Prolonged zona glomerulosa insufficiency causing hyperkalemia in primary aldosteronism after adrenalectomy.

CONTEXT: Unilateral adrenalectomy is the therapy of choice in aldosterone-producing adenoma (APA). Zona glomerulosa (ZG) insufficiency causing hyperkalemia after adrenalectomy has been described in case reports.

OBJECTIVE: Our aim was to analyze the clinical relevance of ZG insufficiency causing hyperkalemia after adrenalectomy in a large series of patients with APA.

DESIGN: This was a retrospective chart review.

SETTING: The study was conducted at two tertiary university referral centers in Germany.

PATIENTS: Data from 110 patients with confirmed APA adrenalectomized at the centers in Munich and Berlin between 2004 and 2012 were analyzed.

MAIN OUTCOME MEASURES: The primary outcome was the incidence of ZG insufficiency causing hyperkalemia after adrenalectomy; the secondary outcome was the identification of risk factors predisposing for hyperkalemia.

RESULTS: Eighteen of 110 patients (16%) developed postoperative hyperkalemia. The majority of these patients (n = 14) had undetectable plasma aldosterone levels after adrenalectomy; four had low aldosterone levels. In 12 of these patients, hyperkalemia was documented only once and resumed spontaneously. Prolonged hypoaldosteronism accompanied by hyperkalemia was observed in six patients (5% of total cohort). These patients needed continuous mineralocorticoid replacement therapy for 11-46 months. Mineralocorticoid antagonist treatment for 4 wk prior to surgery did not prevent hyperkalemia. In multivariate analysis, preoperatively decreased glomerular filtration rate and increased serum creatinine as well as increased postoperative creatinine and microalbuminuria remained significant predictors of hyperkalemia.

CONCLUSION: Persistent postoperative hypoaldosteronism with hyperkalemia occurs in 5% of adrenalectomized PA patients through prolonged ZG insufficiency, requiring long-term fludrocortisone treatment. Potassium levels after adrenalectomy must be monitored to avoid life-threatening hyperkalemia.