Masao Omura

The Adrenal Vein Sampling International Study (AVIS) for Identifying the Major Subtypes of Primary Aldosteronism

CONTEXT In patients who seek surgical cure of primary aldosteronism (PA), The Endocrine Society Guidelines recommend the use of adrenal vein sampling (AVS), which is invasive, technically challenging, difficult to interpret, and commonly held to be risky. OBJECTIVE The aim of this study was to determine the complication rate of AVS and the ways in which it is performed and interpreted at major referral centers. DESIGN AND SETTINGS The Adrenal Vein Sampling International Study is an observational, retrospective, multicenter study conducted at major referral centers for endocrine hypertension worldwide. PARTICIPANTS Eligible centers were identified from those that had published on PA and/or AVS in the last decade. MAIN OUTCOME MEASURE The protocols, interpretation, and costs of AVS were measured, as well as the rate of adrenal vein rupture and the rate of use of AVS. RESULTS Twenty of 24 eligible centers from Asia, Australia, North America, and Europe participated and provided information on 2604 AVS studies over a 6-yr period. The percentage of PA patients systematically submitted to AVS was 77% (median; 19-100%, range). Thirteen of the 20 centers used sequential catheterization, and seven used bilaterally simultaneous catheterization; cosyntropin stimulation was used in 11 centers. The overall rate of adrenal vein rupture was 0.61%. It correlated directly with the number of AVS performed at a particular center (P = 0.002) and inversely with the number of AVS performed by each radiologist (P = 0.007). CONCLUSIONS Despite carrying a minimal risk of adrenal vein rupture and at variance with the guidelines, AVS is not used systematically at major referral centers worldwide. These findings represent an argument for defining guidelines for this clinically important but technically demanding procedure.

Clinical characteristics of aldosterone-producing microadenoma, macroadenoma, and idiopathic hyperaldosteronism in 93 patients with primary aldosteronism.

Primary aldosteronism (PA) due to aldosterone-producing adenoma (APA) is a form of surgically curable secondary hypertension, and distinguishing APA from idiopathic hyperaldosteronism (IHA) is important for treatment. We made a differential diagnosis between APA and IHA using imaging tests such as adrenal CT and MRI as well as adrenal venous sampling (AVS) in all 93 cases of PA presenting at our institutions over the last decade. We identified 27 patients with aldosterone-producing microadenoma (APmicroA), all of whom could be diagnosed by AVS but not by the imaging tests. Then, we compared the clinical and roentgenological findings of these 27 patients with those of 42 patients with aldosterone-producing macroadenoma (APmacroA) and of 24 patients with IHA. Using surgically removed adrenal tissues, histopathological examinations and immunohistochemical analyses of steroidogenic enzymes were conducted. The findings for APmicroA were similar to those for APmacroA, except with respect to the diameter of the adrenal adenomas. Endocrinological and roentgenological findings for APmicroA were similar to those for IHA, but not to those for APmacroA. The rate of cure of hypertension was much greater in patients with APmicroA than in patients with APmacroA after the unilateral adrenalectomy (odds ratio, 4.0; p=0.028). In conclusion, it is important to accurately diagnose APmicroA, in which the laterality of the hyperproduction of aldosterone is only detectable by AVS, and to treat these patients by unilateral adrenalectomy in order to avoid long-term medical treatment and prevent hypertensive vascular complications.

Involvement of high density lipoprotein as substrate cholesterol for steroidogenesis by bovine adrenal fasciculo-reticularis cells

Adrenocorticosteroids are known to be synthesized from cholesterol which may arise from de novo synthesis or from the uptake of low-density lipoproteins (LDL) or high-density lipoproteins (HDL). LDL is reported to be a main substrate for corticosteroid synthesis by bovine adrenocortical cells, although the role of HDL, which is well known to be used for steroid biosynthesis in rat adrenals, is still obscure. Therefore, we examined the role of HDL in the regulation of corticosteroidogenesis in bovine adrenals in order to clarify whether or not HDL was selectively utilized for corticosteroid synthesis in vitro. The present data demonstrated that HDL and LDL increased cortisol production in a dose-dependent manner in bovine adrenocortical cells in vitro, and also that HDL cholesterol increased cortisol production significantly higher than LDL cholesterol did. Addition of adrenocorticotrophic hormone (ACTH) with HDL to the incubation media enhanced much higher cortisol production than that with LDL in short time incubation. The present data also demonstrated that uptake of 125I-HDL was significantly greater than that of 125I-LDL. Thus, HDL rather than LDL is thought to be the preferred lipoprotein as a source of steroidogenic substrate cholesterol in bovine adrenal fasciculo-reticularis cells.

Comparison of Cardiovascular Complications in Patients with and without KCNJ5 Gene Mutations Harboring Aldosterone-producing Adenomas

AIM Our objective was to evaluate the incidence of cardiovascular complications before and after unilateral adrenalectomy in patients with and without KCNJ5 gene mutations harboring aldosterone-producing adenoma (APA). METHODS A total of 108 APA patients were evaluated in the present study. We compared the clinical characteristics and laboratory findings according to the cardiovascular complications in the patients with or without KCNJ5 gene mutations harboring APA after excluding five APA patients with ATPase or CACNA1D gene mutations. RESULTS There were 75 and 28 APA patients with somatic mutations of KCNJ5 (p.G151R, p.L168R, p.E145Q, p.T158A or 157del) and no mutations, respectively. There were no double mutations in any of the subjects. The KCNJ5-mutated and wild type groups demonstrated similar advances in left ventricular hypertrophy prior to surgery, although the mutated group was significantly younger, with higher plasma and urine aldosterone levels, than the wild type group (48.2 vs. 55.8 (years old); p＜0.001, 436.0 vs. 247 (pg/mL); p＜0.001, 22.2 vs. 12.6 (μg/day); p=0.008). Both groups displayed postoperative improvements in hyperaldosteronism and hypertension. Moreover, the LV mass index (LVMI) significantly improved after surgery in the mutated group (p＜0.001), but not in the wild type group (p=0.256). A multiple linear regression analysis showed that an improvement in the LVMI was independently associated with KCNJ5 mutations and the plasma aldosterone level in that order (p=0.034, 0.050, respectively). CONCLUSION The present findings clearly demonstrated that KCNJ5 mutations are common among Japanese APA patients (frequency: 69.4%). In this study, the KCNJ5-mutated group demonstrated significant postoperative improvements in LVMI, possibly due to strong autonomous aldosterone production. Hence, it is necessary to precisely diagnose younger APA patients possessing a strong capacity for aldosterone production due to KCNJ5 gene mutations, as such cases may be easily complicated by cardiovascular events.

Chemoprevention of precursors to colon cancer by dehydroepiandrosterone (DHEA).

Although dehydroepiandrosterone (DHEA) is recognized as one of the major adrenal androgens, its precise physiological role in the human endocrine system remains to be elucidated. In particular, the effect of DHEA on carcinogenesis has not been fully characterized. We undertook this study to determine whether DHEA has a chemopreventative effect on the precursors of colon cancer in a murine model of azoxymethane (AOM)-induced aberrant crypt foci (ACF). The number of ACF was significantly decreased in mice treated with 0.4% (p < 0.001) and 0.8% DHEA (p < 0.001), but there were no significant differences between DHEA-treated and control mice in terms of the ACF size, 3-catenin expression or level of dysplasia. This is the first study of colon cancer carcinogenesis demonstrating that DHEA treatment can decrease the number of ACF without apparently modifying their malignant potential. These data strongly suggest that DHEA might be a potential chemopreventative agent against human colon cancer.

Effect of ACE gene on diabetic nephropathy in NIDDM patients with insulin resistance

We investigated the influence of the angiotensin-converting enzyme (ACE) gene on the onset and/or progression of diabetic nephropathy in 62 Japanese patients with non-insulin-dependent diabetes mellitus (NIDDM; type II diabetes). Because a number of factors are believed to be involved in the onset and/or progression of diabetic nephropathy, especially in patients with NIDDM, we selected the patients with well-matched risk factors, duration of disease, glycemic control, blood pressure, and others. All patients had normal renal function and none were receiving ACE inhibitors. Patients were divided into three groups according to albumin excretion rate (AER): group A, patients with an AER less than 15 microg/min (n = 29); group B, patients with an AER between 15 and 70 microg/min (n = 19); and group C, patients with an AER greater than 70 microg/min (n = 14). The glucose disposal rate was estimated using a euglycemic hyperinsulinemic clamp. We determined the mean glucose disposal rate in 132 patients with NIDDM (6.49 mg/kg/min). Patients with a glucose disposal rate less than the mean rate were considered to have a high degree of insulin resistance (n = 36). The presence of an insertion/deletion (I/D) polymorphism of the ACE gene was determined by the polymerase chain reaction method. Among patients with a high degree of insulin resistance, diabetic nephropathy was present in 2 of 11 patients with the II genotype of the ACE gene compared with 19 of 25 patients with the ID or DD genotype (P = 0.0024). The prevalence of diabetic nephropathy was greater in patients with both significant insulin resistance and the D allele (19 of 25) than in the remaining patients (14 of 37; odds ratio, 5.20). These results suggest that the ACE gene influences the onset and/or progression of diabetic nephropathy in patients with NIDDM with significant insulin resistance.

Case report: Nodule development from subcapsular aldosterone-producing cell clusters causes hyperaldosteronism

CONTEXT We previously reported that the human adrenal cortex remodels to form subcapsular aldosterone-producing cell clusters (APCCs). Some APCCs were recently found to carry aldosterone-producing adenoma (APA)-associated somatic mutations in ion channel/pump genes, which implied that APCCs produce aldosterone autonomously and are an origin of APA. However, there has been no report describing an APCC-to-APA transitional lesion. CASE DESCRIPTION A histological examination revealed unilateral multiple adrenocortical micronodules in the adrenals of two patients with primary aldosteronism (PA). Based on immunohistochemistry for aldosterone synthase, some of the micronodules were identified as possible APCC-to-APA transitional lesions (pAATLs; a tentative term used in this manuscript), which consisted of a subcapsular APCC-like portion and an inner micro-APA-like (mAPA-like) portion without an apparent histological border. Genomic DNA samples prepared from pAATL histological sections were analyzed by next-generation sequencing for the known APA-associated mutations. The mAPA-like portions from two of the three large pAATLs examined harbored mutations (KCNJ5 [p.G151R] in pAATL 3 and ATP1A1 [p.L337M] in pAATL 7), whereas their corresponding APCC-like portions did not, suggesting their role in the formation of mAPA. Another lesion carried novel mutations in ATP1A1 (p.Ile322_Ile325del and p.Ile327Ser) in both the mAPA-like and APCC-like portions, thereby supporting these portions having a clonal origin. CONCLUSION A novel aldosterone-producing pathology, pAATL that causes unilateral PA, was detected in the adrenals of two patients. Next-generation sequencing analyses of the large pAATLs suggested that the introduction of APA-associated mutations in the ion channel/pump genes may be involved in the development of mAPA from existing APCCs.

Clinical and Steroidogenic Characteristics of Aldosterone-Producing Adenomas With ATPase or CACNA1D Gene Mutations

OBJECT This comparative study clarified the clinical characteristics and in vitro steroidogenic activities of aldosterone-producing adenomas (APAs) harboring ATPase or CACNA1D gene mutations. DESIGN AND PATIENTS Genetic testing was performed on 159 unilateral APAs. Somatic ATPase and CACNA1D gene mutations were analyzed in 42 APA tissues without KCNJ5 gene mutations. RESULTS ATP1A1, ATP2B3, and CACNA1D mutations were detected in one, four, and four patients, respectively. Compared with patients without KCNJ5, ATPase, or CACNA1D mutations (wild type), ATPase mutations tended to have more severe hyperaldosteronism and smaller tumors; those with CACNA1D mutations had clinical characteristics and tumor sizes similar to those with wild-type genes. APAs with ATPase mutations were composed mainly of compact eosinophilic tumor cells, whereas CACNA1D mutations resulted in predominantly clear tumor cells. Aldosterone production in APA cells with ATP2B3 mutations were more responsive to dibutyryl cAMP, whereas those with CACNA1D mutations were more responsive to adrenocorticotropic hormone than the wild-type cells. CONCLUSION APAs with ATPase mutations demonstrated a potentially severe primary aldosteronism phenotype, whereas those with CACNA1D mutations displayed characteristics similar to wild-type APAs. The status of stimulated aldosterone production was also different according to the cell types, suggesting that the regulatory effects of adrenocorticotropic hormone on aldosterone synthesis could possibly vary according to the intracellular signaling involved in hormone production.

The possibility of resistant hypertension during the treatment of hypertensive patients.

Patients with poorly controlled hypertension despite taking at least three different kinds of anti-hypertensive drugs, including diuretics, are considered to have resistant hypertension (RH). The prevalence of RH was reported to be 13% in the Japanese J-HOME study. The incidences of RH in younger and older Japanese individuals should be prospectively investigated in the near future. RH is associated with poor outcomes and various cardiovascular events. In addition, it is frequently associated with older age, obesity, sleep apnea, long-term hypertension, diabetes, dyslipidemia, reduced renal function, microalbuminuria and left ventricular hypertrophy. Some cases of RH exhibit high levels of aldosterone and cortisol, suggesting that endocrine hypertension should be ruled out among RH patients. Carotid baroreceptor activation and renal sympathetic denervation have recently been developed as treatments for RH. In conclusion, we should consider the possibility of RH during the treatment of hypertensive patients who do not achieve appropriate blood pressure control, in order to avoid the early onset of fatal cardiovascular events and reduce medical costs.

Is primary aldosteronism rare or common among hypertensive patients

The worldwide prevalence of primary aldosteronism (PA) among unselected patients with hypertension is considered to be 10–15% (1, 2). However, there have always been wide variations in the reported prevalence of hyperaldosteronism. When Conn first described the syndrome, he estimated that about 20% of hypertensives had adrenal adenoma (3). In making this estimate, Conn used the unique combination of decreased or absent plasma renin activity (PRA) together with an increased secretion of aldosterone (Aldo) rather than hypokalemia as the initial indicator of PA. Unfortunately, their observation that PA occurred even in normokalemic subjects and Conn’s recommendation (4) that every patient with essential hypertension should undergo appropriate testing to exclude this entity were subsequently forgotten by most clinicians. The Italian group of Fogari et al. reported in this issue (5) that the prevalence of PA was 5.9% of their studied population, which consisted of 3,000 consecutive hypertensive patients (1,427 males and 1,573 females; aged 25 to 70 years) who were referred by general practitioners to their Hypertension Center between June 1999 and October 2002. Their patients presented between 8:00 AM and 9:00 AM after an overnight fast. Blood samples for the measurement of PRA, Aldo, sodium, potassium, and creatinine were obtained from patients who had been standing for 2 h (5). Their findings indicated that the standardized application of an aldosterone-renin ratio (ARR) >25 to unselected hypertensive patients, followed by i.v. saline loading as a confirmatory test, resulted in the detection of a large number of patients with PA (5.9% of the studied population), most of whom were normokalemic (24.8%) (5). We performed PA screening in 1,020 Japanese patients with hypertension, and detected the disorder in 6.0% of this cohort (6). As described above, the incidence rates ranged widely between 3% and 22%. Subjects for each study varied widely, and included both unselected hypertensives and/or patients referred to the hypertension unit. This variation is not in itself problematic, however, since the characteristics of patients previously used to establish the prevalence of PA also varied widely. Moreover, the criteria for screening PA among hypertensives, including the value of ARR, and confirmatory tests for definitively diagnosing PA, such as the saline infusion test, have varied among these reports. In a review involving 7 areas between 1981 and 2003, the incidence of PA was 6.6% (7), which was similar to what we reported (6%) (6, 8); internationally, the incidence of PA in hypertensive patients was estimated to be 6%, very similar to the result of Fogari et al. (5). Hiramatsu et al. (9) initially used this index of ARR for PA screening; antihypertensive agents were discontinued in the presence of a standard diet, and blood was collected in the standing position to compare ARR. This procedure facilitates PA screening, with a cut-off value of 40. To establish specific diagnostic criteria, conditions such as posture at blood collection (standing, supine, and sitting positions), diet (free, salt restricted), and antihypertensive agents (after treatment for a few weeks, no administration, and low-dose therapy permitted) must be standardized. Estimation of the ARR value is not always done as a routine procedure in all patients with hyper-