Forms Of Primary Aldosteronism Research Articles

Determination of 18-hydroxycortisol, 18-oxocortisol by HPLC-MS/MS in the differential diagnosis of various forms of primary aldosteronism

Determination of 18-hydroxycortisol, 18-oxocortisol by HPLC-MS/MS in the differential diagnosis of various forms of primary aldosteronism

Immunogenetics of primary hyperaldosteronism: fundamental studies and their clinical prospects

Primary hyperaldosteronism (PHA) is the most common form of endocrine hypertension. Until recently, the reason for the development of this condition was believed to be the presence of genetic mutations, however, many studies declare that the disease can be polyetiologic, be the result of genetic mutations and autoimmune triggers or cell clusters of aldosterone-producing cells diffusely located in the adrenal gland at the zona glonerulosa, zona fasculata, zona reticularis, as well as directly under the adrenal capsule. Recently, the actions of autoantibodies to type 1 angiotensin II receptors have been described in patients with renal transplant rejection, with preeclampsia, and with primary hyperaldosteronism. The diagnostic role of antibodies in both forms of PHA (aldosterone-producing adenoma and bilateral hyperaldosteronism) requires clarification. Diagnosis and confirmation of the focus of aldosterone hypersecretion is a multi-stage procedure that requires a long time and economic costs. The relevance of timely diagnosis of primary hyperaldosteronism is to reduce medical and social losses. This work summarizes the knowledge about genetic mutations and presents all the original studies devoted to autoantibodies in PHA, as well as discusses the diagnostic capabilities and limitations of the available methods of primary and differential diagnosis of the disease and the prospects for therapy.

Correction: Autonomous Aldosterone Secretion as a Subclinical Form of Primary Aldosteronism: Pathogenesis and Clinical Significance.

Correction: Autonomous Aldosterone Secretion as a Subclinical Form of Primary Aldosteronism: Pathogenesis and Clinical Significance.

Targeted RNAseq of Formalin-Fixed Paraffin-Embedded Tissue to Differentiate Among Benign and Malignant Adrenal Cortical Tumors.

Lack of routine fresh or frozen tissue is a barrier to widespread transcriptomic analysis of adrenal cortical tumors and an impediment to translational research in endocrinology and endocrine oncology. Our group has previously pioneered the use of targeted amplicon-based next-generation sequencing for archival formalin-fixed paraffin-embedded (FFPE) adrenal tissue specimens to characterize the spectrum of somatic mutations in various forms of primary aldosteronism. Herein, we developed and validated a novel 194-amplicon targeted next-generation RNA sequencing (RNAseq) assay for transcriptomic analysis of adrenal tumors using clinical-grade FFPE specimens. Targeted RNAseq-derived expression values for 27 adrenal cortical tumors, including aldosterone-producing adenomas (APA; n=8), cortisol-producing adenomas (CPA; n=11), and adrenal cortical carcinomas (ACC; n=8), highlighted known differentially-expressed genes (DEGs; i. e., CYP11B2, IGF2, etc.) and tumor type-specific transcriptional modules (i. e., high cell cycle/proliferation transcript expression in ACC, etc.), and a subset of DEGs was validated orthogonally using quantitative reverse transcription PCR (qRT-PCR). Finally, unsupervised hierarchical clustering using a subset of high-confidence DEGs revealed three discrete clusters representing APA, CPA, and ACC tumors with corresponding unique gene expression signatures, suggesting potential clinical utility for a transcriptomic-based approach to tumor classification. Overall, these data support the use of targeted amplicon-based RNAseq for comprehensive transcriptomic profiling of archival FFPE adrenal tumor material and indicate that this approach may facilitate important translational research opportunities for the study of these tumors.

Elevated aldosterone and blood pressure in a mouse model of familial hyperaldosteronism with ClC-2 mutation

Gain-of-function mutations in the chloride channel ClC-2 were recently described as a cause of familial hyperaldosteronism type II (FH-II). Here, we report the generation of a mouse model carrying a missense mutation homologous to the most common FH-II-associated CLCN2 mutation. In these Clcn2R180Q/+ mice, adrenal morphology is normal, but Cyp11b2 expression and plasma aldosterone levels are elevated. Male Clcn2R180Q/+ mice have increased aldosterone:renin ratios as well as elevated blood pressure levels. The counterpart knockout model (Clcn2−/−), in contrast, requires elevated renin levels to maintain normal aldosterone levels. Adrenal slices of Clcn2R180Q/+ mice show increased calcium oscillatory activity. Together, our work provides a knockin mouse model with a mild form of primary aldosteronism, likely due to increased chloride efflux and depolarization. We demonstrate a role of ClC-2 in normal aldosterone production beyond the observed pathophysiology.

The method of differential diagnosis of the main forms of primary hyperaldosteronism by high performance liquid chromatography

Objective.To provide a method of differential diagnosis of the main forms of primary hyperaldosteronism (PHA) based on the high effective liquid chromatography (HELC).Design and methods.We evaluated 98 patients with PHA and with essential hypertension (EHTN). Aldosterone and plasma renin activity were measured by radioimmunoassay, renin levels by immunoassay. The blood levels of cortisol (F), cortisone (E), corticosterone (B), 11‑deoxycorticosterone (DOC), 11‑dehydrocortitocosterone (A), 11‑deoxycortisol (S), 18‑hydroxycorticosterone (18‑OH-B), the urinary excretion of free cortisol (UFF), free cortisone (UFE), 18‑hydroxycorticosterone (U18‑OH-B) were measured by HELC. Dexamethasone test, saline infusion test, postural test, computed tomography of adrenal glands were performed. All PHA patients underwent adrenal vein sampling (AVS).Results.PHA patients had higher blood levels of B, DOC, 18‑OH-B and urinary excretion of U18‑OH-B than EHTN patients. Moreover, patients with aldosteroma had combined excess of blood B, DOC, 18‑OH-B and urinary excretion of U18‑OH-B, patients with idiopathic hyperaldosteronism (IHA) showed a reduction of F/E and B/А blood ratios and UFF/UFE urine ratio. The blood levels of B, DOC, 18‑OH-B and urinary excretion of U18‑OH-B showed the highest sensitivity and specificity for the diagnosis of PHA. Patients with aldosteroma showed higher levels of B and 18‑OH-B, higher ratios B/А, B/F and 18‑OHB/F in the adrenal vein blood at the tumor side as compared with those in patients with IHA.Conclusions.B, DOC, 18‑OH-B blood levels and U18‑OH-B urinary excretion determined by HELC are informative and reliable indicators for early diagnosis of PHA. The use of HELC method in a complex examination of PHA patients is necessary in case of aldosterone-renin ratio between 30 and 50 ng/dl per ng/(ml per hour) and in case of borderline values of lateralization coefficient at AVS.

MicroRNA-24 Is a Novel Regulator of Aldosterone and Cortisol Production in the Human Adrenal Cortex

Dysregulation of aldosterone or cortisol production can predispose to hypertension, as seen in aldosterone-producing adenoma, a form of primary aldosteronism. We investigated the role of microRNA (miRNA) in their production, with particular emphasis on the CYP11B1 (11β-hydroxylase) and CYP11B2 (aldosterone synthase) genes, which produce the enzymes responsible for the final stages of cortisol and aldosterone biosynthesis, respectively. Knockdown of Dicer1, a key enzyme in miRNA maturation, significantly altered CYP11B1 and CYP11B2 expression in a human adrenocortical cell line. Screening of nondiseased human adrenal and aldosterone-producing adenoma samples yielded reproducible but distinctive miRNA expression signatures for each tissue type, with levels of certain miRNA, including microRNA-24 (miR-24), differing significantly between the 2. Bioinformatic analysis identified putative binding sites for several miRNA, including miR-24, in the 3' untranslated region of CYP11B1 and CYP11B2 mRNAs. In vitro manipulation of miR-24 confirmed its ability to modulate CYP11B1 and CYP11B2 expression, as well as cortisol and aldosterone production. This study demonstrates that Dicer-dependent miRNA, including miR-24, can post-transcriptionally regulate expression of the CYP11B1 and CYP11B2 genes. Normal adrenal tissue and aldosterone-producing adenoma differ significantly and reproducibly in their miRNA expression profiles, with miR-24 significantly downregulated in the latter. Adrenal miRNA may, therefore, be a novel and valid target for the therapeutic manipulation of corticosteroid biosynthesis.

Diagnosis of Glucocorticoid-Remediable Aldosteronism in Hypertensive Children

Objective: Glucocorticoid-remediable aldosteronism (GRA) is caused by the presence of a chimeric gene originating from an unequal cross-over between the CYP11B1 and CYP11B2 genes. Aldosterone suppression by dexamethasone and high 18-hydroxycortisol (18-OHF) levels have been used to differentiate GRA from the other forms of primary aldosteronism. Methods: A dexamethasone suppression test including serum 18-OHF determination and the measurement of urinary excretion of aldosterone, its metabolites and 18-OHF were performed in 3 children of a family with primary aldosteronism. Polymerase chain reactions were performed to identify the chimeric gene. Results: The chimeric gene was identified in 2 children, their mother and grandmother. The affected children had an aldosterone-to-plasma renin activity ratio >30, elevated serum 18-OHF concentration and increased urinary excretion of aldosterone, its metabolites, and 18-OHF. Post-dexamethasone concentrations of serum aldosterone and 18-OHF concentrations were suppressed. Conclusion: Although very rare, the possible diagnosis of GRA should be considered in all children or young adults with low-renin hypertension. Since genetic testing is more specific than biochemical testing, a definitive diagnosis can only be obtained by identification of the CYP11B1/CYP11B2 chimeric gene.

Differential diagnostics of primary hyperaldosteronism: The role and significance of comparative selective blood sampling from adrenal veins

Primary hyperaldosteronism is known to be one of the commonnest causes of arterial hypertension. The authors propose a diagnostic protocol for primary hyperaldosteronism and a method for comparative selective blood sampling from adrenal veins. This method is described as the sole tool for differential diagnostics of different nosological forms of primary hyperaldosteronism. A clinical case of idiopathic hyperaldosteronism is presented.

Can the dextroenantiomer of the aromatase inhibitor fadrozole be useful for clinical investigation of aldosterone-synthase inhibition?

The beneficial effects of spironolactone, eplerenone, amiloride and potassium in preventing cardiovascular damage in various experimental models of salt-induced hypertension can be dissociated from blood pressure effects, and have drawn attention to the direct genomic and non-genomic actions of aldosterone at the level of the vessels, the heart and the kidneys. Exposure to endogenous aldosterone could be decreased by direct and specific aldosterone-synthase inhibition. FAD 286A, the dextroenantiomer of the aromatase inhibitor fadrozole, might be a first candidate to investigate in humans, the physiological impact and therapeutic properties of aldosterone-synthase inhibition, especially in various forms of primary aldosteronism.

Primary aldosteronism: evolving concepts in diagnosis and treatment

Purpose of review There has been a renaissance in the interest of aldosterone in the last few years. Hypersecretion of aldosterone, whether primary or secondary, is a frequent cause of hypertension and cardiovascular damage and primary aldosteronism (PA) is now recognized as the most frequent secondary form of hypertension. Recent findings Prospective studies of its prevalence around the world have demonstrated that primary aldosteronism occurs in 6-10% of patients with essential hypertension. Patients with potentially curable aldosterone producing adenomas are being recognized earlier than before. Diagnostic screening done by measurement of the plasma aldosterone/renin ratio followed by confirmatory tests has been responsible for the marked increase in the number of cases diagnosed. Most patients diagnosed in the last two decades did not have hypokalemia, however recent studies suggest that the usual way of obtaining blood for the measurement of potassium produces a spurious elevation of potassium and the impression of normokalemia. Recent studies have recognized that some forms of primary aldosteronism have a genetic basis, although the exact abnormality remains unclear. A revival of the use of adrenal vein catheterization has allowed the identification of many cases of unilateral adrenal pathology producing hyperaldosteronism that present with negative imagining studies. In the last year a new spironolactone derivative, eplerenone, has been marketed that does not have the anti-androgenic effects that spironolactone had and represents a significant advance in therapy for primary aldosteronism. Summary In summary, in the last few years primary aldosteronism has increasingly been recognized as an important cause of hypertension. With more refined diagnostic techniques, more surgically correctable forms are being identified and cured. The development of more specific mineralocorticoid

Medical management of primary hyperaldosteronism.

Most forms of primary aldosteronism are surgically correctable. However, when surgery is not appropriate, medical management is just as effective in correcting the pathophysiologic abnormalities due to aldosterone excess. A prerequisite for the rational medical management of primary aldosteronism is an understanding of the mechanisms that sustain hypertension. Primary aldosteronism can be associated with severe and resistant hypertension, and persistent hypervolemia is the primary reason for resistance to therapy. Patients with overriding comorbidities or strong preferences have been medically treated over the intermediate term of 5 to 7 years without evidence of escape or evidence of malignant transformation of adrenal adenomas.

Primary aldosteronism: rare bird or common cause of secondary hypertension?

Wider application of the aldosterone/plasma renin activity ratio among hypertensives has facilitated the detection of primary aldosteronism at earlier stages of evolution (with most patients normokalemic), and found prevalence rates far greater than those previously reported. Reliable detection of patients with PAL requires that 1) the diagnosis is considered in all hypertensives; 2) blood samples are collected under standardized conditions of diet, posture, and time of day; 3) medications known to alter the ratio are avoided or their effects taken into account; 4) aldosterone and plasma renin activity are measured using consistently accurate assay techniques; and 5) reliable methods (such as fludrocortisone suppression testing) are used to confirm primary aldosteronism. Adrenal venous sampling is the only dependable way to differentiate aldosterone-producing adenoma from bilateral adrenal hyperplasia. As has occurred in familial hyperaldosteronism type I, the elucidation of genetic mutations causing other forms of primary aldosteronism should further facilitate detection of this potentially curable or specifically treatable variety of hypertension.

Recombinant CYP11B genes encode enzymes that can catalyze conversion of 11-deoxycortisol to cortisol, 18-hydroxycortisol, and 18-oxocortisol.

CYP11B1 (11beta-hydroxylase) and CYP11B2 (aldosterone synthase) are 93% identical mitochondrial enzymes that both catalyze 11beta-hydroxylation of steroid hormones. CYP11B2 has the additional 18-hydroxylase and 18-oxidase activities required for conversion of 11-deoxycorticosterone to aldosterone. These two additional C18 conversions can be catalyzed by CYP11B1 if serine-288 and valine-320 are replaced by the corresponding CYP11B2 residues, glycine and alanine. Here we show that such a hybrid enzyme also catalyzes conversion of 11-deoxycortisol to cortisol, 18-hydroxycortisol, and 18-oxocortisol. These latter two steroids are present at elevated levels in individuals with glucocorticoid suppressible hyperaldosteronism (GSH) and some forms of primary aldosteronism. Their production by the recombinant CYP11B enzyme is enhanced by substitution of further amino acids encoded in exons 4, 5, and 6 of CYP11B2. A converted CYP11B1 gene, containing these exons from CYP11B2, would be regulated like CYP11B1, yet encode an enzyme with the activities of CYP11B2, thus causing GSH or essential hypertension. In a sample of 103 low renin hypertensive patients, 218 patients with primary aldosteronism, and 90 normotensive individuals, we found a high level of conversion of CYP11B genes and four cases of GSH caused by unequal crossing over but no gene conversions of the type expected to cause GSH.

Diagnosis of Glucocorticoid-Remediable Aldosteronism in Primary Aldosteronism: Aldosterone Response to Dexamethasone and Long Polymerase Chain Reaction for Chimeric Gene

Aldosterone suppression by dexamethasone, and high 18-hydroxycortisol and 18-oxocortisol levels are used to differentiate glucocorticoid-remediable aldosteronism (GRA) from other forms of primary aldosteronism. These methods are time consuming, expensive, and impractical for large studies. Moreover, diagnosis of GRA requires a confirmatory genetic test. We evaluated 117 patients with primary aldosteronism referred to our centers by the use of a long PCR technique to reveal the chimeric gene of GRA. In 60 of 117 patients, the response of aldosterone to dexamethasone (2 mg/day for 4 days) was also assessed. None of our patients, including 2 pairs of siblings, was positive for the chimeric gene. The results of long PCR were confirmed by Southern blotting. Despite a negative genetic test, 6 patients (1 with aldosterone-producing adenoma and 5 with idiopathic hyperaldosteronism) had plasma aldosterone suppressed by dexamethasone (i.e. ≤2 ng/dL). Of 117 patients, 43 were identified as having aldosterone-producing adenoma and 74 as having idiopathic hyperaldosteronism. In our experience, the long PCR technique is a reliable and simple test to at least exclude GRA in patients with primary aldosteronism. A short term dexamethasone suppression test of aldosterone can be misleading in identifying GRA. The prevalence of GRA in primary aldosteronism remains to be established.

Impaired Potassium-Stimulated Aldosterone Production: A Possible Explanation for Normokalemic Glucocorticoid-Remediable Aldosteronism1

Unlike other forms of primary aldosteronism, recent prospective studies have paradoxically revealed that glucocorticoid-remediable aldosteronism (GRA) is usually characterized by normal potassium (K+) levels. To evaluate this paradox we studied 10 GRA subjects and 14 healthy controls in two protocols: 1) the renal K+ excretory response to acute oral administration of 50 mmol K+ chloride and to fludrocortisone, 0.2 mg p.o. q12 h x 4 doses; and 2) the aldosterone response to administration of 50 mmol K+ chloride. The K+ excretion rate (KER) in GRA subjects (n = 6) at baseline (45.6 +/- 8.3 microEq/min), after K+ (134 +/- 34.2 microEq/min), and after fludrocortisone (100 +/- 35.0 microEq/min) was not significantly different than that seen in the control (n = 8) subjects (54.9 +/- 19.0, 154 +/- 35.5, 112 +/- 45.8 microEq/min, respectively). Thus the renal kaliuretic response to K+ ingestion and exogenous mineralocorticoid is normal in GRA. Serum aldosterone increased from 5.0 +/- 3.8 at baseline to a maximum of 13.1 +/- 6.6 ng/dL 60 min after K+ ingestion in control subjects (n = 7), but failed to increase in GRA subjects (n = 14), going from 8.7 +/- 3.8 (baseline) to 8.8 +/- 5.4 ng/dL at 60 min (P = 0.004 vs. control). The blunted aldosterone response to K+ in GRA in association with the sharp diurnal decline in aldosterone in this ACTH-regulated syndrome probably results in a milder degree of hyperaldosteronism compared with other forms of primary aldosteronism, thereby producing volume expansion with minimal renal K+ wasting.

Diagnosis and Treatment of Primary Aldosteronism

Disorders of the adrenal cortex and medulla are often associated with hypertension, which can be cured surgically in many cases or may require specific and timely medical treatments. Therefore, knowledge of adrenal physiology, biochemistry, and molecular biology is essential such that an appropriate diagnostic evaluation can be conducted efficiently. The most common hypertensive disorder of the adrenal cortex is primary aldosteronism. Aldosterone-producing adenoma is the most common form of primary aldosteronism and is most likely to be cured by unilateral adrenalectomy when aldosterone production is highly autonomous from renin-angiotensin, lateralizes to one adrenal gland, and is associated with overproduction of 18-hydroxycortiocosterone and C18-methyloxygenated metabolites of cortisol. Variants of adrenal hyperplasia that share these characteristics can also be cured by unilateral adrenalectomy.

A New Diagnostic Test for Primary Aldosteronism

Isotonic-isooncotic central volume expansion by head-out water immersion was induced in six aldosterone-producing adenoma subjects and in six patients with idiopathic hyperaldosteronism. Plasma renin activity and plasma aldosterone levels did not significantly change during water immersion while serum cortisol was significantly suppressed (P less than .001) and the aldosterone-cortisol ratio increased (P less than .02) in aldosterone-producing adenoma patients. Water immersion also revealed the failure of plasma aldosterone levels to decrease below 10 ng/dL in these subjects, thus confirming previous results obtained during isotonic saline infusion. Otherwise, plasma renin activity and plasma aldosterone were significantly reduced (P less than .05 and P less than .01 respectively) by water immersion and plasma aldosterone invariably fell below 10 ng/dL in patients with idiopathic aldosteronism. In view of the diagnostic reliability of such a suppression test we conclude that water immersion is suitable for discriminating between the two forms of primary aldosteronism. We therefore suggest its use for assessing renin-aldosterone responsiveness in primary aldosteronism.

Dexamethasone-suppressible hyperaldosteronism: Pathophysiology, clinical aspects, and new insights into the pathogenesis

A profile of dexamethasone-suppressible hyperaldosteronism (DSH), a variant of primary aldosteronism, is drawn by reviewing its pathophysiological and clinical aspects. Genetic studies show no HLA linkage and point to an autosomal dominant mode of inheritance, suggesting that the prevalence of this disease has been underestimated in the past. Hypertension, hypokalemia, suppressed renin, and high aldosterone values characterize DSH in the basal state, similar to the other forms of primary aldosteronism, i.e., aldosterone-producing adenoma (APA) or bilateral idiopathic adrenal hyperplasia (IAH). Biochemically DSH and APA can be differentiated from IAH since in both aldosterone does not respond to upright posture, to angiotensin II infusion, and to angiotensin-converting enzyme (ACE) captopril. In contrast, morphologically DSH is similar to IAH, since neither macroscopic nor histologic examinations of the adrenals give evidence of any unilateral abnormality. However, DSH is differentiated from APA and IAH by the hyperresponsiveness of aldosterone to acute ACTH administration as well as by the failure of aldosterone to escape from prolonged ACTH stimulation. The final diagnosis of DSH rests upon the prompt reversal of the features of mineralocorticoid excess by glucocorticoid therapy. In some cases hypertension is unresponsive to dexamethasone and needs alternative treatment. The main pathogenetic hypotheses point to a pituitary and/or an adrenal abnormality, but the intrinsic nature of the disease remains to be elucidated.

Use of the Saline Infusion Test to Diagnose the Cause of Primary Aldosteronism

Angiiensin II has a major effect on minerakcorticoid hormone synthesis in patients with idiiathii hyperakksteronism; lt has liile or no effect in those with an aldosterone-producing adenoma. To determine if thii difference could be of use in clinically separating these two forms of primary aldosteronism, saline infusion tests were performed in 20 patients-14 with surgically proved aldosterone-producing adenoma and six with ldiopathk hyperafdosteronism. With the patients receiving a balanced diet containing 120 meq of sodium, 1,250 ml of lsotonlc saline was infused intravenously between 8 A.M. and 10 A.M. after overnight recumbency. Plasma samples were obtained immediately before and after the infusion. Plasma cortiil level decreased approprlately in both groups, but plasma renin concentration decreased only in those patients with idiopathic hyperaldosterontsm (p <0.05). Aldoeterone and 18-hydroxycortkosterone levels decreased in both groups. To account for the circadian variation in adrenocorlkotropin levels during the course of saline infusion, 1&hydroxycortiiosterone/cortlsol and aldosterone/cortiil ratios were examined. Both ratios Increased in every patient with aldosterone-producing adenoma (p <O.Ol and p <O.OOl, respectively), but these ratios remained unchanged or decreased in the patients with idiopathic hyperaldosteronlsm. This divergent variation in ratios after saline infusion allows for the dlfferentlatkn of patients wlth an aldosterone-producing adenoma from those with idiopathic hyperaldosteronism. In patients with primary aldosteronlsm, an 18-hydroxycorticosterone/cortisol ratlo of less than 3.0 or an aldosterone/cortlsol ratio of less than 2.2 afler saline lnfuslon is diagnostic of idiopathic hyperaldosteronism.