No abstract

Primary hyperaldosteronism (PA) is one of most common causes of surgically remediable hypertension. The incidence of PA is much higher (5-10%) compared to what was previously (<1%) reported. 1 Patients with PA are at a greater risk for development of cardiovascular morbidity and mortality, renal and metabolic complications when compared to other hypertensive patients. 2 The most common causes of PA are aldosterone producing adenomas (APA), unilateral and bilateral diffuse hyperplasiad (DH). Sixty percent of patients with aldosterone over production have bilateral disease, and mineralcorticoid antagonists are the treatment of choice whereas, 40% have unilateral disease and may be cured by unilateral laparoscopic adrenalectomy (LA). Unilateral adrenal hyperplasia (UAH) is a rare entity. Recently a Swedish study showed that 50 patients were detected to have UAH postoperatively. 3 The long term follow-up data on postoperative adrenalectomy for cases of UAH is limited. A retrospective study from China reported unilateral LA in 164 patients. Following surgery, blood pressure normalised in 54%, improved in 44% and hypokalemia resolved in all patients. 4 Preoperative work-up is critical for distinguishing unilateral from bilateral disease. Aldosterone-renin ratio (ARR) is the most sensitive screening test for PA but the levels may be altered depending on the testing conditions, medications, variable assay methods and different cut-off levels for diagnosis. An elevated ARR >30 along with PAC >20 ng/dL is now universally accepted as a further confirmatory test in patients with PA. Hypokalemia as a screening test has low sensitivity and even the presence of hypokalemia has low negative predictive value. The commonly used confirmatory tests are saline infusion test (SIT), oral sodium loading test, fludrocortisone suppression test, and Captopril challenge test. There is no single gold standard confirmatory test for PA, thus patients usually required more than one test to establish the diagnosis. Confirmatory tests that are also helpful in ruling out false ARR positive cases and thereby one can avoid invasive procedures like adrenal venous sampling (AVS). There is no single gold standard confirmatory test for PA as reliability, sensitivity and specificity varies, as shown by different studies. A prospective study from Italy showed that on the saline infusion test aldosterone with a cut-off of >6.8ng/dL has moderate sensitivity and specificity in discrimating between APA and idiopathic bilateral hyperplasia (IHA). 5 An adrenal computed tomography (CT) is the initial test of choice for localizing and sub-typing of aldosterone producing tumors. The CT scan finding in PA can be classified into cross-sectional image positive lesions which include APA and aldosterone producing carcinoma. The image negative PA includes unilateral micro-APA (<1 cm), UAH, IHA, multiple adrenocortical micronodule (MN) and bilateral macro-or microadenomas (or a combination of the two). The APA is typically characterized by a <2 cm size unilateral hypoden...