Endocrine Abstracts

Context: Unilateral adrenalectomy is the therapy of first choice in aldosterone producing adenoma (APA). Improvement of blood pressure (BP) and hypokalemia is achieved in the majority of patients. Because of hypoaldosteronism, hyperkalemia can develop in the postoperative course. Our aim was to analyze the frequency of hyperkalemia, to determine the cause of hypoaldosteronism and to assess the influence of preoperative mineralocorticoid antagonist (MRA) therapy at our center.

Patients: We analyzed retrospectively data from 69 patients with APA after adrenalectomy. Hyperkalemia was defined as potassium >5.0 mmol/L. Patients were seen at the out-patient clinic. BP, aldosterone, renin, serum potassium, creatinine, microalbuminuria and the number of antihypertensive medications were recorded. Dosage and duration of preoperative treatment with MRA were assessed.

Results: We observed postoperative hyperkalemia in 16 patients (23.2%). In 12 of these patients, hyperkalemia was mild without need for further treatment. In 4 patients, the hyperkalemia persisted for 15, 13, 11 and 10 months. The maximum serum potassium observed was 7.1 mmol/L. These patients needed dietary advice, treatment with fludrocortisone (0.1–0.3 μg/day), forced diuresis and bicarbonate administration. They suffered from secondary hypoaldosteronism as plasma renin concentrations remained postoperatively suppressed. In univariate analysis, postoperative hyperkalemia was significantly associated with higher age at diagnosis (57.5+3.2 vs. 49.7+1.5 years, P=0.021) and with a worse renal function postoperatively (creatinine 1.29+0.11 vs. 0.98+0.04 mg/dl, P=0.025). Although 49 patients received spironolactone in a dose of 51.6+3.0 mg (treatment time 2.3+0.3 months) and 5 patients eplerenone in a dose of 30.0+5 mg (5.0+3.3 months) prior surgery, this did not have a significant impact on postoperative hyperkalemia.

Conclusion: Clinically meaningful postoperative hyperkalemia occurs in 5.8% of adrenalectomized PA patients, caused by prolonged secondary zona glomerulosa insufficiency. Potassium levels after adrenalectomy must be monitored to avoid life-threatening hyperkalemia. Pre-treatment with MRA does not appear to be effective in preventing hyperkalemia.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.