Role of imaging and adrenal venous sampling techniques in the diagnosis of primary aldosteronism

Abstract

Background: Primary aldosteronism (PA) is a rare condition characterized by inappropriately high secretion of aldosterone, independently of the renin-angiotensin system, not suppressed by sodium loading test. PA represents the most common cause of secondary hypertension and its early detection and treatment can help reduce the cardiovascular (CV) risk. Case presentation: We report on a 42-year-old man who was referred to an outpatients’ clinic reporting headache and vomiting associated with hypertension and was discharged with oral antihypertensive medication (irbesartan) and low-sodium diet. Three years later, he underwent further hospitalization for muscle pain in lower limb associated with severe hypokalemia (1.7 mmol/L) and elevated creatine phosphokinase (CPK) levels (2634 U/L). Abdominal CT scan excluded the presence of adrenal lesions. Acute intravenous potassium chloride (KCL) supplementation normalized serum potassium level and the patient was discharged with diagnosis of rhabdomyolysis and hypokalemia and with antihypertensive medication (spironalactone: 100 mg/day and amlodipine: 5 mg/day) and oral KCL supplementation (600 mg/day). After pharmacological washout, an inappropriately high aldosterone concentration (75.10 pg/ml) and very low renin level (1.10 pg/ml) were detected. PA diagnosis was confirmed by oral saline infusion test (SIT). Aldosterone levels did not normalize after dexamethasone suppression testing. Abdominal MRI showed a nodule measuring 6 mm in the right adrenal. A subsequent adrenal venous sampling (AVS) confirmed the unilateral (right) lateralization of the aldosterone hypersecretion. Conclusion: Although invasive, AVS is the gold standard test to differentiate PA subtypes in patients who can be considered ideal candidates for unilateral adrenalectomy.