Unilateral adrenalectomy improves insulin resistance and diabetes mellitus in a patient with ACTH-independent macronodular adrenal hyperplasia

Clinical, pathophysiologic, genetic and therapeutic progress in Primary Bilateral Macronodular Adrenal Hyperplasia

Patients with primary bilateral macronodular adrenal hyperplasia (PBMAH) usually present bilateral benign adrenocortical macronodules at imaging and variable levels of cortisol excess. PBMAH is a rare cause of primary overt Cushing's syndrome, but may represent up to one third of bilateral adrenal incidentalomas with evidence of cortisol excess. The increased steroidogenesis in PBMAH is often regulated by various G-protein coupled receptors aberrantly expressed in PBMAH tissues; some receptor ligands are ectopically produced in PBMAH tissues creating aberrant autocrine/paracrine regulation of steroidogenesis. The bilateral nature of PBMAH and familial aggregation, led to the identification of germline heterozygous inactivating mutations of the ARMC5 gene, in 20-25% of the apparent sporadic cases and more frequently in familial cases; ARMC5 mutations/pathogenic variants can be associated with meningiomas. More recently, combined germline mutations/pathogenic variants and somatic events inactivating the KDM1A gene were specifically identified in patients affected by GIP-dependent PBMAH. Functional studies demonstrated that inactivation of KDM1A leads to GIP-receptor (GIPR) overexpression and over or down-regulation of other GPCRs. Genetic analysis is now available for early detection of family members of index cases with PBMAH carrying identified germline pathogenic variants. Detailed biochemical, imaging, and co-morbidities assessment of the nature and severity of PBMAH is essential for its management. Treatment is reserved for patients with overt or mild cortisol/aldosterone or other steroid excesses taking in account co-morbidities. It previously relied on bilateral adrenalectomy; however recent studies tend to favor unilateral adrenalectomy, or less frequently, medical treatment with cortisol synthesis inhibitors or specific blockers of aberrant GPCR.

A 30-year single-center experience of unilateral adrenalectomy for primary bilateral macronodular adrenal hyperplasia

OBJECTIVE

The aim of this study is to assess the short- and long-term outcomes of unilateral adrenalectomy (UA) in patients with primary bilateral macronodular adrenal hyperplasia (PBMAH).

METHODS

We conducted a retrospective study of 124 patients with PBMAH who underwent UA.

RESULTS

124 adrenalectomies were performed without intraoperative mortality. After a median duration of 28.5months (1∼165months, mean 51.92 ± 47.21 months), 116 patients were available for follow-up. Cushingoid features remitted in 70.8% (43/65) of patients with overt Cushing's Syndrome (CS). Hypertension and diabetes mellitus improved in 82.3% (79/96) and 69.0% (29/42) of patients respectively. 6.0% (7/116) of patients developed glucocorticoid insufficiency postoperatively, and all resolved during the follow-up. The mean 24h-UFC (reference range 12.3∼103.5μg/24h) decreased gradually from 456.02±422.33μg/24hr at baseline to 84.47±70.06μg/24hr within 3 months and then climbed progressively in some patients. 55.2% (64/116) had biochemical recurrence with/without symptom recurrence and 67.2% (43/64) of them received contralateral adrenalectomy. The median interval time of the second operation from the first UA was 24 months (1∼165months, mean 43.58 ± 44.54 months), and it took less time in patients with overt CS (median 22 months, 1∼165 months, mean 37.24 ± 41.85 months) than those without overt CS (median 72 months, 1∼144 months, mean 61.45 ± 46.73 months). Patients with overt CS had larger surgical-side or contralateral adrenal volume than that of patients without overt CS. Patients with contralateral adrenal volume larger than 33.54ml or with pre-operative UFC more than 216.08μg/24hr were more likely to have recurrence.

CONCLUSION

The efficiency of UA is transient for majority of patients, and the indications should be strictly limited to those with subclinical or milder CS. The successful UA patients still require close lifetime follow-up for recurrence of hypercortisolism.

Unilateral adrenalectomy partially improved hyperglycemia in a patient with primary bilateral macronodular adrenal hyperplasia

Primary bilateral macronodular adrenal hyperplasia (PBMAH) is characterized by bilateral multiple adrenal macro-nodules that often cause mild over-secretion of cortisol in the form of subclinical Cushing's syndrome. We herein describe a case, wherein unilateral adrenalectomy partially improved hyperglycemia in a patient with PBMAH and suggest the usefulness and limitations of this surgical strategy. A 64-year-old woman with type 2 diabetes had an incidental diagnosis of bilateral adrenal lesions. She had a family history of type 2 diabetes, and her HbA1c level was 8.9% under insulin therapy. She did not present with any symptoms associated with Cushing's syndrome. The basal cortisol level was in the normal range (12.0 μg/dL); however, the adrenocorticotropic hormone (ACTH) level was suppressed (2.1 pg/mL) and the serum cortisol level was not suppressed in the dexamethasone test. Computed tomography and magnetic resonance imaging showed bilateral adrenal macro-nodules and ¹³¹I-adosterol accumulated in the bilateral adrenal lesions. Collectively, she was diagnosed with subclinical Cushing's syndrome due to PBMAH complicated with diabetes mellitus, hypertension, and dyslipidemia. Laparoscopic left adrenalectomy was performed, and the pathologic findings were consistent with PBMAH. After unilateral adrenalectomy, serum cortisol levels decreased, and hypertension improved. Both HbA1c levels and insulin requirement also decreased, but insulin therapy was continuously needed. It should be noted that hyperglycemia may not be cured after successful surgery in a patient with PBMAH. Additional operation or medical therapy should be considered if unilateral adrenalectomy is unable to correct hypercortisolism in PBMAH patients.

Role of unilateral adrenalectomy in bilateral adrenal hyperplasias with Cushing's syndrome

Primary bilateral adrenocortical hyperplasias are rare forms of pituitary ACTH-independent Cushing's syndrome (CS). They are divided between primary bilateral macronodular adrenal hyperplasia (PBMAH) and micronodular adrenal hyperplasia (MiBAH), which is subdivided in primary pigmented nodular adrenocortical disease (PPNAD) and isolated micronodular adrenocortical disease (i-MAD). One of the most debated aspects surrounding these entities is their most appropriate therapy. Although bilateral adrenalectomy (BA) has previously been the most utilized therapy for patients with overt CS, recent studies have indicated that unilateral adrenalectomy (UA) can be effective in patients with PBMAH and some with MiBAH with fewer long-term side effects. Medical therapies can also be used for bridging to surgery or rarely in the long-term for these patients. We review the various degrees of CS resulting from PBMAH and MiBAH, with a special focus on their respective therapies including UA, taking into account the recent pathophysiological and genetics findings.

Unilateral Adrenalectomy for Primary Bilateral Macronodular Adrenal Hyperplasia: Analysis of 71 Cases

Objective Primary bilateral macronodular adrenal hyperplasia (PBMAH) is characterized by benign bilateral enlarged adrenal masses, causing Cushing’s syndrome (CS). The aim of the current article is to define the role of unilateral adrenalectomy (UA) in treating patients with CS related to PBMAH.

Methods A PubMed database search was conducted to identify articles reporting UA to treat PBMAH. We also report cases of PBMAH from our medical center treated by UA.

Results A total number of 71 cases of PBMAH (62 cases reported in the literature and 9 cases from our center) are presented. Most patients were women (73.2%) and most UA involved the left side (64.3%). In most cases, the resected gland was the larger one. Following UA, 94.4% of cases had remission of hypercortisolism. Recurrence rate of CS was 19.4% and hypoadrenalism occurred in 29.6%. After UA, when the size of the remained adrenal gland was equal or greater than 3.5 cm, CS persisted in 21.4% of cases, and recurrence occurred in 27.3% of cases (after 20±9.2 months). However, when the size of the remained gland was less than 3.5 cm, CS resolved in all cases and recurrence occurred in 21.2% of cases after a long period (65.6±52.1 months). High levels of urinary free cortisol (UFC) were not correlated with post-surgical CS recurrence or persistence.

Conclusions UA leads to beneficial outcomes in patients with CS related to PBMAH, also in cases with pre-surgical elevated UFC or contralateral large gland.

Adrenal Surgery for Cushing's Syndrome: An Update

Recent advances in the molecular pathogenesis and the natural history of Cushing's syndrome have improved the understanding of the management of this disease. The long-term efficacy of several cortisol-lowering medical treatments is currently under evaluation. However, adrenalectomy is a safe option for the treatment of patients affected by Cushing's syndrome. Unilateral adrenalectomy is the gold standard for treatment of adrenocortical adenomas associated with hypercortisolism. Bilateral adrenalectomy has been widely used in the past as definitive treatment of bilateral macronodular hyperplasia and persistent or recurrent Cushing's disease. The indication and the potential applications of this technique have been recently critically analyzed.

Adrenal (131)I-6β-iodomethylnorcholesterol scintigraphy in choosing the side for adrenalectomy in bilateral adrenal tumors with subclinical hypercortisolemia

Purpose

Adrenal scintigraphy with 131I-6β-iodomethylnorcholesterol is considered by several authors the gold standard for assessing tumors with subclinical hypercortisolemia. However, most of the described series consist mainly of cases with unilateral lesions. The aim of our study was to assess whether scintigraphy is useful in choosing the adrenalectomy side in the case of bilateral adrenal tumors with subclinical hypercortisolemia.

Methods

The study focused on 15 consecutive patients with benign bilateral adrenal tumors and subclinical hypercortisolemia. The scintigraphy with 131I-6β-iodomethylnorcholesterol was performed. Fourteen patients underwent unilateral adrenalectomy; the gland with predominant uptake on scintigraphy was removed. Cortisol and ACTH concentrations were measured one and six months after surgery. Post-dexamethasone cortisolemia was assessed six months after surgery. To date, the patients have been under postoperative observation for 1–4 years.

Results

Four patients showed unilateral uptake of radiotracer, and nine patients showed predominant accumulation of radiotracer in one of the adrenal glands. The smaller tumor was predominant in 2 cases. Percentage of activity on the predominant side correlates positively with the difference between tumors’ diameters. Unilateral uptake of radiotracer predicts long-lasting postoperative insufficiency of the second adrenal gland. Excision of predominating tumor led to cessation of hypercortisolemia in all patients.

Conclusions

The corticoadrenal scintigraphy is useful in choosing the side for operation in the case of bilateral adrenal tumors with subclinical hypercortisolemia.

Biochemical and clinical benefits of unilateral adrenalectomy in patients with subclinical hypercortisolism and bilateral adrenal incidentalomas

OBJECTIVE

The treatment of subclinical hypercortisolism in patients with bilateral adrenal incidentalomas (AI) is debatable. We aimed to compare the biochemical and clinical outcome of unilateral adrenalectomy vs a conservative approach in these patients.

DESIGN

Retrospective study.

METHODS

The study included 33 patients with bilateral AI; 14 patients underwent unilateral adrenalectomy of the largest lesion (surgical group), whereas 19 patients were followed up (follow-up group). At baseline and at each follow-up visit, we measured 0800 h plasma ACTH, midnight serum cortisol (MSF), 24-h urinary-free cortisol (UFC) and serum cortisol following a standard 2-day low-dose-dexamethasone-suppression test (LDDST). We evaluated the following comorbidities: arterial hypertension, impaired glucose tolerance or diabetes mellitus, dyslipidemia and osteoporosis.

RESULTS

Baseline demographic, clinical characteristics and the duration of follow-up (53.9±21.3 vs 51.8±20.1 months, for the surgical vs the follow-up group) were similar between groups. At the last follow-up visit the surgical group had a significant reduction in post-LDDST cortisol (2.4±1.6 vs 6.7±3.9 μg/dl, P=0.002), MSF (4.3±2 vs 8.8±4.6 μg/dl, P=0.006) and 24-h UFC (50.1±21.1 vs 117.9±42.4 μg/24 h, P=0.0007) and a significant rise in mean±s.d. morning plasma ACTH levels (22.2±9.6 vs 6.9±4.8 pg/ml, P=0.002). Improvement in co-morbidities was seen only in the surgical group, whereas no changes were noted in the follow-up group.

CONCLUSIONS

Our early results show that removal of the largest lesion offers significant improvement both to cortisol excess and its metabolic consequences, without the debilitating effects of bilateral adrenalectomy. A larger number of patients, as well as a longer follow-up, are required before drawing solid conclusions.

An analysis of different therapeutic options in patients with Cushing's syndrome due to bilateral macronodular adrenal hyperplasia: a single-centre experience

CONTEXT

Bilateral macronodular adrenal hyperplasia (BMAH) is a rare form of Cushing's syndrome (CS). A variety of in vivo tests to identify aberrant receptor expression have been proposed to guide medical treatment. Unilateral adrenalectomy (UA) may be effective in selected patients, but little is known about recurrence during follow-up.

OBJECTIVE

To describe a series of patients with BMAH and CS treated by different approaches, with a particular focus on the benefit of UA.

DESIGN AND PATIENTS

We retrospectively assessed 16 patients with BMAH and CS (11 females, five males), analysing the in vivo cortisol response to different provocative tests. Twelve of the 16 patients underwent UA and were monitored over the long term.

RESULTS

Based on in vivo test results, octreotide LAR or propranolol was administered in one case of food-dependent CS and two patients with a positive postural test. A significant improvement in biochemical values was seen in all patients but with limited clinical response. UA was performed in 12 patients, producing long-term remission in three (106 ± 28 months; range: 80-135), recurrence in eight (after 54 ± 56 months; range 12-180) and persistence in one other. Four patients subsequently underwent contralateral adrenalectomy for overt CS, one received ketoconazole, and four other patients remain under observation for subclinical CS.

CONCLUSIONS

Medical treatment based on cortisol response to provocative tests had a limited role in our patients, whereas UA was useful in some of them. Although recurrence is likely, the timing of onset is variable and close follow-up is mandatory to identify it.

Long-Term Outcome of Bilateral Laparoscopic Adrenalectomy Measured by Disease-Specific Questionnaire in a Unique Group of Patients with Cushing's Syndrome

BACKGROUND

Laparoscopic bilateral adrenalectomy (LBA) is recommended for patients with bilateral adrenal disease and occult or unresectable ectopic Cushing's syndrome (CS). There are limited data on long-term outcomes after LBA, partly due to the lack of disease-specific tools for the measurement of impact on patients' health and quality of life.

METHODS

We used a disease-specific questionnaire covering all major clinicopathologic characteristics of CS. We compared the outcome from LBA to a control group of 60 patients who had thyroidectomy (matched for age, gender, and time of surgery, 2:1 control-to-CS).

RESULTS

Twenty-eight patients (20 women and 8 men) underwent LBA for CS. Of them, 24 patients (86 %) provided responses to our questionnaire. Ninety-two percent of patients' responses indicated a significant improvement of general Cushing's physical features with complete resolution reported in 59 % of responses. Significant improvement of associated biochemical abnormalities and comorbidities was reported in 83 % of patients' responses including complete reversal in 58 %. Significant improvement in emotional-behavioral symptoms was reported in 84 % of patients' responses with complete recovery in 53 %. All patients expressed satisfaction with LBA and significant improvement in their general health and self-reported quality of life. All of the improvements after LBA were statistically significant compared with the control group.

CONCLUSIONS

Our disease-specific questionnaire enables a clearer understanding of the association between the clinical, metabolic, and emotional-behavioral features of CS, its treatment with LBA, and long-term impact on patient-reported quality of life. This disease-specific questionnaire may be useful for future studies in patients with CS.

Classification, diagnosis and treatment of ACTH-independent macronodular adrenal hyperplasia

ACTH-independent macronodular adrenal hyperplasia (AIMAH) is a distinctive subtype of Cushing's syndrome (CS), with different clinical manifestations according to the level of serum cortisol. Based on clinical manifestations and serum cortisol, we divide AIMAH into three types, subclinical AIMAH, clinical AIMAH and high-risk AIMAH, with varied treatment methods being adapted to different subtypes. At the same time, we describe 3 patients who represent these subtypes of this disease, and review some cases of AIMAH which have been previously reported in the English literature. To our knowledge, this is the first article discussing classification, diagnosis and treatment of this disease and should be useful for future therapy of AIMAH.

Successful treatment for adrenocorticotropic hormone-independent macronodular adrenal hyperplasia with laparoscopic adrenalectomy: a case series

Introduction

Adrenocorticotropic hormone-independent macronodular adrenal hyperplasia, characterized by bilateral macronodular adrenal hypertrophy and autonomous cortisol production, is a rare cause of Cushing’s syndrome. Bilateral adrenalectomy is considered the standard treatment for adrenocorticotropic hormone-independent macronodular adrenal hyperplasia but obliges the patient to receive lifetime steroid replacement therapy subsequently, and may increase the patient’s risk of adrenal insufficiency. These circumstances require surgeons to carefully consider operative strategies on an individual basis.

Case presentation

We performed successful laparoscopic adrenalectomy on four patients with adrenocorticotropic hormone-independent macronodular adrenal hyperplasia. Computed tomography scans showed bilateral adrenal enlargement in all patients. Case 1: a 56-year-old Japanese woman presented with obvious Cushing’s symptoms during treatment for diabetes mellitus and hypertension. Case 2: a 37-year-old Japanese man also presented with Cushing’s symptoms during treatment for diabetes mellitus and hypertension. These patients were diagnosed as Cushing’s syndrome caused by adrenocorticotropic hormone-independent macronodular adrenal hyperplasia based on endocrinologic testing, and underwent bilateral laparoscopic adrenalectomy. Case 3: an 80-year-old Japanese woman was hospitalized due to unusual weight gain and heightened general fatigue, and was diagnosed as Cushing’s syndrome caused by adrenocorticotropic hormone-independent macronodular adrenal hyperplasia. She underwent unilateral laparoscopic adrenalectomy due to high operative risk. Case 4: a 66-year-old Japanese man was discovered to have bilateral adrenal tumors on medical examination. He did not have Cushing’s symptoms and was diagnosed as subclinical Cushing’s syndrome due to suppressed adrenocorticotropic hormone serum levels and loss of cortisol circadian rhythm without abnormal levels of serum cortisol. He underwent unilateral laparoscopic adrenalectomy. During follow-up, serum cortisol levels were within the normal range in all cases, and serum adrenocorticotropic hormone levels were not suppressed. Further, cases with Cushing’s syndrome experienced clinical improvement.

Conclusions

We were able to effectively treat adrenocorticotropic hormone-independent macronodular adrenal hyperplasia in patients with obvious Cushing’s symptoms by laparoscopic bilateral adrenalectomy, which promptly improved symptoms. Further, unilateral adrenalectomy was effective for treating an older patient at high operative risk and a patient with subclinical Cushing’s syndrome.

Do patients with type 2 diabetes mellitus have an increased prevalence of Cushing's syndrome?

Many clinical features are common for patients with type 2 diabetes mellitus (T2DM) and Cushing's syndrome (CS) such as central obesity, hypertension and dyslipidaemia. Patients with CS often have T2DM. Because T2DM is much more frequent than CS, it is possible that some patients with T2DM have increased production of cortisol and thus represent patients with CS. The aim of this review was to evaluate the prevalence of CS in patients with T2DM. A search was performed in PubMed and Medline. We found seven prospective studies, two case-control studies and two cross-sectional studies. The difficulties in diagnosing subclinical CS is discussed. The most frequent tests for diagnosing CS, late-night salivary cortisol, 1-mg dexamethasone suppression test and urinary free cortisol are discussed and put in relation to the results of the literature found. The observed prevalence of CS in patients with T2DM varies widely between the different studies, ranging from 0-9.4%. This may be due to patient selection, differences in test methodology (including choice of test), cutoff values and different cortisol assays. The true prevalence of CS in T2DM has not been determined. We need more studies investigating the prevalence of CS in T2DM patients. There is a need for developing more specific tests for diagnosing CS in patients with only slightly elevated cortisol secretion and subclinical CS. We suggest that examination for hypercortisolism should only be performed in T2DM patients with a cushingoid appearance and hypertension or truncal obesity or dyslipidaemia.

Usefulness and limitations of unilateral adrenalectomy for ACTH-independent macronodular adrenal hyperplasia in a patient with poor glycemic control

Adrenocorticotropic hormone (ACTH)-independent macronodular adrenal hyperplasia (AIMAH) is a rare disease which causes Cushing's syndrome. Bilateral adrenalectomy has been recommended as the treatment of choice for AIMAH. However, bilaterally adrenalectomized patients require lifelong steroid replacement therapy. Therefore, an increasing number of patients have undergone unilateral adrenalectomy for AIMAH. We report a case of AIMAH due to refractory diabetes in whom unilateral adrenalectomy initially yielded good diabetes control, but in whom poor glycemic control developed after 5 years, requiring eventual additional contralateral adrenalectomy. In elderly patients with AIMAH, one-stage bilateral adrenalectomy may be the treatment of choice.

Unilateral adrenalectomy can be an alternative therapy for infantile onset Cushing' s syndrome caused by ACTH-independent macronodular adrenal hyperplasia with McCune-Albright syndrome

We report herein the case of a 1-year-old boy with McCune-Albright syndrome (MAS) who presented with infantile-onset Cushing' s syndrome caused by ACTH independent macronodular adrenal hyperplasia (AIMAH). Abdominal CT, MRI, and adrenal scintigraphy with (131)I-adosterol identified bilateral adrenal involvement with the left adrenal gland being larger and functionally more active. Unilateral adrenalectomy of the left gland was performed and ameliorated many clinical symptoms, such as Cushingoid appearance and height restriction, and it also normalized many endocrinological data, such as diurnal rhythms of ACTH and cortisol, ACTH and cortisol responses to CRH, and urinary 24 hr free cortisol. Glucocorticoid was replaced for the first 1 year and 6 months after the operation. One adrenal crisis episode occurred at 3 weeks after the operation, but none have occurred since. These results suggest that unilateral adrenalectomy of the larger gland can be an alternative therapy for infantile onset Cushing' s syndrome caused by AIMAH with MAS, when asymmetric involvement is evident and the smaller gland is not markedly enlarged.

Familial vasopressin-sensitive ACTH-independent macronodular adrenal hyperplasia (VPs-AIMAH): clinical studies of three kindreds

OBJECTIVE

Cushing's syndrome due to familial ACTH-independent macronodular adrenal hyperplasia (AIMAH) has been reported in small kindreds. In vasopressin-sensitive AIMAH (VPs-AIMAH), VP stimulates an aberrant, ACTH-independent increase in cortisol. The aims of this study were to (i) delineate the preclinical phenotype of VPs-AIMAH in a three-generation kindred (AIMAH-01) and two smaller kindreds (AIMAH-02 and AIMAH-03) and (ii) investigate the aetiology of VP sensitivity in AIMAH-01.

DESIGN

Clinical studies of three kindreds for adrenal tumours or early Cushing's and molecular studies of adrenal tumours (AIMAH-01).

PATIENTS

Thirty-three individuals, from three kindreds, were screened for perturbations of the hypothalamic-pituitary-adrenal axis or adrenal tumours.

MEASUREMENTS

Patients underwent clinical, biochemical and adrenal imaging investigations. Evaluation included low-dose (1 IU/70 kg) VP stimulation. Adrenal VP receptor (AVPR1A, AVPR1B, AVPR2) expression (AIMAH-01) was assessed using RT-PCR and immunohistochemistry (IHC). IHC for VP was also performed.

RESULTS

AIMAH-01 had three siblings with Cushing's, and four individuals with suppressed ACTH/aberrant VP responses and/or adrenal nodules. In AIMAH-02, a father and son were affected. AIMAH-03 had three siblings with Cushing's. RT-PCR showed adrenal overexpression of AVPR1A and AVPR1B. IHC detected AVPR1A. The adrenal tumour from one patient also stained weakly for VP and AVPR2.

CONCLUSION

Adrenal nodules, suppressed ACTH and increased VP sensitivity may represent preclinical disease, allowing early detection, and treatment, of affected individuals. In AIMAH-01, increased VP sensitivity may be due to adrenal VP receptor overexpression. In these kindreds, VPs-AIMAH is familial, and autosomal dominant inheritance is most likely.

Glucocorticoids produce whole body insulin resistance with changes in cardiac metabolism

Insulin resistance is viewed as an insufficiency in insulin action, with glucocorticoids being recognized to play a key role in its pathogenesis. With insulin resistance, metabolism in multiple organ systems such as skeletal muscle, liver, and adipose tissue is altered. These metabolic alterations are widely believed to be important factors in the morbidity and mortality of cardiovascular disease. More importantly, clinical and experimental studies have established that metabolic abnormalities in the heart per se also play a crucial role in the development of heart failure. Following glucocorticoids, glucose utilization is compromised in the heart. This attenuated glucose metabolism is associated with altered fatty acid supply, composition, and utilization. In the heart, elevated fatty acid use has been implicated in a number of metabolic, morphological, and mechanical changes and, more recently, in "lipotoxicity". In the present article, we review the action of glucocorticoids, their role in insulin resistance, and their influence in modulating peripheral and cardiac metabolism and heart disease.

Clinical and Subclinical ACTH-Independent Macronodular Adrenal Hyperplasia and Aberrant Hormone Receptors

ACTH-independent macronodular adrenal hyperplasia (AIMAH) is a very rare cause of endogenous Cushing's syndrome (CS). In this review, the clinical characteristics, the pathophysiology, and the management of AIMAH are described. AIMAH typically presents with overt CS, but subclinical oversecretion of cortisol has been increasingly described. The diagnosis is suspected by adrenal nodular enlargement on conventional imaging following the demonstration of ACTH-independent hypercortisolism. Final diagnosis is established by histological examination of the adrenal tissue. Bilateral adrenalectomy is the treatment of choice but unilateral adrenalectomy has been proposed in selected cases. In patients with subclinical CS, the decision to treat should be individualized. The pathophysiology of this condition has begun to be elucidated in recent years. Diverse aberrant membrane-bound receptors expressed in a non-mutated form in the adrenal gland have been found to be implicated in the regulation of steroidogenesis in AIMAH. When systematically screened, most patients with AIMAH and CS or subclinical CS exhibit an in vivo aberrant cortisol response to one or various ligands suggesting the presence of aberrant adrenal receptors. A protocol designed to screen patients for the presence of these aberrant receptors should be undertaken in all patients with AIMAH. The identification of these receptors provides the potential for novel pharmacological therapies by suppressing the endogenous ligands or blocking the receptor with specific antagonists.

Bilateral adrenal Cushing's syndrome: macronodular adrenal hyperplasia and primary pigmented nodular adrenocortical disease

Corticotropin (ACTH)-independent bilateral macronodular adrenal hyperplasia (AIMAH) and primary pigmented nodular adrenocortical disease (PPNAD) are responsible for approximately 10% of adrenal Cushing's syndrome. AIMAH also can be present as subclinical bilateral incidentalomas in sporadic or familial forms. Diverse aberrant hormone receptors have been found to be implicated in the regulation of steroidogenesis and pathophysiology of AIMAH. PPNAD can be found alone or in the context of Carney complex, a multiple endocrine neoplasia syndrome. Additionally, it can be secondary to mutations of type 1 alpha-regulatory subunit of cAMP-dependent protein kinase A (PRKARIA). Strategies for the investigation and treatment of AIMAH and PPNAD are discussed.

Hiperplasia adrenal macronodular independente de ACTH (AIMAH): aspectos clínicos e moleculares

A AIMAH é caracterizada pela presença de macronódulos em ambas as adrenais, na ausência da estimulação do ACTH. Habitualmente, as manifestações clínicas aparecem somente após várias décadas de vida, provavelmente em função da baixa atividade esteroidogênica do tecido hiperplásico. Entretanto, em indivíduos assintomáticos cuja AIMAH foi descoberta acidentalmente, o eixo HHA já se encontra alterado. Estudos têm demonstrado que, na maioria dos casos de AIMAH, a secreção de cortisol é regulada de modo "aberrante" por hormônios como o GIP, AVP, catecolaminas, LH/hCG e serotonina, através de seus respectivos receptores, ectópicos ou eutópicos, porém aberrantemente acoplados à esteroidogênese. Os mecanismos moleculares responsáveis pela expressão ectópica dos receptores hormonais e/ou de seu acoplamento anormal à esteroidogênese adrenal ainda são pouco conhecidos. Embora a expressão aberrante destes receptores hormonais possa desempenhar um papel importante na iniciação da proliferação celular aumentada, bem como na esteroidogênese, é provável que eventos genéticos adicionais ocorram, envolvendo a regulação do ciclo celular, adesão e transcrição. Mutações no gene GNAS1 não associadas à síndrome de McCune-Albright podem ser encontradas em raros casos de AIMAH. Em alguns casos, a presença de receptor hormonal aberrante abre novas possibilidades de tratamento farmacológico específico do hipercortisolismo, seja isolado ou associado à adrenalectomia unilateral.