Unilateral adrenal hyperplasia: a novel cause of surgically correctable primary hyperaldosteronism.

BACKGROUND: Primary hyperaldosteronism may be caused by an aldosterone-producing adenoma (APA), which is correctable by unilateral adrenalectomy or by idiopathic adrenal hyperplasia, a bilateral disease without any indication for surgery. This study sought to assess the prevalence and the results of surgery in unilateral adrenal hyperplasia (UAH).
METHODS: The study included 35 patients who underwent unilateral adrenalectomy because of primary hyperaldosteronism after unequivocal successful lateralization by adrenal venous sampling. Demographics, biochemical evaluation, and blood pressure were assessed pre- and postoperatively. Pathology was categorized as APA (isolated adenoma), nodular (multiple micromacronodules), and diffuse UAH (gland thickening without nodules).
RESULTS: Pathology revealed 9 APAs and 23 nodular and 3 diffuse UAHs. Patients with APAs and UAHs were statistically similar regarding demographics and preoperative blood pressure levels. Bilateral adrenal involvement was evident at imaging in 10 patients (11% in APA versus 35% in UAH, P = NS). After surgery, biochemical cure of the disease was achieved in all patients; blood pressure levels normalized in 66.6% of patients and ameliorated in 22.2% in APA versus 34.6% and 50% in patients with UAH (P = NS). At a long-term follow-up, only 1 patient with nodular UAH experienced a biochemical recurrence of disease.
CONCLUSION: UAH is not rare, sharing the same features of APA. When disease lateralization is confirmed by adrenal venous sampling, unilateral adrenalectomy achieves excellent long-term results.