Endocrine Abstracts

Background: Post-adrenalectomy persistent hyperkalemia, that lasts >3 months and needs to be treated, is a potentially serious, but not apprehensively investigated complication after surgical treatment in patients with aldosterone-producing adenomas (APA).

Case report: A 53-year-old male presented type 2 diabetes mellitus and a 10-year history of resistant hypertension requiring multidrug treatment with antihypertensives of eight different classes. Primary aldosteronism with non-suppressive serum aldosterone (0.43\.0.32 nmol/l, normal value <0.28 nmol/l) was confirmed in a standard saline infusion test. MRI scan revealed a left-sided adrenal mass (21×30 mm). Adrenal vein sampling confirmed left-sided unilateral hypersecretion of aldosterone. Patient underwent an uneventful left adrenalectomy, following which decrease of blood pressure was observed. Two months after surgery patient presented with hyperkalemia (6.25 mmol/l, normal value 3.6–5.3 mmol/l). His aldosterone (0.03 nmol/l, normal value 0.08–1.11 nmol/l) and renin levels (4.1 mIU/l, normal value 4.4–46.1 mIU/l) were inappropriately low, suggesting hyporeninemic hypoaldosteronism.

Discussion: Post-operative hypoaldosteronism is well documented in unilateral adrenalectomy for APA. It is related to a decrease in adrenal mass, or a transient supression of the contralateral gland via suppressed plasma renin levels, impairing renal K⁺ clearance and consequent hyperkalemia. In most cases, hyperkalemia is only transient, occurs only once during the first months after adrenalectomy and resumes spontaneously without intervention. Male sex, older age, longer duration of hypertension, lower nadir serum K⁺ and already preoperative impaired renal function are identified as the most important factors of post-adrenalectomy hyperkalemia.

Conclusion: When persistent hyperkalemia is detected, mineralocorticoid replacement treatment, with a low-potassium and high-sodium diet should be initiated. Drugs that may have prevented adequate recovery of renin–aldosterone axis should be stopped. Endocrinologists should be aware of this complication and should closely monitor K⁺ levels and renal function after adrenalectomy indicated for APA.