Four Cases of Hypovolemic Renin-Aldosterone Axis Deficiency Without Hyperkalemia Following Unilateral Adrenalectomy for Primary Aldosteronism

Abstract

ABSTRACT: Objective: Hyperkalemia can occur following unilateral adrenalectomy for primary aldosteronism due to hypoaldosteronism. We hereby report the cases of 4 male patients exhibiting prolonged failure of the renin-aldosterone (RA) axis in association with normal-to-high kalemia or labile blood pressure and, most significantly, a decrease in extracellular fluid volume (ECFV).Methods: Prior to surgery, all patients exhibited hypokalemic hypertension, with documented primary aldosteronism. Within a few weeks of undergoing unilateral adrenalectomy, the patients developed either mild hyperkalemia or labile blood pressure. Complementary investigations revealed a decrease in measured ECFV with inappropriate normal renal sodium excretion, low supine plasma renin activity, and insufficient orthostatic-related aldosterone production. The adrenocorticotropic hormone (ACTH) stimulation test demonstrated no glucocorticoid deficiency, along with responsive aldosterone secretion.Results: The discrepancy between the aldosterone response in the orthostatic position versus the ACTH stimulation test suggested that the aldosterone deficiency was largely due to RA axis depression. Recovery was confirmed between 3 and 18 months in all but one patient, the latter still requiring mineralocorticoid substitution 23 months later.Conclusion: Following unilateral adrenalectomy for primary aldosteronism, the occurrence of mild hyperkalemia prompted a functional evaluation of the RA system using an orthostatic stimulation test, rather than simply measuring baseline values and evaluating the glucocorticoid axis. In such cases, where RA depression is confirmed to cause latent hypovolemia, all treatments likely to further decrease plasma volume should be avoided, while mineralocorticoid substitution may be required.Abbreviations: ACTH = adrenocorticotropic hormone; AVS = adrenal vein sampling; BP = blood pressure; CT = computed tomography; ECFV = extracellular fluid volume; PA = primary aldosteronism; RA = renin-aldosterone