Adrenal Mass and Hypokalaemia: The Zebra Among Horses

Pheochromocytoma rarely presents with unexplained hypokalaemia, although there are some case reports in the literature. The mechanism behind this could be the increased cellular potassium uptake promoted by beta-2-adrenoreceptor hyperactivation and insulin resistance. We present the case of a 68-year-old hypertensive female patient with a unilateral adrenal mass discovered on angio-CT and typical signs of adrenergic hyperstimulation (hypertensive crisis, headache, and sweating) associated with multiple arrhythmic episodes but with normal plasma and urinary catecholamine levels. During the work-up for hormonal hypersecretion and the cessation of anti-aldosterone medication, the patient presented resistant hypokalaemia. Due to uncorrectable hypokalaemia, we were unable to perform hormonal investigations for primary hyperaldosteronism and referred the patient for laparoscopic adrenalectomy. The histological diagnosis revealed left pheochromocytoma. Postoperatively, the patient experienced rebound hyperkalaemia. In a patient with a unilateral adrenal mass and hypokalaemia, besides primary hyperaldosteronism and adrenocorticotropic hormone-independent hypercortisolism, a possible pheochromocytoma should be ruled out as well by the clinician before surgery.