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

Disordered aldosterone-volume relationship in end-stage kidney disease

INTRODUCTION

Sodium loading, and subsequent volume expansion, suppresses aldosterone levels in individuals with normal renal function. We hypothesised that loss of renal function impairs this volume-aldosterone relationship.

MATERIALS AND METHODS

With multifrequency bioimpedance spectroscopy, we measured total body water (TBW), extracellular volume (ECV), and intracellular volume in five haemodialysis patients at varied states of hydration and in five healthy volunteers during low-, normal-, and high-salt diets. Serum aldosterone, potassium, and C-reactive protein were measured simultaneously. Scatterplots and general estimating equations were used to examine the relationship among these variables.

RESULTS

In healthy volunteers with salt loading, and in haemodialysis subjects with increased inter-dialytic weight gain, expansion of ECV led to reciprocal declines in serum aldosterone concentrations. The relationship was more profound in healthy volunteers (p<0.001) than in haemodialysis subjects (p=0.1). Notably, haemodialysis subjects posted consistently higher levels of ECV (median 49.6% TBW, IQR 43.9-51.8% compared to 41.1%, 39.9-42.8% in volunteers) and serum aldosterone (median 26.7 ng/dl, IQR 19.8-29.6 compared to 12.4 ng/dl, 8.8-16.0 in volunteers). Serum potassium did not appear to influence aldosterone concentration (p=0.9).

CONCLUSIONS

The shift of the volume-aldosterone curve in haemodialysis subjects suggests that end-stage kidney disease is a state of high volume and inappropriately high aldosterone. These data have important clinical implications, as dialysis patients may benefit from both volume reduction and mineralocorticoid receptor blockade.

Efficacy of spironolactone therapy in patients with true resistant hypertension

The role of spironolactone in resistant hypertension management is unclear. The aim of this prospective trial was to evaluate the antihypertensive effect of spironolactone in patients with true resistant hypertension diagnosed by ambulatory blood pressure monitoring. A total of 175 patients had clinical and complementary exams obtained at baseline and received spironolactone in doses of 25 to 100 mg/d. A second ambulatory blood pressure monitoring was performed after a median interval of 7 months. Paired Student t test was used to assess differences in blood pressure before and during spironolactone administration, and multivariate analysis adjusted for age, sex, and number of antihypertensive drugs to assess the predictors of blood pressure fall. There were mean reductions of 16 and 9 mm Hg, respectively, in 24-hour systolic and diastolic blood pressures (95% CIs: 13 to 18 and 7 to 10 mm Hg; P<0.001). Office systolic blood pressure and diastolic blood pressure also decreased (14 and 7 mm Hg). Controlled ambulatory blood pressure was reached in 48% of patients. Factors associated with better response were higher waist circumference, lower aortic pulse wave velocity, and lower serum potassium. No association with plasma aldosterone or aldosterone:renin ratio was found. Adverse effects were observed in 13 patients (7.4%). A third ambulatory blood pressure monitoring performed in 78 patients after a median of 15 months confirmed the persistence of the spironolactone effect. In conclusion, spironolactone administration to true resistant hypertensive patients is safe and effective in decreasing blood pressure, especially in those with abdominal obesity and lower arterial stiffness. Its addition to an antihypertensive regimen as the fourth or fifth drug is recommended.

Adrenal venous sampling for primary aldosteronism and clinical outcomes after unilateral adrenalectomy: a single-center experience

Adrenal venous sampling (AVS) remains controversial in the management of primary aldosteronism. Retrospective chart review was conducted at the Hospital of the University of Pennsylvania from July 2001 to September 2007. A total of 113 patients underwent AVS, 16 patients were excluded as records were unavailable. Among 97 remaining patients, 61 had unilateral disease and 57 underwent unilateral adrenalectomy. Blood pressure (BP) improved significantly with less antihypertensive medication requirement. Among those with different BP responses to adrenalectomy (cure, improvement, or no change), a higher number of preoperative antihypertensive medications was associated with persistent hypertension (P = .03). There were no significant differences in age (P = .14), duration of hypertension (P = .60), family history of hypertension (P = .68), or serum creatinine (P = .34). When AVS shows lateralization, age, duration of hypertension, family history, or renal dysfunction did not predict BP response to adrenalectomy. Results suggest that these factors should not preclude AVS and subsequent adrenalectomy. Further studies are indicated to confirm these findings.

Update in primary aldosteronism

It is now widely recognized that primary aldosteronism (PA) is much more common than previously thought, accounting for up to 5-10% of hypertensives, and that aldosterone excess has adverse cardiovascular consequences that go above and beyond hypertension development. These findings have precipitated a marked resurgence of research activity, most of which has supported the concept that PA plays an important role in cardiovascular disease states and should be systematically sought and specifically treated, and the development of an Endocrine Society clinical guideline for the case detection, diagnosis, and management of this common, specifically treatable, and potentially curable condition. Areas of recent, topical research include: 1) the demonstration of excess morbidity in patients with PA compared with other forms of hypertension, confirming the clinical relevance of non-blood pressure-dependent adverse effects of aldosterone excess; 2) the further demonstration that this excess morbidity and mortality are ameliorated with specific (but not nonspecific antihypertensive) therapy directed against aldosterone excess, confirming the importance of detection and diagnosis of PA to enable optimal specific management; 3) the development of new treatment strategies; 4) an ongoing appraisal and refinement of diagnostic approaches including screening, subtype differentiation, and new assay development; and 5) further insights into the importance and nature of genetic factors related to the development of PA.

Adrenal venous sampling: where is the aldosterone disappearing to?

Adrenal venous sampling (AVS) is generally considered to be the gold standard in distinguishing unilateral and bilateral aldosterone hypersecretion in primary hyperaldosteronism. However, during AVS, we noticed a considerable variability in aldosterone concentrations among samples thought to have come from the right adrenal glands. Some aldosterone concentrations in these samples were even lower than in samples from the inferior vena cava. We hypothesized that the samples with low aldosterone levels were unintentionally taken not from the right adrenal gland, but from hepatic veins. Therefore, we sought to analyze the impact of unintentional cannulation of hepatic veins on AVS. Thirty consecutive patients referred for AVS were enrolled. Hepatic vein sampling was implemented in our standardized AVS protocol. The data were collected and analyzed prospectively. AVS was successful in 27 patients (90%), and hepatic vein cannulation was successful in all procedures performed. Cortisol concentrations were not significantly different between the hepatic vein and inferior vena cava samples, but aldosterone concentrations from hepatic venous blood (median, 17 pmol/l; range, 40–860 pmol/l) were markedly lower than in samples from the inferior vena cava (median, 860 pmol/l; range, 460–4510 pmol/l). The observed difference was statistically significant (P < 0.001). Aldosterone concentrations in the hepatic veins are significantly lower than in venous blood taken from the inferior vena cava. This finding is important for AVS because hepatic veins can easily be mistaken for adrenal veins as a result of their close anatomic proximity.

131I-6beta-iodomethyl-19-norcholesterol SPECT/CT for primary aldosteronism patients with inconclusive adrenal venous sampling and CT results

The 2 main causes of primary aldosteronism (PA) are aldosterone-producing adenoma (APA) and idiopathic adrenal hyperplasia (IAH). Dexamethasone-suppression (131)I-6beta-iodomethyl-19-norcholesterol (NP-59) adrenal scintigraphy can assess the functioning of the adrenal cortex. This study evaluated the diagnostic usefulness of NP-59 SPECT/CT in differentiating APA from IAH and in predicting postadrenalectomy clinical outcome for PA patients who had inconclusive adrenal venous sampling (AVS) and CT results.

METHODS

We retrospectively reviewed the 31 adrenal lesions of 27 patients (age range, 33-71 y; mean age +/- SD, 50.4 +/- 10.9 y) who had been clinically confirmed (by saline infusion and captopril tests) to have PA, had inconclusive CT and AVS test results, and had undergone NP-59 imaging before adrenalectomy. The accuracy of NP-59 imaging was determined by comparison with histopathologic findings.

RESULTS

NP-59 SPECT/CT gave us 18 true-positive, 3 false-positive, 6 true-negative, and 4 false-negative results. Compared with planar imaging, SPECT/CT significantly improved diagnostic accuracy and prognostic predicting ability (P = 0.0390 and P = 0.0141, respectively). The NP-59 results were negative for 7 of the 23 patients with unilateral adrenal lesions, and none of these 7 patients had shown postsurgical clinical improvement.

CONCLUSION

NP-59 SPECT/CT is an effective imaging tool for differentiating APA from IAH in PA patients whose CT and AVS results are inconclusive. Our results suggest that patients with presurgically negative NP-59 results should be treated medically and that noninvasive NP-59 SPECT/CT may be suited for use as the first lateralization modality after CT in patients with clinically confirmed PA.

Diagnosis of diseases of steroid hormone production, metabolism and action

Biochemical tests have been the basis for investigations of disorders affecting steroid hormones. In recent years it has been possible however to study the genes that determine functional enzymes, cofactors, receptors, transcription factors and signaling systems that are involved in the process. Analyses of mutations are available as a diagnostic service for only a few of these genes although research laboratories may be able to provide a service. Both biochemical and genetic research have brought to light new disorders. Some genes for transcription factors involved in the development of the endocrine organs have also been identified and patients with defects in these processes have been found. This paper will review general aspects of adrenal disorders with emphasis on clinical and laboratory findings. As with all endocrine investigations there are few single measurements that provide a definitive answer to a diagnosis. Timing of samples in relation to age, gender and time of day needs to be considered.

Management of endocrine manifestations and the use of mitotane as a chemotherapeutic agent for adrenocortical carcinoma

Adrenal cortical carcinoma (ACC) is a rare malignancy in which patients have poor overall 5-year survival. Patients with ACC can present with symptoms of hormone excess, including Cushing's syndrome, virilization, feminization, or--less frequently--hypertension with hypokalemia. In many patients with ACC, advanced disease at presentation precludes surgery or is followed by local relapse or distant metastatic disease that cannot be managed surgically. In these instances, chemotherapy is often tried, but its limited efficacy all too often leaves the problem of persistent hormonal excess. Physicians who treat patients with ACC and severe hypercortisolism should recognize that uncontrolled hormone production is a malignant disease, which has severe consequences that require aggressive management. Because chemotherapy benefits only a small percentage of patients, steroidogenesis inhibitors, including mitotane, ketoconazole, metyrapone, and etomidate, should be used singly or in combination even as chemotherapy is administered. Diligent management with frequent adjustments is required, especially in patients with chemotherapy-refractory tumors that continue to grow. In the absence of randomized, controlled trials, adjuvant use of mitotane remains controversial, although the authors of a recent case-control study argue for its use. Despite difficulty administering effective doses, most clinicians agree that mitotane should be used if the tumor cannot be removed surgically or should be used as adjuvant therapy if there is a high likelihood of recurrence. The option of long-term monotherapy is restricted to patients who tolerate mitotane and either experience a clinical response or are at high risk for recurrence. Recommendations are provided to help manage patients with this difficult disease and to improve the quality of their lives.

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 reverse postural test as a screening tool for aldosterone-producing adenoma: a pilot study

The aldosterone-to-renin ratio (ARR) is an accepted screening tool for primary hyperaldosteronism (PA). An ambulatory case finding test to separate surgically remediable aldosterone-producing adenoma (APA) from other forms of PA, however, is currently not available. The aim of this study was to evaluate a reverse postural test (RPT) as a novel tool for identifying APA. We investigated 6 healthy controls, 19 primary hypertensive patients, and a prospective cohort of 32 patients clinically suspicious for primary hyperaldosteronism. We diagnosed seven patients with surgically proven APA, and three patients with idiopathic hyperaldosteronism. Serum aldosterone was measured after 30-min of moderate exercise (Aldo-1) and after a subsequent 2-h supine resting period (Aldo-2) with calculation of the ratio Aldo-2/Aldo-1. Aldosterone significantly decreased after supine resting in both healthy controls and primary hypertensives, but not in patients with APA. Receiver-operating-curve analysis revealed that the RPT was suitable for the screening of APA. A combination of the ratio Aldo-2/Aldo-1 >0.59 and Aldo-2 >160 pg/ml correctly identified all the patients with APA, with no false positives. Although the high sensitivity of the RPT here observed needs to be confirmed in larger studies, the high positive predictive value of RPT could be useful for the identification of APA in outpatients.

Association of kidney function with residual hypertension after treatment of aldosterone-producing adenoma

BACKGROUND

Autonomous secretion of aldosterone in patients with primary aldosteronism increases glomerular filtration rate and causes kidney damage. The influence of a mild decrease in kidney function on residual hypertension after adrenalectomy is unexplored.

STUDY DESIGN

Nonconcurrent prospective study.

SETTING & PARTICIPANTS

The study was based on the Taiwan Primary Aldosteronism Investigation (TAIPAI) database. 150 patients (61 men; overall mean age, 47.2 +/- 11.6 years) with a diagnosis of aldosterone-producing adenoma had undergone unilateral adrenalectomy at National Taiwan University Hospital from July 1999 to January 2007.

PREDICTOR

Presurgery estimated glomerular filtration rate (eGFR).

OUTCOMES & MEASUREMENTS

Residual hypertension after adrenalectomy, defined either as less than 75% of recorded blood pressure measurements with systolic blood pressure less than 140 mm Hg and diastolic blood pressure less than 90 mm Hg or requiring antihypertensive medications during the first year after surgery.

RESULTS

Before surgery, 27 (18%), 72 (48%), and 51 (34%) patients had moderately to severely decreased (<60 mL/min/1.73 m(2)), mildly decreased (60 <or= eGFR < 90 mL/min/1.73 m(2)), or nondecreased eGFR (>or=90 mL/min/1.73 m(2)), respectively. After surgery, 16 (59.3%), 29 (40.3%), and 10 (19.3%) patients in each category had postsurgery residual hypertension. Compared with patients without decreased eGFR before surgery, adjusted odds ratios for postsurgery residual hypertension were 2.7 (95% confidence interval, 1.03 to 7.0; P = 0.04) and 2.8 (95% confidence interval, 1.05 to 9.3) for mildly and moderately to severely decreased eGFR, respectively.

LIMITATIONS

Arbitrary definition for residual hypertension.

CONCLUSIONS

Two-thirds of patients with aldosterone-producing adenoma were cured of hypertension by means of unilateral adrenalectomy. Kidney function impairment, even mild, appears to be associated with a high incidence of postsurgery residual hypertension.

Some considerations about evolution of idiopathic primary aldosteronism

The prevalence of primary aldosteronism has increased since many patients who were previously considered as being affected by low renin essential hypertension are actually satisfying the new diagnostic criteria using plasma aldosterone/ plasma renin activity (PRA) ratio. Many of these cases could be classified as subclinical hyperaldosteronism, having normal aldosterone and low PRA, or in alternative the normal range of aldosterone should be revised. Idiopathic hyperaldosteronism can, in many cases, be considered as an evolutive disease: it can be hypothesized that the biochemical picture can be preceded by essential hypertension and that, after several years, primary aldosteronism can evolve back to essential hypertension due to age-related reduced vascular and adrenal sensitivity to angiotensin II. This effect is also evident after longterm treatment with aldosterone receptors blockers and therefore it possible that aldosterone-receptors blockers are able to normalize the sensitivity of glomerulosa to angiotensin II even after long-term withdrawal. The use of aldosterone receptors blockers prevents cardiovascular complications due to local aldosterone effect at the level of endothelium and mononuclear leukocytes; therefore, these drugs should be also considered for therapy of patients with hypertension. It is not excluded that aldosterone receptor blockers could prevent the onset of idiopathic hyperaldosteronism and its complications in patients with hypertension without primary hyperaldosteronism. From all these considerations it follows that the concept of normal range of aldosterone should be revised and the use of aldosterone receptor blockers should be revisited.

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

OBJECTIVE

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

CONTEXT

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

DESIGN AND SETTING

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

RESULTS

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

CONCLUSION

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

Long-term effects of surgical correction of adrenal hyperplasia and adenoma causing primary aldosteronism

PURPOSE

The purpose of this is to study long-time results of surgery for primary aldosteronism.

MATERIALS AND METHODS

Thirty patients operated on for primary aldosteronism were followed for an average of 7 years. All but five required potassium substitution. Systolic as well as diastolic hypertension (mean 157/93 mmHg) was present necessitating one to five antihypertensive drugs daily (mean 2.33). Preoperative indications for surgery included presumed adenoma (aldosterone-producing adenoma (APA)) or in one case unilateral dominance of hyperplasia.

RESULTS

Histopathology was classified into adenoma (n = 9), dominant nodule (n = 16), and general hyperplasia without dominating nodules (n = 5), demonstrating a higher frequency of hyperplasia than anticipated. Long-term results revealed well-controlled blood pressure (BP; mean 134/80 mmHg). Antihypertensive medication was reduced (average of 1.78 per day), but only 36% of the patients were taken off these drugs completely. S-Aldosterone was normalized. All but one (a recurrence) were normokalemic without potassium substitution at follow-up. The APA group needed less medication (median 0.5 vs. 1.5 and 2 per day) and more patients in this group were totally medication free (50%). Two recurrences occurred in the group with general hyperplasia without dominating nodules.

CONCLUSION

Nodular hyperplasia is more common than anticipated. Hypersecretion of aldosterone may be released from a large nodule identified as an adenoma, as well as from a generally hyperplastic gland that has not been identified as such. Nevertheless, surgery for lateralized disease results in good long-term control of BP with less antihypertensive medication. However, patients with dominant nodule or general hyperplasia without dominating nodules need more postoperative treatment than patients with APA. The majority of patients do not achieve normotension without medications, but they do become normokalemic.

Guidelines for acromegaly management: an update

OBJECTIVE

The Acromegaly Consensus Group reconvened in November 2007 to update guidelines for acromegaly management.

PARTICIPANTS

The meeting participants comprised 68 pituitary specialists, including neurosurgeons and endocrinologists with extensive experience treating patients with acromegaly. EVIDENCE/CONSENSUS PROCESS: Goals of treatment and the appropriate imaging and biochemical and clinical monitoring of patients with acromegaly were enunciated, based on the available published evidence.

CONCLUSIONS

The group developed a consensus on the approach to managing acromegaly including appropriate roles for neurosurgery, medical therapy, and radiation therapy in the management of these patients.

Adrenocorticotropic Hormone Stimulation During Adrenal Vein Sampling for Identifying Surgically Curable Subtypes of Primary Aldosteronism

Adrenocorticotropic hormone administration was proposed to overcome the biases associated with pulsatile aldosterone secretion during adrenal venous sampling, but the usefulness of different protocols of stimulation was never systematically assessed. We, therefore, compared the effects of a high dose (HD; 250 μg IV as a bolus), a very low dose (VLD; 250 pg IV), and an intermediate dose (ID; 50 μg/h) of adrenocorticotropic hormone on the selectivity index (SI) and the lateralization index in primary aldosteronism patients, using the diagnosis of aldosterone-producing adenoma, based on pathology and follow-up data, as a reference. The HD (n=47) significantly increased plasma cortisol concentration in infrarenal inferior vena cava (+79%) blood and the SI on both sides (SI RIGHT +113% and SI LEFT +131%), as compared with baseline values. The ID (n=14) also markedly increased both plasma cortisol concentration inferior vena cava (+93%) and the SI (SI RIGHT +690% and SI LEFT +410%); the very low dose (n=6) had no effect on either the plasma cortisol concentration or SI. In the patients with unilateral aldosterone-producing adenoma, the increase of selectivity with the HD and ID was counterbalanced by a confounding effect on the correct identification of the aldosterone-producing adenoma side, which was attributed to the wrong side in 3.0% and 12.5% with HD and ID, respectively. In conclusion, the HD and the ID, but not the very low dose, adrenocorticotropic hormone stimulation protocol facilitated the ascertainment of selectivity of adrenal vein catheterization. However, this favorable effect was overridden by a confounding effect on the identification of lateralized aldosterone excess to the aldosterone-producing adenoma side. Hence, we do not recommend adrenocorticotropic hormone stimulation.

The diagnosis and treatment of primary hyperaldosteronism in Germany: results on 555 patients from the German Conn Registry

BACKGROUND

Primary hyperaldosteronism (Conn's syndrome) is being diagnosed increasingly often. As many as 12% of patients with hypertension have the characteristic laboratory constellation of Conn's syndrome. Its diagnosis and treatment have not been standardized.

METHODS

The authors retrospectively analyzed data of 555 patients (327 men and 228 women, aged 55 +/- 13 years) who were treated for primary hyperaldosteronism in 5 different centers from 1990 to 2006. The objective was to determine center-specific features of diagnosis and treatment.

RESULTS

353 (63%) of the patients had the hypokalemic variant of primary hyperaldosteronism; 202 never had documented hypokalemia. The centers differed markedly with respect to the patients' clinical presentation, diagnostic testing of endocrine function, and diagnostic imaging techniques, including adrenal venous sampling. The adrenalectomy rate ranged from 15% to 46%.

CONCLUSIONS

The registry data reveal an unexpected heterogeneity in the diagnostic evaluation and treatment of primary hyperaldosteronism. National or international guidelines are needed so that these can be standardized.

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

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

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

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

Graz Endocrine Causes of Hypertension (GECOH) study: a diagnostic accuracy study of aldosterone to active renin ratio in screening for primary aldosteronism

BACKGROUND

Primary aldosteronism (PA) affects approximately 5 to 10% of all patients with arterial hypertension and is associated with an excess rate of cardiovascular complications that can be significantly reduced by a targeted treatment. There exists a general consensus that the aldosterone to renin ratio should be used as a screening tool but valid data about the accuracy of the aldosterone to renin ratio in screening for PA are sparse. In the Graz endocrine causes of hypertension (GECOH) study we aim to prospectively evaluate diagnostic procedures for PA.

METHODS AND DESIGN

In this single center, diagnostic accuracy study we will enrol 400 patients that are routinely referred to our tertiary care center for screening for endocrine hypertension. We will determine the aldosterone to active renin ratio (AARR) as a screening test. In addition, all study participants will have a second determination of the AARR and will undergo a saline infusion test (SIT) as a confirmatory test. PA will be diagnosed in patients with at least one AARR of >or= 5.7 ng/dL/ng/L (including an aldosterone concentration of >or= 9 ng/dL) who have an aldosterone level of >or= 10 ng/dL after the saline infusion test. As a primary outcome we will calculate the receiver operating characteristic curve of the AARR in diagnosing PA. Secondary outcomes include the test characteristics of the saline infusion test involving a comparison with 24 hours urine aldosterone levels and the accuracy of the aldosterone to renin activity ratio in diagnosing PA. In addition we will evaluate whether the use of beta-blockers significantly alters the accuracy of the AARR and we will validate our laboratory methods for aldosterone and renin.

CONCLUSION

Screening for PA with subsequent targeted treatment is of great potential benefit for hypertensive patients. In the GECOH study we will evaluate a standardised procedure for screening and diagnosing of this disease.

Small tumor size as favorable prognostic factor after adrenalectomy in Conn's adenoma

OBJECTIVE

Primary aldosteronism (PA) due to aldosterone-producing adenoma (APA) is the most common curable form of secondary hypertension.

DESIGN

In order to evaluate blood pressure outcome after adrenalectomy for APA and to identify new favorable prognostic factors, data from 42 consecutive APA patients who underwent adrenalectomy were collected from 2005 to 2007.

METHODS

Renin-angiotensin-aldosterone system (upright and postsaline infusion test), serum and urinary electrolytes, office and ambulatory blood pressure monitoring were evaluated at baseline and after a follow-up of 2.7+/-2.2 years. Drug history and adenoma size at morphological evaluation were also collected.

RESULTS

Multiple regression analysis showed that, before surgery, patients with a small adenoma (diameter <20 mm) displayed higher postsaline aldosterone values (P=0.0001), and lower serum potassium levels (P=0.020), than patients with adenoma >20 mm. Before surgery, mineralocorticoid receptor (MR) antagonists were used in patients with small APA in greater percentage than patients with bigger adenomas (64 vs 30% respectively, P=0.037). At follow-up, blood pressure normalized in 63% of the subjects. Recovered patients had a shorter duration of hypertension (P=0.038), and a smaller adenoma size (P=0.035). Receiver operating characteristic curves showed that a duration of hypertension <or=6 years and an APA size <20 mm were the best predictors of blood pressure normalization. Patients with APA <20 mm showed the complete restoration of blood pressure circadian rhythm.

CONCLUSIONS

The presence of APA <20 mm, duration of hypertension equal or less than 6 years, and preoperative MR antagonists use are favorable prognostic factors for hypertension recovery after adrenalectomy.

Interaction of aldosterone and extracellular volume in the pathogenesis of obesity-associated kidney disease: a narrative review

Obesity and obesity-associated kidney injuries have played an important role in the rising prevalence of chronic kidney disease (CKD). The link between obesity and kidney disease begins with obesity's well-known associations with diabetes and hypertension, the two leading etiologies of CKD. However, a growing body of evidence suggests that elevated aldosterone levels and expanded extracellular volume are key components of obesity-induced renal disease via aldosterone's non-epithelial effects on the kidney. Highlighting these blood pressure- and diabetes-independent mechanisms of kidney injury in obesity allows an exploration of whether mineralocorticoid receptor blockade, coupled with weight loss and salt restriction, is an optimal treatment for overweight CKD patients.

Physiologic variance of corticotropin affects diagnosis in adrenal vein sampling

OBJECTIVE

Differentiating unilateral form from bilateral is a critical diagnostic step in primary aldosteronism (PA), for which adrenal vein sampling (AVS) is accepted to be the most reliable. However, variance of corticotropin could affect the diagnosis in AVS.

DESIGN AND METHODS

We conducted simultaneous bilateral AVS on ten biochemically diagnosed PA cases, and used the aldosterone-to-cortisol ratio (A/C) of the samples for the diagnosis. The diagnosis by AVS after a low-dose (0.1 microg) ACTH stimulation, which can provoke maximum-physiologic corticotropic response, was compared with those before the stimulation and after the standard-dose (250 microg) ACTH stimulation.

RESULTS

In half of the cases, the low-dose pre-stimulation affected the diagnosis. In four out of ten cases, the side-to-side ratios of A/C were changed in the basal/low-dose/standard-dose AVS as 6.62/2.46/0.63, 2.13/0.41/0.14, 1.88/2.38/2.40, and 1.96/2.27/1.90 respectively. In three out of ten cases, the adrenal vein to the matching inferior vena cava ratio of A/C was also changed across 1, the cut-off to indicate suppression of aldosterone secretion. Additionally, the confirmation of successful sampling was difficult in five out of ten and two out of ten cases of the basal and low-dose AVS respectively, whereas it was easy in all the cases of the standard-dose AVS.

CONCLUSIONS

The diagnosis in the basal AVS could be affected by the physiologic fluctuation of ACTH at relatively high prevalence. The basal AVS would be unreliable to differentiate two forms of PA.

The serum sodium to urinary sodium to (serum potassium)2 to urinary potassium (SUSPPUP) ratio in patients with primary aldosteronism

BACKGROUND

The aldosterone-to-renin ratio (ARR) is an established diagnostic tool in the screening for primary aldosteronism (PA). However, hormonal determinations are time consuming and expensive. Therefore, we studied the effectiveness of the serum sodium to urinary sodium to (serum potassium)(2) to urinary potassium (SUSPPUP) ratio in the diagnosis of PA.

DESIGN

This study included 35 patients with PA, 71 patients with essential hypertension to whom this diagnosis could be excluded, 23 normal subjects without hypertension, and 22 patients with primary adrenal insufficiency. We compared the SUSPPUP ratios with the ARR in these patient groups.

RESULTS

We show that the ARR distinguished PA from essential hypertension with a sensitivity of 94.2% and a specificity of 92.1% at a cutoff of 33 (ng L(-1): ng L(-1)). It correlated well with the SUSPPUP ratio. The sensitivity and specificity of SUSPPUP was 88.6% and 85.9% at a cutoff of 5.3 (mmol L(-1))(-1), respectively, and thus not as good as the ARR.

CONCLUSIONS

The ARR is a good parameter in the screening for PA. The SUSPPUP ratio is a cheap and rapid tool to assess the extent of mineralocorticoid excess and, therefore, can be offered to more patients. In addition, the application of the SUSPPUP ratio can be extended to patients who suffer from other forms of mineralocorticoid hypertension (e.g. with low aldosterone levels).

What are the keys to successful adrenal venous sampling (AVS) in patients with primary aldosteronism?

Adrenal venous sampling (AVS) is the criterion standard to distinguish between unilateral and bilateral adrenal disease in patients with primary aldosteronism. The keys to successful AVS include appropriate patient selection, careful patient preparation, focused technical expertise, defined protocol, and accurate data interpretation. The use of AVS should be based on patient preferences, patient age, clinical comorbidities, and the clinical probability of finding an aldosterone-producing adenoma. AVS is optimally performed in the fasting state in the morning. AVS is an intricate procedure because the right adrenal vein is small and may be difficult to locate - the success rate depends on the proficiency of the angiographer. The key factors that determine the successful catheterization of both adrenal veins are experience, dedication and repetition. With experience, and focusing the expertise to 1 or 2 radiologists at a referral centre, the AVS success rate can be as high as 96%. A centre-specific, written protocol is mandatory. The protocol should be developed by an interested group of endocrinologists, radiologists and laboratory personnel. Safeguards should be in place to prevent mislabelling of the blood tubes in the radiology suite and to prevent sample mix-up in the laboratory.