Primary aldosteronism was first described by Jerome Conn in 1955 in a patient with an aldosterone-producing adrenal adenoma. It’s now a widely recognized cause of secondary hypertension. The following case illustrates the challenges of making clinical diagnosis of aldosterone producing adrenal adenoma.

A middle-aged woman with medullary sponge kidney and nephrocalcinosis was first diagnosed with adrenal mass on a computed tomography scan performed for kidney stone evaluation about 10 years previously. She had normal serum potassium and serum bicarbonate levels.

Subsequently, she was found to have elevated blood pressure and was referred to the Department of Nephrology and Hypertension for further evaluation. Her serum aldosterone level was 475.5 ng/dL. Despite achieving 290 mmol/day of urinary sodium, she had no kaliuresis following an oral salt loading test.

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The urinary aldosterone level was 231 µg/day. After further discussion with colleagues in the Department of Urology, the patient successfully underwent robotic-assisted laparascopic adrenalectomy. She became normotensive requiring no further antihypertensive medication.

Aldosterone is a potent mineralocorticoid secreted by the zona glomerulosa of the adrenal cortex. Unlike cortisol, which is inactivated to cortisone by 11-β hydroxysteroid dehydrogenase, aldosterone avidly binds to the mineralocorticoid receptor in the distal nephrone leading to sodium retention resulting in anti-natriuresis, volume expansion, hypertension, metabolic alkalosis and renal potassium wasting.

The patient had a very high levels of circulating serum aldosterone ( 475.5 ng/dL) but did not present with hypokalemia or metabolic alkalosis, and did not have resistant hypertension which delayed the diagnosis of aldosterone producing adenoma. We thought that the renal tubular disease resulting from nephrocalcinosis caused the distal tubule to be resistant to the action of aldosterone even in the presence of high distal sodium delivery and high aldosterone levels.

This case illustrates the challenges of making a clinical diagnosis of primary aldosteronism in the presence of renal tubular disease.