitivity/specificity versus criterion values plot, the best aldosterone cut-off values for identifying APA and IHA were 6.75 and 6.91 ng/dl, respectively. However, even at these optimal cut-offs, sensitivity and specificity were moderate because of values overlapping between patients with and without the disease. Moreover, there were no differences of AUC and aldosterone cut-offs between APA and IHA.

CONCLUSION

In a multicenter study the SIT was safe and specific for excluding PA, but had no place for discriminating between an APA and IHA.

A prospective study of the prevalence of primary aldosteronism in 1,125 hypertensive patients

OBJECTIVES

We prospectively investigated the prevalence of curable forms of primary aldosteronism (PA) in newly diagnosed hypertensive patients.

BACKGROUND

The prevalence of curable forms of PA is currently unknown, although retrospective data suggest that it is not as low as commonly perceived.

METHODS

Consecutive hypertensive patients referred to 14 hypertension centers underwent a diagnostic protocol composed of measurement of Na+ and K+ in serum and 24-h urine, sitting plasma renin activity, and aldosterone at baseline and after 50 mg captopril. The patients with an aldosterone/renin ratio >40 at baseline, and/or >30 after captopril, and/or a probability of PA (by a logistic discriminant function) > or =50% underwent imaging tests and adrenal vein sampling (AVS) or adrenocortical scintigraphy to identify the underlying adrenal pathology. An aldosterone-producing adenoma (APA) was diagnosed in patients who in addition to excess autonomous aldosterone secretion showed: 1) lateralized aldosterone secretion at AVS or adrenocortical scintigraphy, 2) adenoma at surgery and pathology, and 3) a blood pressure decrease after adrenalectomy. Evidence of excess autonomous aldosterone secretion without such criteria led to a diagnosis of idiopathic hyperaldosteronism (IHA).

RESULTS

A total of 1,180 patients (age 46 +/- 12 years) were enrolled; a conclusive diagnosis was attained in 1,125 (95.3%). Of these, 54 (4.8%) had an APA and 72 (6.4%) had an IHA. There were more APA (62.5%) and fewer IHA cases (37.5%) at centers where AVS was available (p = 0.002); the opposite occurred where AVS was unavailable.

CONCLUSIONS

In newly diagnosed hypertensive patients referred to hypertension centers, the prevalence of APA is high (4.8%). The availability of AVS is essential for an accurate identification of the adrenocortical pathologies underlying PA.

Renal damage in primary aldosteronism: results of the PAPY Study

Primary aldosteronism (PA) has been associated with cardiovascular hypertrophy and fibrosis, in part independent of the blood pressure level, but deleterious effects on the kidneys are less clear. Likewise, it remains unknown if the kidney can be diversely involved in PA caused by aldosterone-producing adenoma (APA) and idiopathic hyperaldosteronism (IHA). Hence, in the Primary Aldosteronism Prevalence in Italy (PAPY) Study, a prospective survey of newly diagnosed consecutive patients referred to hypertension centers nationwide, we sought signs of renal damage in patients with PA and in comparable patients with primary hypertension (PH). Patients (n = 1180) underwent a predefined screening protocol followed by tests for confirming PA and identifying the underlying adrenocortical pathology. Renal damage was assessed by 24-hour urine albumin excretion (UAE) rate and glomerular filtration rate (GFR). UAE rate was measured in 490 patients; all had a normal GFR. Of them, 31 (6.4%) had APA, 33 (6.7%) had IHA, and the rest (86.9%) had PH. UAE rate was predicted (P < 0.001) by body mass index, age, urinary Na+ excretion, serum K+, and mean blood pressure. Covariate-adjusted UAE rate was significantly higher in APA and IHA than in PH patients; there were more patients with microalbuminuria in the APA and IHA than in the PH group (P = 0.007). Among the hypertensive patients with a preserved GFR, those with APA or IHA have a higher UAE rate than comparable PH patients. Thus, hypertension because of excess autonomous aldosterone secretion features an early and more prominent renal damage than PH.

Aldosterone breakthrough during ras blockade: A role for endothelins and their antagonists?

Activation of the renin-angiotensin system (RAS), with ensuing aldosterone excess, detrimentally affects outcome in patients with hypertension and heart failure (HF). RAS blockade with angiotensin (Ang) 1-converting enzyme inhibitors (ACEIs) or Ang II type 1 receptor blockers (ARBs) is beneficial in such conditions. However, aldosterone secretion can persist despite these treatments. Hence, mechanisms besides Ang II acquire the role of aldosterone secretagogue. The RALES and EPHESUS studies have shown that this aldosterone "escape" or "breakthrough" is an important factor, because it is a determinant of outcome in HF patients. Endothelin (ET)-1, which stimulates aldosterone secretion via both A (ETA) and B (ETB) receptor subtypes, and which is increased in HF, is a candidate for the "aldosterone breakthrough." Moreover, the novel ET peptide ET-1(1-31) is involved in adrenocortical growth. Therefore, findings suggesting a role for the ET-1 system as an aldosterone secretagogue, along with the potential usefulness of endothelin antagonists for the prevention of "aldosterone breakthrough," are discussed.

Dynamic testing with high-dose adrenocorticotrophic hormone does not improve lateralization of aldosterone oversecretion in primary aldosteronism patients

OBJECTIVE

Diagnosing aldosterone-producing adenoma (APA) involves a demonstration of the lateralization of aldosterone oversecretion because adrenal incidentalomas are common in hypertensive individuals and many small-sized APA escape identification with available imaging techniques. However, because of the pulsatile pattern of aldosterone secretion this can be a difficult undertaking. Stimulation of aldosterone secretion before adrenal vein sampling (AVS) can overcome this difficulty, but anecdotal data exist. We, therefore, prospectively investigated the usefulness of AVS with dynamic testing in primary aldosteronism (PA) patients.

METHODS

We enrolled 24 consecutive consenting patients with a biochemical diagnosis of PA from a tertiary referral centre to measure the effects of adrenocorticotrophic hormone (ACTH) on selectivity, the lateralization of aldosterone secretion to the APA side, and adverse effects. After correcting the hypokalemia we performed bilateral AVS. After 3 h supine resting, blood was simultaneously obtained from both sides. A high-dose ACTH (250 mug intravenous) bolus was then administered and AVS was repeated after 30 min.

RESULTS

AVS was bilaterally selective in 88% of patients; no adverse effects occurred. Of the 21 patients with bilaterally selective AVS, three had idiopathic hyperaldosteronism and 18 an APA that was surgically removed in 12 with an ensuing fall in blood pressure at follow-up. After ACTH patients showed a significant increase (P = 0.007) of aldosterone from contralateral adrenal vein blood, but not from the APA gland. Therefore, lateralization of aldosterone secretion on the APA side did not improve.

CONCLUSION

AVS is safe and accurate for identifying APA. However, at a statistical power of 99%, these results do not support the usefulness of high-dose ACTH testing to improve the diagnostic accuracy of AVS.