Impact of aldosterone-producing cell clusters on diagnostic discrepancies in primary aldosteronism

Impact of Conducting Adrenal Venous Sampling in the Morning Versus Afternoon in Primary Aldosteronism

Context

Adrenal venous sampling (AVS) is the gold standard technique for subtype differentiation of primary aldosteronism (PA) and to obtain aldosterone and cortisol measurements; however, their secretion patterns show fluctuations during the day.

Objective

We aimed to examine the effects of AVS timing on AVS results.

Methods

This multicenter, retrospective, observational study included a total of 753 patients who were diagnosed with PA and underwent AVS in 4 centers in Japan. Among them, 504 and 249 patients underwent AVS in the morning (AM-AVS) and in the afternoon (PM-AVS), respectively. The outcome measures were the impact of AVS timing and hormone fluctuations in a day on AVS results.

Results

There were no differences in the success rate of AVS, diagnostic rate of disease type, or frequency of discrepancy in PA subtypes between the AM-AVS and PM-AVS groups. Regarding patients with unilateral PA, aldosterone concentrations in adrenal venous blood did not differ between the 2 groups on the dominant or nondominant side. Conversely, regarding patients with bilateral PA, aldosterone concentrations in adrenal venous blood were significantly higher in the AM-AVS than in the PM-AVS group.

Conclusions

The timing of AVS did not seem to have a significant impact on subtype diagnosis. The aldosterone levels in adrenal venous blood were significantly higher in patients with bilateral PA in the AM-AVS group, but there was no such difference between patients with unilateral PA in the AM-AVS and PM-AVS groups. Each subtype may have a different hormone secretion pattern in a day.

Recurrence of Primary Aldosteronism After Surgery in Aldosterone-producing Adenoma With KCNJ5 Gene Mutation

Primary aldosteronism (PA) is a major cause of secondary hypertension. Aldosterone-producing adenoma (APA) is a subtype of PA, and adrenalectomy is the gold-standard treatment. Recently, a high prevalence of the KCNJ5 gene mutation has been reported in APA, particularly in Japan. Herein, we present 2 extremely rare cases of PA recurrence more than 10 years after adrenalectomy for APA. In the first case, a 52-year-old woman was examined for hypertension 22 years after total adrenalectomy of the right adrenal gland. Recurrent PA was diagnosed based on high aldosterone-renin-ratio (ARR), identification of left adrenal gland tumor by computed tomography (CT), and a confirmatory test. In the second case, a 65-year-old man was examined for hypertension 17 years after total adrenalectomy of the left adrenal gland. He had maintained his blood pressure using medication since the onset of hypertension 4 years after the surgery. A year later, a high ARR was observed. PA recurrence was determined by a right adrenal gland tumor noted on CT and a confirmatory test. Somatic mutations in KCNJ5 were detected in the resected tissues in both cases. We recommend careful follow-ups after adrenalectomy in APA cases, especially in those with a KCNJ5 gene mutation.

Effect of Intraprocedural Cortisol Measurement on ACTH-stimulated Adrenal Vein Sampling in Primary Aldosteronism

Context

Adrenocorticotropin (ACTH) loading is used to increase the success rate of adrenal vein sampling (AVS).

Objective

We aimed to determine the effect of intraprocedural cortisol measurement (ICM) on ACTH-stimulated AVS (AS-AVS) owing to a lack of reliable data on this topic.

Methods

This multicenter, retrospective, observational study took place in 28 tertiary centers in Japan. Among 4057 patients enrolled, 2396 received both basal AVS (B-AVS) and AS-AVS and were divided into 2 groups according to whether ICM was used. The effect of ICM on AS-AVS was measured.

Results

In patients who underwent both AVS procedures, the ICM group had significantly higher success rates for both B-AVS and AS-AVS than the non-ICM group did. However, the probability of failure of AS-AVS after a successful B-AVS and the probability of success of AS-AVS after a failed B-AVS were not significantly different in the 2 groups. For subtype diagnosis, propensity-score matching revealed no significant difference between the 2 groups, and the discrepancy rate between B-AVS and AS-AVS for subtype diagnosis was also not significantly different.

Conclusion

ICM significantly increased the success rate of B-AVS and AS-AVS in protocols in which both AVS procedures were performed and had no effect on subtype diagnosis. However, in protocols in which both AVS procedures were performed, the results suggest ICM may not be necessary when performing AS-AVS if ICM is used only when B-AVS is performed. Our study suggests that ICM during AVS plays an important role and should be recommended.

Case Report: Primary Aldosteronism Due to Bilateral Aldosterone-Producing Micronodules With HISTALDO Classical and Contralateral Non-Classical Pathology

BACKGROUND

Non-classical multiple aldosterone-producing micronodules/nodules (mAPM/mAPN) could be the pathogenesis of primary aldosteronism (PA). The co-existence of mAPM with adenomas harboring somatic mutations has not previously been reported.

METHODS

We presented a PA patient with bilateral mAPM and concomitant autonomous cortisol secretion (ACS).

RESULTS

A 46-year-old Taiwanese woman presented with hypertension, hypokalemia, and bilateral adrenal adenomas. A 1 mg low-dose dexamethasone suppression test showed elevated morning serum cortisol. An adrenal vein sampling (AVS) suggested a left-sided lateralization of hyperaldosteronism. A right partial adrenalectomy and a left total adrenalectomy were performed. The patient showed biochemical and hypertension remission after the operation. This patient had bilateral mAPM with concomitant ACS, a right histopathologically classical PA adenoma, and a left non-classical PA adenoma. The right adrenal adenoma showed CYP11B1-negative and CYP11B2-positive staining and harbored the KCNJ5-L168R mutation. The left adrenal adenoma showed CYP11B1-positive and CYP11B2-negative staining and harbored the PRKACA-L206R mutation.

CONCLUSION

In a PA patient with concomitant ACS, bilateral APM could coexist with both histopathologically classical and non-classical PA adenomas, each with different somatic mutations. The presence of ACS could lead to the misinterpretation of AVS results.

Subtypes of Histopathologically Classical Aldosterone-Producing Adenomas Yield Various Transcriptomic Signaling and Outcomes

[Figure: see text].

Para-chloro-2-[18F]fluoroethyl-etomidate: A promising new PET radiotracer for adrenocortical imaging

Introduction: [¹¹C]Metomidate ([¹¹C]MTO), the methyl ester analogue of etomidate, was developed as a positron emission tomography (PET) radiotracer for adrenocortical tumours and has also been suggested for imaging in primary aldosteronism (PA). A disadvantage of [¹¹C]MTO is the rather high non-specific binding in the liver, which impacts both visualization and quantification of the uptake in the right adrenal gland. Furthermore, the short 20-minute half-life of carbon-11 is a logistic challenge in the clinical setting. Objectives: The aim of this study was to further evaluate the previously published fluorine-18 (T_1/2=109.5 min) etomidate analogue, para-chloro-2-[¹⁸F]fluoroethyl etomidate; [¹⁸F]CETO, as an adrenal PET tracer. Methods: In vitro experiments included autoradiography on human and cynomolgus monkey (non-human primate, NHP) tissues and binding studies on adrenal tissue from NHPs. In vivo studies with [¹⁸F]CETO in mice, rats and NHP, using PET and CT/MRI, assessed biodistribution and binding specificity in comparison to [¹¹C]MTO. Results: The binding of [¹⁸F]CETO in the normal adrenal cortex, as well as in human adrenocortical adenomas and adrenocortical carcinomas, was shown to be specific, both in vitro (in humans) and in vivo (in rats and NHP) with an in vitro K_d of 0.66 nM. Non-specific uptake of [¹⁸F]CETO in NHP liver was found to be low compared to that of [¹¹C]MTO. Conclusions: High specificity of [¹⁸F]CETO to the adrenal cortex was demonstrated, with in vivo binding properties qualitatively surpassing those of [¹¹C]MTO. Non-specific binding to the liver was significantly lower than that of [¹¹C]MTO. [¹⁸F]CETO is a promising new PET tracer for imaging of adrenocortical disease and should be evaluated further in humans.

Functional Characteristic and Significance of Aldosterone-Producing Cell Clusters in Primary Aldosteronism and Age-Related Hypertension

Primary aldosteronism (PA) is one of the most frequent curable forms of secondary hypertension. It can be caused by the overproduction of aldosterone in one or both adrenal glands. The most common subtypes of PA are unilateral aldosterone over-production due to aldosterone-producing adenomas (APA) or bilateral aldosterone over-production due to bilateral hyperaldosteronism (BHA). Utilizing the immunohistochemical (IHC) detection of aldosterone synthase (CYP11B2) has allowed the identification of aldosterone-producing cell clusters (APCCs) with unique focal localization positive for CYP11B2 expression in the subcapsular portion of the human adult adrenal cortex. The presence of CYP11B2 supports that synthesis of aldosterone can occur in these cell clusters and therefore might contribute to hyperaldosteronism. However, the significance of the steroidogenic properties of APCCs especially in regards to PA remains unclear. Herein, we review the available evidence on the presence of APCCs in normal adrenals and adrenal tissues adjacent to APAs, their aldosterone-stimulating somatic gene mutations, and their accumulation during the ageing process; raising the possibility that APCCs may play a role in the development of PA and age-related hypertension.

Primary Aldosteronism with Parathyroid Hormone Elevation: A Single-center Retrospective Study

Objective Primary aldosteronism (PA) is a major cause of secondary hypertension. The association between PA and other hormone disorders is unclear. The present study aimed to evaluate whether the parathyroid hormone (PTH) value is associated with PA subtypes or specific treatments. Methods We enrolled 135 patients with PA who had their PTH value measured before undergoing a specific treatment. We evaluated whether PTH value is associated with PA subtypes or with specific treatments. The present study is a single-center retrospective study (2011-2018). Results Our study showed that, among the patients with PA, the proportion of those with PTH elevation was >30%. The PTH value was significantly correlated with both the basal plasma aldosterone concentration (PAC) and PAC after a captopril challenge test. However, the PTH value was not significantly different between the patients with unilateral and bilateral PA. We observed that the serum PTH value decreased after treatment of PA with unilateral adrenalectomy or mineralocorticoid receptor antagonists. Conclusion Our findings suggest that the PTH value in PA patients might be associated with the autonomous production of aldosterone. However, there was no correlation between the PTH value and PA subtypes in our study. Additionally, our study showed that targeted treatment for PA may lead to a decrease in the serum PTH levels. Hence, the PTH value could potentially be used as an index for measuring the suitability for PA treatment.

Primary Aldosteronism in the Elderly

CONTEXT

The clinical spectrum and knowledge of the molecular mechanisms underlying primary aldosteronism (PA), the most frequent form of endocrine hypertension, has evolved over recent years. In accordance with the Endocrine Society guidelines and in light of the growing evidence showing adverse cardiovascular outcomes, it is expected that a progressively wider population of patients affected by hypertension will be screened for PA, including the elderly.

EVIDENCE ACQUISITION

A systematic search of PubMed was undertaken for studies related to the renin-angiotensin-aldosterone system (RAAS), PA, and adrenal histopathology in the elderly population.

EVIDENCE SYNTHESIS

Several studies showed an age-dependent decrease in the activity of RAAS, together with a progressive decrease of the aldosterone response to sodium intake, particularly after the sixth decade of life. The positive correlation between age and serum aldosterone during liberal sodium intake over serum aldosterone during sodium restriction is paralleled by histological changes in adrenal aldosterone synthase (CYP11B2) expression patterns. Immunohistochemical studies showed a progressive loss of the continuous expression of CYP11B2 in the adrenal zona glomerulosa with aging and a concomitant increase of aldosterone-producing cell clusters, which might be responsible for relatively autonomous aldosterone production. Additionally, following PA confirmation and subtype diagnosis, older age is correlated with a lower benefit after adrenalectomy for unilateral PA.

CONCLUSIONS

Accumulating evidence suggests that RAAS physiology and regulation show age-related changes. Further studies may investigate to what extent these variations might affect the diagnostic workup of patients affected by PA.

Genetic and epigenetic analyses of aldosterone-producing adenoma with hypercortisolemia

DNA methylation is associated with excess cortisol and aldosterone. The DNA encoding aldosterone synthase (CYP11B2) and 11β-hydroxylase (CYP11B1), which catalyzes the final step of cortisol biosynthesis, is less methylated in aldosterone-producing adenomas (APA) and cortisol-producing adenomas (CPA), respectively. Several studies have reported specific gene mutations in APA and CPA, and some APAs also cause hypercortisolemia. The aim of this study was to clarify the molecular mechanisms of cortisol co-production in APA using genetic and epigenetic analyses. We evaluated 16 patients with APA between 2011 and 2018 at Kanazawa University Hospital (Ishikawa, Japan). The diagnostic criteria for hypercortisolemia were based on the guideline from the Endocrine Society. Gene mutation and DNA methylation analyses of the CYP11B2 and CYP11B1 promoters in APA were performed. Of the 16 patients with APA, six also had hypercortisolemia. In the genetic analysis, all six APAs with hypercortisolemia as well as eight of the 10 APAs without hypercortisolemia had a KCNJ5 mutation. In the epigenetic analyses, the methylation status of the CYP11B2 promoter was similar in the APAs with and without hypercortisolemia. However, in the APAs with hypercortisolemia, the CYP11B1 promoter was significantly less methylated, especially at two CpG sites near the Ad1/cAMP response element binding site within the CYP11B1 promoter. In conclusion, the genetic analysis revealed no association between hypercortisolemia and the evaluated gene mutations. However, the epigenetic analysis suggested that DNA methylation of the CYP11B1 promoter plays a role in concurrent hypercortisolemia and APA.

Primary aldosteronism subtype discordance between computed tomography and adrenal venous sampling

The primary aldosteronism (PA) subtype is usually confirmed by CT and adrenal venous sampling (AVS). However, the subtype diagnosis by AVS is not necessarily consistent with the subtype diagnosis by CT. Patients with PA who show bilateral lesions (normal-appearing adrenals or bilateral adrenal nodules) on CT but unilateral disease on AVS are often found. The aim of this study was to evaluate whether patients with PA subtype discordance between CT and AVS obtain benefits from unilateral adrenalectomy. We retrospectively analyzed 362 consecutive patients with PA who underwent both CT and adrenocorticotropic hormone-unstimulated AVS at Kanazawa University Hospital. Surgical outcomes for unilateral PA were evaluated according to the criteria of the Primary Aldosteronism Surgical Outcome study. In our study, the success rate of AVS in patients with bilateral lesions on CT was 89% (191/214). Furthermore, the discordance rate between CT and AVS in patients with bilateral lesions on CT was 39% (74/191). After surgery, patients with bilateral lesions on CT but unilateral disease on AVS (n = 17) had a lower complete biochemical success rate than those with unilateral lesions on CT and ipsilateral disease on AVS (n = 30) (41% vs. 80%, p = 0.01), but clinical and biochemical benefits (the complete and partial success combined) were not significantly different between them (76% vs. 93% (p = 0.11) and 70% vs. 90% (p = 0.10), respectively). In conclusion, patients with bilateral lesions on CT but unilateral disease on AVS benefited from surgery, and AVS should be performed for patients who pursue surgical management when the CT findings suggest bilateral lesions.

The Prevalence of Primary Aldosteronism and Evolving Approaches for Treatment

Over six decades since primary aldosteronism was first described, much has been learned about its prevalence and optimal treatment. Estimates of the prevalence of primary aldosteronism have increased considerably over the years, even exceeding 20% in some populations of resistant hypertension. Even in patients with normal blood pressures, the prevalence of overt primary aldosteronism and dysregulated aldosterone production may be more common than appreciated. Emerging data support the concept that primary aldosteronism may be better characterized as a continuum of renin-independent aldosterone production, whose severity influences the clinical presentation and risk for incident cardiovascular disease. Mineralocorticoid receptor antagonists and adrenalectomy are the mainstay treatments for primary aldosteronism and have long been considered equally efficacious. However, recent data suggest that while surgical adrenalectomy can effectively reduce cardiovascular risk, mineralocorticoid receptor antagonist therapy may require a physiologic approach to optimize efficacy.

Aldosterone and 18-Oxocortisol Coaccumulation in Aldosterone-Producing Lesions

Primary aldosteronism is a secondary hypertensive disease caused by autonomous aldosterone production that often caused by an aldosterone-producing adenoma (APA). Immunohistochemistry of aldosterone synthase (CYP11B2) shows the presence of aldosterone-producing cell clusters (APCCs) even in non-primary aldosteronism adult adrenal cortex. An APCC-like structure also exists as possible APCC-to-APA transitional lesions (a speculative designation) in primary aldosteronism adrenals. However, whether APCCs produce aldosterone or 18-oxocortisol, a potential serum marker of APA, remains unknown because of lack of technology to visualize adrenocorticosteroids on tissue sections. To address this obstacle, in this study, we used highly sensitive Fourier transform ion cyclotron resonance mass spectrometry to image various adrenocorticosteroids, including 18-oxocortisol, in adrenal tissue sections from 8 primary aldosteronism patients with APCC (cases 1-4), possible APCC-to-APA transitional lesions (case 5), and APA (cases 6-8). Further analyses by tandem mass spectrometry imaging allowed us to differentially visualize aldosterone from cortisone, which share identical mass-to-charge ratio value ( m/z). In conclusion, these advanced imaging techniques revealed that aldosterone and 18-oxocortisol coaccumulated within CYP11B2-expressing lesions. These imaging outcomes along with a growing body of aldosterone research led us to build a progressive development hypothesis of an aldosterone-producing pathology in the adrenal glands.