Persistent Hyperkalemia Post-Adrenalectomy for Aldosterone-Producing Adenoma

Abstract

Background:Post-operative hypoaldosteronism due to chronic suppression of the renin-aldosterone axis of the contralateral gland can be complicated with hyperkalemia. We describe a case of persistent hyperkalemia post adrenalectomy for aldosterone-producing adenoma. Clinical Case: A 47-year-old male was first diagnosed with hypertension in 2011. He was investigated for secondary hypertension after hospital admission in 2019 for hypertensive urgency and symptomatic hypokalemia (potassium, K 1.9–2.3 mmol/L, n = 3.5–5.0). Subsequent laboratory investigation revealed elevated serum aldosterone (3565 pmol/L, n < 103) with an aldosterone renin ratio of 115 (n < 35). A confirmatory test with saline loading showed an unsuppressed serum aldosterone level of 1840 pmol/L. Adrenal CT reported a 4.1-cm, heterogeneous left adrenal lesion. A diagnosis of primary aldosteronism was made, and he underwent laparoscopic left adrenalectomy in July 2020. Histopathology examination was consistent with adrenal cortical adenoma. Both potassium supplementation and spironolactone were stopped immediately postoperatively. Two weeks later, he developed symptomatic hyperkalemia (K 6.0 mmol/L), requiring hospital admission, and started on potassium binder. Throughout clinic follow-ups, potassium remained high (K 5.4–6.1 mmol/L), despite low potassium diet and potassium binder. His case was co-managed with the nephrology team and given a trial of frusemide and sodium bicarbonate to normalize his potassium. However, after 4 months, he remained hyperkalemic. Repeated serum aldosterone was not elevated (<103 pmol/L). He was then started on fludrocortisone and finally managed to achieve serum potassium normalisation (K 4.1–4.5 mmol/L). Conclusion: This case highlights the importance of monitoring potassium levels in all patients after adrenalectomy, particularly those with clinical risk factors. Retrospective studies by Park et al and Fischer et al reported that a long duration of hypertension, impaired preoperative renal function, older age, and large adenoma size represent risks for developing hyperkalemia postoperatively, whereas the use of mineralocorticoid receptor antagonists preoperatively does not prevent hyperkalemia. Treatment includes a low potassium diet, a high sodium diet, adequate hydration, potassium binder, frusemide, and fludrocortisone. In some cases, hyperkalemia may be prolonged, necessitating long-term fludrocortisone therapy, up to 11–46 months². References: 1. Park KS, Kim JH, Ku EJ, et al. Clinical risk factors of postoperative hyperkalemia after adrenalectomy in patients with aldosterone-producing adenoma. Eur J Endocrinol. 2015 Jun;172(6):725–31. 2. Fischer E, Hanslik G, Pallauf A, et al. Prolonged zona glomerulosa insufficiency causing hyperkalemia in primary aldosteronism after adrenalectomy. J Clin Endocrinol Metab. 2012 Nov;97(11):3965–73.