A case of unilateral adrenal hyperplasia: the diagnostic dilemma of hyperaldosteronism

Primary hyperaldosteronism: a case of unilateral adrenal hyperplasia with contralateral incidentaloma

Primary hyperaldosteronism is one of the most common causes of secondary hypertension but clear differentiation between its various subtypes can be a clinical challenge. We report the case of a 37-year-old African-American woman with refractory hypertension who was admitted to our hospital for palpitations, shortness of breath and headache. Her laboratory results showed hypokalaemia and an elevated aldosterone/renin ratio. An abdominal CT scan showed a nodule in the left adrenal gland but adrenal venous sampling showed elevated aldosterone/renin ratio from the right adrenal vein. The patient began a new medical regimen but declined any surgical options. We recommend clinicians to maintain a high level of suspicion to consider the less common subtypes of primary hyperaldosteronism, especially given the fact that the management greatly varies.

Adrenal histologic findings show no difference in clinical presentation and outcome in primary hyperaldosteronism

BACKGROUND

Primary hyperaldosteronism is most commonly due to a solitary cortical adenoma. Thus, some surgeons have suggested a subtotal adrenalectomy is a reasonable approach when a mass can be identified. On the other hand, adrenal vein sampling (AVS) is being used more frequently to distinguish patients with unilateral disease for adrenalectomy, even if a discrete mass is not identified on axial imaging. In these cases, surgical pathology may reveal a cortical adenoma, a cortical adenoma with hyperplasia, or cortical hyperplasia. The goal of this study was to compare the presentation and outcome among patients undergoing adrenalectomy and found to have different histologic features.

METHODS

We performed a retrospective analysis of 136 patients with primary hyperaldosteronism. A total of 95 patients had an adrenalectomy for unilateral disease. The preoperative clinical and laboratory, and postoperative outcome of the three aforementioned histologic groups were compared.

RESULTS

A total of 95 patients underwent an adrenalectomy. We found no significant difference in age, gender, body mass index, duration of hypertension, number of antihypertensive medications, serum aldosterone level, serum renin level, or adrenal vein sampling ratios among the three histologic categories. We also found no significant difference among the three categories in postoperative cure rate.

CONCLUSION

The rate of unilateral hyperplasia in patients with primary hyperaldosteronism (16%) is likely higher than previously reported, which may be due to the increasing use of AVS. The clinical presentation and outcome of patients regardless of the histologic findings are similar. Our data also suggests that subtotal adrenalectomy would not be appropriate in patients with primary hyperaldosteronism.

Primary aldosteronism: results of adrenalectomy for nonsingle adenoma

BACKGROUND

Historically, treatment of confirmed primary aldosteronism has been adrenalectomy for unilateral adenoma; bilateral hypersecretion is treated medically. Increasingly, we use adrenal venous sampling (AVS) to define unilateral hypersecretion. Histology of glands resected based on AVS often reveals multiple nodules or hyperplasia. The aim of this study was to compare patients with multiple nodules or hyperplasia with those with single adenoma with regard to cure, preoperative imaging, AVS ratio, and biochemical evaluation to determine if a nonsingle adenoma (NSA) process could be predicted to impact extent of adrenalectomy.

STUDY DESIGN

This was a retrospective study reviewing a single-institutional surgical experience at a tertiary academic center from 1993 to 2008, during which 215 patients with primary aldosteronism underwent unilateral adrenalectomy based on imaging of a single adenoma (normal contralateral gland) or AVS ratios. Histology included single adenoma versus NSA; cure was defined as normal immediate postoperative plasma or urine aldosterone level, normal aldosterone:renin ratio, or normotension without antihypertensive medications.

RESULTS

Follow-up (mean 13 months, range 0 to 185 months) was available for 167 patients: 132 (79%) single adenoma and 35 (21%) NSA. All 35 patients with NSA and 128 patients (97%) with single adenoma were cured. Imaging studies correctly predicted NSA in 29% and 57% when combined with AVS. Identifying patients with NSA preoperatively was impossible biochemically: mean serum and urinary aldosterone levels and AVS ratios were not different than those of the single adenoma group.

CONCLUSIONS

Twenty-one percent of patients had NSA, all cured by unilateral adrenalectomy. No preoperative evaluation reliably predicted NSA. Therefore, total unilateral adrenalectomy was safest given the potential for incomplete resection with partial adrenalectomy. Accurate AVS is highly predictive of cure irrespective of the unilateral adrenal histology.

Clinical Use of Laboratory Tests for the Identification of Secondary Forms of Arterial Hypertension

The prevalence of secondary hypertension can be underestimated if appropriate tests are not performed. The importance of selecting patients with a high pre-test probability of secondary forms of hypertension is first discussed. The laboratory tests currently used for seeking a cause of hypertension are critically reviewed, with emphasis on their operative features and limitations. Strategies to identify primary aldosteronism, the most frequent form of secondary hypertension, and to determine its unilateral or bilateral causes are described. Treatment entails adrenalectomy in unilateral forms, and mineralocorticoid receptor blockade in bilateral forms. Renovascular hypertension is also a common, curable form of hypertension, that should be identified as early as possible to avoid the onset of cardiovascular target organ damage. The tests for its confirmation or exclusion are discussed. The various tests available for the diagnosis of pheochromocytoma, which is much rarer than the above but extremely important to identify, are also described, with emphasis on recent developments in genetic testing. Finally, the tests for diagnosing some rarer monogenic forms and other renal and endocrine causes of arterial hypertension are explored.

Primary Hyperaldosteronism Secondary to Unilateral Adrenal Hyperplasia: an Unusual Cause of Surgically Correctable Hypertension. A review of 30 cases

INTRODUCTION

Unilateral adrenal hyperplasia (UAH) is a rare, surgically correctable cause of primary hyperaldosteronism (PH). We report 2 cases and review the literature for cases of PH secondary to UAH successfully treated via surgery.

METHODS

Two cases of UAH treated at our institution were retrospectively reviewed. In addition, we reviewed 28 cases of UAH previously reported in the English literature.

RESULTS

Median patient age was 49 (range: 10-62) years, with a male to female ratio of 1.7:1. All patients were hypertensive, with a median preoperative systolic and diastolic blood pressure of 170 (range: 135-250) mmHg and 110 (range: 75-140) mmHg, respectively. Most patients were hypokalemic, with a median serum potassium level of 2.8 (range: 1.4-3.9) mmol/l. Ten out of 13 patients (77%) who underwent postural studies had a decrease or no change in the plasma aldosterone level, suggesting a unilateral source of hyperaldosteronism, and 9/17 patients (53%) who underwent a computed tomography (CT) scan were correctly localized. Twelve patients underwent adrenal scintigraphy with or without dexamethasone suppression, of whom 6 (50%) were correctly localized. In 1 patient, adrenal scintigraphy demonstrated localization to the opposite gland. Adrenal venous sampling (AVS) was performed in 22 patients and successfully localized the lesion in all the patients. At a median follow-up of 12 (range: 3-96) months postsurgery, 47% of patients (14/30) were completely cured of their hypertension and 50% (15/30) had improved control. All 30 patients were cured of hypokalemia.

CONCLUSION

Although the existence of UAH remains controversial, it is increasingly accepted as a unique pathologic entity and has an excellent outcome after unilateral adrenalectomy.

Surgically correctable hypertension caused by primary aldosteronism

Surgically correctable forms of primary aldosteronism are generally held to be less common than forms requiring medical therapy. However, with the availability of improved diagnostic techniques and the adoption of a systematic and thorough diagnostic work-up they can be identified more commonly than expected. Adrenal vein sampling (AVS) for measurement of cortisol and aldosterone has emerged as the 'gold standard' diagnostic test for identifying unilateral causes of primary aldosteronism that are amenable to surgical cure. Adrenalectomy can provide long-term normalisation of blood pressure and correction of primary aldosteronism in about 55% of patients with an aldosterone-producing adenoma and can markedly ameliorate blood pressure control in the rest. This chapter summarises the diagnostic work-up suggested for identifying these forms and examines the other diseases mimicking mineralocorticoid excess that enter into the differential diagnosis of surgically curable primary aldosteronism.

Adrenal Vein Sampling: How to Make It Quick, Easy, and Successful

Adrenal vein sampling has a reputation as a difficult procedure. However, it is being performed more frequently at some institutions due to the realization that primary aldosteronism is more common than previously believed. At the author's institution, adrenal vein sampling with computed tomographic (CT) and laboratory correlation has been performed more than 800 times in the past 10 years. Adrenal vein sampling is used to determine whether autonomous hormone production is unilateral or bilateral; unilateral secretion can be treated with surgery. The venous drainage of each adrenal gland is predominantly via a central vein. Recognition of the right adrenal vein is the crux of adrenal vein sampling. CT is useful in planning adrenal vein sampling by demonstrating the anatomy and positions of the adrenal veins. A small amount of contrast material is injected gently and slowly into the adrenal vein; it is not necessary to perform formal venography to outline the entire gland. To confirm that the vein is draining the majority of adrenal cortical blood, the adrenal vein sample should have a significantly higher level of cortisol than a peripheral sample. Adrenal glands that are producing aldosterone demonstrate an aldosterone-cortisol ratio that is higher than the peripheral value.

A Case of Primary Aldosteronism Due to Unilateral Adrenal Hyperplasia

The case of a patient with primary aldosteronism due to unilateral adrenal hyperplasia (UAH) is reported. A 43-year-old man with an 8-year history of hypertension presented at our institution with hypokalemia, increased plasma aldosterone concentration (PAC), and suppressed plasma renin activity (PRA). An abdominal CT scan showed almost normal adrenal glands with slight enlargement in the left gland. 131I-Norcholesterol adrenal scintigraphy under dexamethasone suppression showed bilaterally decreased uptake. To rule out idiopathic hyperaldosteronism, an adrenal vein sampling before and after ACTH stimulation was performed and a left-sided lateralization of PAC was observed. A left adrenalectomy was performed, and the patient had a good clinical and biochemical response. Micronodular hyperplasia was discovered in the adrenal gland histologically, and in the immunohistochemical analysis, positive staining for 3beta-hydroxysteroid dehydrogenase in micronodular lesions confirmed the diagnosis of UAH. Although UAH is a rare subset of primary aldosteronism, it is surgically correctable as a unilateral autonomous aldosterone-producing lesion. Careful investigations, including bilateral adrenal vein sampling, should be performed for the diagnosis.

Unilateral adrenal hyperplasia causing primary aldosteronism: limitations of I-131 norcholesterol scanning

Primary aldosteronism is a disorder that is commonly considered in patients referred to the hypertension clinic. The ease of measuring the random aldosterone-to-renin ratio in conjunction with an elevated serum aldosterone level has led to an increased screening for this disorder. Typically, patients undergo a confirmatory test after a positive screening test. However, once primary aldosteronism is confirmed, subtype delineation is critical to decide on the optimal treatment. We report a patient with resistant hypertension and primary aldosteronism with a normal computed tomographic scan of the adrenal glands, a left-sided uptake on adrenal scintigraphy, and a right-sided lateralization of aldosterone after adrenal vein sampling. A repeat adrenal vein sampling confirmed the aldosterone lateralization to the right adrenal gland, which was then removed laparoscopically. The patient had a good clinical and biochemical response, and unilateral adrenal hyperplasia was discovered at histology. Excessive reliance on adrenal scintigraphy without adrenal vein sampling may lead to serious errors in patient management.