Primary aldosteronism: emerging trends

Utility of right adrenal signature veins in venous sampling for primary aldosteronism

BACKGROUND

This study aimed to identify the appropriate signature veins for the right adrenal gland using a 3D model fused with adrenal venography images and to verify their accuracy through the selectivity index (SI) >2.

METHODS

We analyzed the right adrenal venography images of 41 patients who underwent adrenal venous sampling (AVS). These images were merged with a 3D structure of the adrenal gland to identify the signature veins of the right adrenal gland. We then used the signature veins observed during adrenal venography to determine the optimal position of the catheter tip during AVS for 53 other patients. Finally, we verified the accuracy of this method according to the SI.

RESULTS

We successfully fused the 3D models of 41 cases with adrenal venography images. We identified the trunk branch type as the major venous morphology in the right anterior oblique at degrees of 30 (38 cases, 92.7%). In addition, the central vein, brush vein, uvula vein, and capsular vein were identified as signature veins for the right AVS. The accuracy of AVS was 100% in the other 53 patients, as verified by an SI >2.

CONCLUSIONS

Our study identified the right adrenal signature veins, including the previously overlooked uvula vein, which can be used to determine the position of the catheter tip and improve the success rate of AVS.

Management of adreno-cortical adenomas using microwave ablation: study of the effects of the fat tissue

BACKGROUND AND OBJECTIVES

Adrenocortical neoplasms are the main causes of secondary hypertension and related comorbidities including hypokalemia and cardiovascular diseases. Conventional techniques for the management of this condition are often invasive and not resolutive. Recent studies proposed microwave thermal ablation (MWA) to eradicate adrenocortical adenomas arising in proximity to sensitive structures. This study explores a new MWA approach to selectively direct the electromagnetic energy into the target and shield the surrounding tissues. The new solution relies on the anatomical and dielectric characteristics of the adrenal gland and the surrounding fat capsule.

METHODS

A 3 D model of the adrenal gland is developed, and a cooled microwave applicator is placed parallel to the interface between the fat and adrenal tissue. Numerical simulations are conducted at 2.45 GHz accounting for two energy delivery settings, two orientations of the applicator and blood perfusion of the tissues. Ex vivo and in vivo ablation procedures are conducted on ovine adrenal glands. Histology analysis completes the experimental studies.

RESULTS

Numerical results show asymmetric ablation profiles in ex vivo and in vivo conditions. The asymmetry ratio is influenced by the procedure settings and orientation of the applicator. Ablation zones obtained experimentally agree with those predicted by the numerical simulations. Histology analysis confirms irreversible cellular changes only in the adrenal tissue close to the applicator.

CONCLUSIONS

The outcomes show that the dielectric contrast between the fat layer and tissue target can be a tool in MWA to shape ablation zones to protect the surrounding structures from excessive temperature increases.

The Importance of Correlation between Aldosterone and Parathyroid Hormone in Patients with Primary Hyperparathyroidism

In primary hyperparathyroidism, an increased risk of developing the cardiovascular disease may exist due to increased activity of the renin-angiotensin-aldosterone system. The aim of this study was to evaluate the relationship between parathyroid hormone and aldosterone in patients with primary hyperparathyroidism. The study included 48 patients with primary hyperparathyroidism and 30 healthy subjects who matched age and gender to the study group. This study was conducted at the Center for Laboratory medicine, Clinical center of Vojvodina, Novi Sad, Serbia. In addition to clinical data and laboratory determination of the concentration of total and ionized calcium, phosphorus, measurements of parathyroid hormone, vitamin D, direct renin, and aldosterone were performed by the method of chemiluminescent technology. Compared to the controls, the study group had statistically significantly higher values of aldosterone (p=0.028), total calcium (p=0.01), ionized calcium (p=0.003) and parathyroid hormone (P ≤ 0.001) Serum aldosterone and parathyroid hormone levels were correlated positively in patients with primary hyperparathyroidism (r=0.509, p < 0.05). A statistically significant positive correlation between renin and parathyroid hormone (r=0.688, p < 0.05) and renin and calcium (r=0.673, p < 0.05) was determined in hyperparathyroid patients. In multivariate regression analysis, the strongest predictive variable of aldosterone secretion was parathyroid hormone (p=0.011). An independent relationship between parathyroid hormone and aldosterone in patients with primary hyperparathyroidism and the correlation between renin and parathyroid hormone as well as with calcium indicate not only the direct but also the indirect associations between parathyroid hormone and aldosterone in primary hyperparathyroidism. These findings may represent another possible model of renin-angiotensin-aldosterone-induced organ damage.

Age- and sex-specific reference ranges are needed for the aldosterone/renin ratio

OBJECTIVE

Current Endocrine Society Clinical Practice Guidelines use a specific aldosterone/renin ratio (ARR) threshold to screen for primary aldosteronism (a treatable disease causing up to 15% of hypertension in primary care) in all patients. We sought to characterize demographic variations in the ARR, hypothesizing a need for age- and sex-specific reference ranges to improve the accuracy of the test.

DESIGN

Retrospective cross-sectional analysis of ARR measurements at a single tertiary hospital from December 2016 to June 2018.

PATIENTS

A total of 442 patients with clinically indicated ARR were included, after excluding those who were on spironolactone or the oral contraceptive pill, were pregnant or had an existing adrenal condition.

MEASUREMENTS

Aldosterone, renin and the ARR.

RESULTS

Among those aged 20-39 years (n = 74), females had significantly higher median aldosterone (369 vs 244 pmol/L, P = .028), lower median renin (17.0 vs 27.6 mIU/L, P = .034) and higher median ARR (20.7 vs 10.3 (pmol/L)/(mIU/L), P = .001) than males, despite having lower systolic (135 vs 145 mmHg, P = .021) and diastolic (89 vs 96.5 mmHg, P = .007) blood pressure. The ≥ 60-year age group (n = 157) also had significant sex differences in the ARR. With increasing age (20-39 vs ≥ 60 years), there was a significant fall in plasma aldosterone in females (369 pmol/L vs 264 pmol/L, P = .005), with no change observed in males.

CONCLUSIONS

For those 20-39 years old, aldosterone and the ARR are significantly higher in females despite a lower systolic and diastolic BP, highlighting the potential for false-positive results. Our findings indicate the need for prospective studies with a control population to define age- and sex-specific ARR reference ranges.

Effects of Mineralocorticoid and AT1 Receptor Antagonism on The Aldosterone-Renin Ratio In Primary Aldosteronism-the EMIRA Study

CONTEXT

While current guidelines recommend the withdrawal of mineralocorticoid receptor antagonist (MRA) and renin-angiotensin system blockers for the screening and detection of primary aldosteronism (PA), this can worsen hypokalemia and control of high blood pressure (BP) values.

OBJECTIVE

To investigate whether aldosterone/renin ratio (ARR) values were affected by the MRA canrenone and/or by canrenone plus olmesartan treatment in patients with PA.

DESIGN

Within-patient study.

SETTING

The European Society of Hypertension center of excellence at the University of Padua.

PATIENTS

Consecutive patients with an unambiguous diagnosis of PA subtyped by adrenal vein sampling.

INTERVENTIONS

Patients were treated for 1 month with canrenone (50-100 mg orally), and for an additional month with canrenone plus olmesartan (10-20 mg orally). Canrenone and olmesartan were up-titrated over the first 2 weeks until BP values and hypokalemia were controlled. Patients with unilateral PA were adrenalectomized; those with bilateral PA were treated medically.

MAIN OUTCOME MEASURES

BP, plasma levels of sodium and potassium, renin and aldosterone.

RESULTS

Canrenone neither lowered plasma aldosterone nor increased renin; thus, the high ARR and true positive rate remained unaffected. Addition of the angiotensin type 1 receptor blocker raised renin and slightly lowered aldosterone, which reduced the ARR and increased the false negative rate.

CONCLUSIONS

At doses that effectively controlled serum potassium and BP values, canrenone did not preclude an accurate diagnosis in patients with PA. Addition of the angiotensin type 1 receptor blocker olmesartan slightly raised the false negative rate. Hence, MRA did not seem to endanger the accuracy of the diagnosis of PA.

Effects of Primary Aldosteronism and Different Therapeutic Modalities on Glucose Metabolism

Despite findings that aldosterone impairs glucose metabolism, studies concerning the effect of primary aldosteronism (PA) and its treatment on glucose metabolism are controversial. We aimed to determine glucose metabolism in PA and the effect of the treatment modality. We compared glucose metabolism between PA patients (N = 286) and age-, sex-, and body mass index-matched controls (N = 816), and the changes in glucose metabolism depending on the treatment modality (adrenalectomy vs. spironolactone treatment). Hyperglycemia including diabetes mellitus (DM; 19.6% vs. 13.1%, p = 0.011) was more frequent in PA patients. Hyperglycemia was also more frequent in PA patients without subclinical hypercortisolism (SH: p < 0.001) and in those regardless of hypokalemia (p < 0.001-0.001). PA patients and PA patients without SH had higher DM risk (odds ratio (OR); 95% confidence interval (CI): 1.63; 1.11-2.39 and 1.65; 1.08-2.51, respectively) after adjusting confounders. In PA patients, there was significant decrease in the DM prevalence (21.3% to 16.7%, p = 0.004) and fasting plasma glucose (p = 0.006) after adrenalectomy. However, there was no significant change in them after spironolactone treatment. Adrenalectomy was associated with more improved glucose status than spironolactone treatment (OR; 95% CI: 2.07; 1.10-3.90). Glucose metabolism was impaired in PA, regardless of hypokalemia and SH status, and was improved by adrenalectomy, but not spironolactone treatment.

Familial hyperaldosteronism type III a novel case and review of literature

Less than 15% of hypertension cases in children are secondary to a primary hyperaldosteronism. This is idiopathic in 60% of the cases, secondary to a unilateral adenoma in 30% and 10% remaining by primary adrenal hyperplasia, familial hyperaldosteronism, ectopic aldosterone production or adrenocortical carcinoma.To date, four types of familial hyperaldosteronism (FH I to FH IV) have been reported. FH III is caused by germline mutations in KCNJ5, encoding the potassium channel Kir3.4. The mutations cause the channel to lose its selectivity for potassium, allowing large quantities of sodium to enter the cell. As a consequence, the membrane depolarizes, voltage-gated calcium channels open, calcium enters the cell, initiating the cascade that leads to aldosterone synthesis. Somatic mutations in KCNJ5 has also been described in aldosterone-producing adenomas. The most frequent presentation of FH III is with severe hyperaldosteronism symptoms and resistance to pharmacological therapy which leads to bilateral adrenalectomy. We will review current literature and describe a child with FH III due to a novel de novo deletion in KCNJ5 with wild phenotype as a sign of clinical variability of this disease.

[Long-term blood pressure outcome after unilateral adrenalectomy for primary hyperaldosteronism]

OBJECTIVES

To evaluate long-term results of adrenalectomy for primary aldosteronism (PA) and to identify prognostic factors associated.

METHODS

Exhaustive retrospective review of all consecutive patients undergoing adrenalectomy for PA between 2002 and 2013 in our department. All patients underwent preoperative: clinical evaluation (age, sex, height, weight, systolic and diastolic BP under treatment, identification of anti-hypertension treatment), biological evaluation (potassium, renin, aldosterone) and radiological evaluation (CT and/or MRI). Blood pressure was assessed postoperatively at 1 month, 1 year, then at the date of the latest news. The patients were classified into three categories: cured (no antihypertensive therapy in postoperative associated with strictly lower blood pressures of 140/90mmHg), improved (decreased number of drugs or number unchanged but with better blood pressure control), and refractory (no change in the number of drug and blood pressure, or deterioration of one or other of these two parameters).

RESULTS

We evaluated 43 patients, 23 men and 20 women, with a median follow-up of 74.4 months [16.8 to 141]. Pathological analysis described 34 adenomas (79%), 7 hyperplasias (16%) (5 micro-nodular and 2 macro-nodular) and 2 adrenocortical carcinoma (5%). The postoperative long-term assessment found 20% of cured patients (n=8), 65% of improved (n=26) and 15% of refractory (n=6). Prognostic factors associated with favorable long-term blood pressure outcome were those typically associated with ARS score [preoperative number of anti-hypertension drugs (P=0.005), BMI<25kg/m² (P=0.009), and duration of hypertension (P=0.007)].

CONCLUSION

Adrenalectomy for PA is a long-term effective treatment for blood pressure control. Prognostic factors associated with long-term success are those conventionally described in ARS score.

LEVEL OF EVIDENCE

4.

Regulation of zonation and homeostasis in the adrenal cortex

The adult adrenal cortex is organized into concentric zones, each specialized to produce distinct steroid hormones. Cellular composition of the cortex is highly dynamic and subject to diverse signaling controls. Cortical homeostasis and regeneration rely on centripetal migration of steroidogenic cells from the outer to the inner cortex, which is accompanied by direct conversion of zona glomerulosa (zG) into zona fasciculata (zF) cells. Given the important impact of tissue structure and growth on steroidogenic function, it is essential to understand the mechanisms governing adrenal zonation and homeostasis. Towards this end, we review the distinctions between each zone by highlighting their morphological and ultra-structural features, discuss key signaling pathways influencing zonal identity, and evaluate current evidence for long-term self-renewing stem cells in the adult cortex. Finally, we review data supporting zG-to-zF transdifferentiation/direct conversion as a major mechanism of adult cortical renewal.

[Not Available]

Zusammenfassung. In diesem Mini-Review wird aufgezeigt, dass die Diagnostik der sekundären Hypertonie eigentlich eine relativ einfache Unternehmung ist. Neben einer umfassenden Anamnese sowie einer korrekt durchgeführten klinischen Untersuchung muss bei jeder Diagnosestellung einer arteriellen Hypertonie an die Möglichkeit einer sekundären Ursache gedacht werden. Oft ist es auch kostengünstiger, beim geringsten Verdacht direkt nach einer sekundären Ursache zu suchen, als durch langwierige Umstellungen der Therapie und damit auch Verunsicherung des Patienten die Diagnostik zu verzögern.

Downregulation of miR-375 in aldosterone-producing adenomas promotes tumour cell growth via MTDH

OBJECTIVE

Previous studies have investigated the genetic and molecular basis of primary aldosteronism (PA), a common cause of human hypertension, but the effects of microRNAs (miRNAs) on the adrenocortical cell proliferation and aldosterone production are largely obscure. Here, we characterized miRNA expression patterns in the subtypes of PA to gain a better understanding of its pathogenesis.

METHODS

miRNA expression was assessed by microarray profiling analysis in aldosterone-producing adenoma (APA), unilateral adrenal hyperplasia (UAH) and normal adrenal cortex tissues. Selected differentially expressed miRNAs were further validated in a validation cohort by qRT-PCR. A gain-of-function approach was used to explore the functional role of the specific miRNA in vitro.

RESULTS

Of 31 miRNAs including miR-375, miR-7 and miR-29b were found to be significantly differentially expressed among these three groups. miR-375 was the most downregulated one in adrenal cortex tissues from PA patients, and its expression level was inversely correlated with the tumour size in APA. Overexpression of miR-375 in a human adrenocortical cell line (H295R) reduced cell proliferation and suppressed the expression of MTDH (metadherin, also known as astrocyte elevated gene-1). Moreover, MTDH was verified as a direct target of miR-375 through luciferase reporter assays. Knock-down of MTDH in H295R cells attenuated Akt-Ser473 phosphorylation and inhibited cell viability.

CONCLUSION

Our findings suggest that miR-375 exerts its tumour-suppressive function via targeting MTDH/Akt pathway and implicate a potential therapeutic target in PA.

Management of adrenal tumors in pregnancy

Adrenal diseases, including Cushing syndrome (CS), primary aldosteronism (PA), pheochromocytoma, and adrenocortical carcinoma, are uncommon in pregnancy; a high degree of clinical suspicion must exist. Physiologic changes to the hypothalamus-pituitary-adrenal axis in a normal pregnancy result in increased cortisol, renin, and aldosterone levels, making the diagnosis of CS and PA in pregnancy challenging. However, catecholamines are not altered in pregnancy and allow a laboratory diagnosis of pheochromocytoma that is similar to that of the nonpregnant state. Although adrenal tumors in pregnancy result in significant maternal and fetal morbidity, and sometimes mortality, early diagnosis and appropriate treatment often improve outcomes.

Surgical management of adrenocortical tumours

The surgical treatment of adrenal tumours has evolved over the past century, as has our understanding of which hormones are secreted by the adrenal glands and what these hormones do. This article reviews the preoperative evaluation of patients with adrenal tumours that could be benign or malignant, including metastases. The biochemical evaluation of excess levels of hormones is discussed, as are imaging characteristics that differentiate benign tumours from malignant tumours. The options for surgical management are outlined, including the advantages and disadvantages of various open and laparoscopic approaches. The surgical management of adrenocortical carcinoma is specifically reviewed, including controversies in operative approaches as well as surgical management of invasive or recurrent disease.

Bone and mineral metabolism in patients with primary aldosteronism

Primary aldosteronism represents major cause of secondary hypertension, strongly associated with high cardiovascular morbidity and mortality. Aldosterone excess may influence mineral homeostasis, through higher urinary calcium excretion inducing secondary increase of parathyroid hormone. Recently, in a cohort of PA patients a significant increase of primary hyperparathyroidism was found, suggesting a bidirectional functional link between the adrenal and parathyroid glands. The aim of this study was to evaluate the impact of aldosterone excess on mineral metabolism and bone mass density. In 73 PA patients we evaluated anthropometric and biochemical parameters, renin-angiotensin-aldosterone system, calcium-phosphorus metabolism, and bone mineral density; control groups were 73 essential hypertension (EH) subjects and 40 healthy subjects. Compared to HS and EH, PA subjects had significantly lower serum calcium levels and higher urinary calcium excretion. Moreover, PA patients showed higher plasma PTH, lower serum 25(OH)-vitamin D levels, higher prevalence of vitamin D deficiency (65% versus 25% and 25%; P < 0.001), and higher prevalence of osteopenia/osteoporosis (38.5 and 10.5%) than EH (28% and 4%) and NS (25% and 5%), respectively. This study supports the hypothesis that bone loss and fracture risk in PA patients are potentially the result of aldosterone mediated hypercalciuria and the consecutive secondary hyperparathyroidism.