Endocrine Abstracts

Introduction: Hyperkalemia due to zona glomerulosa (ZG) insufficiency is generally transient and mild for patients with aldosterone-producing adenoma (APA) after adrenalectomy. We report here a case with prolonged ZG insuffiency requiring long-term mineralocorticoid replacement (MR) therapy.

Case report: A 45-years-old female with hypertension and hypokalemia admitted to outpatient clinic with incidentally detected right adrenal adenoma (3 cm) showing signal loss on opposed-phase images of MRI. Laboratory tests revealed high plasma aldosterone concentration (PAC) (72 ng/dl, N: 7–30 ng/dl), supressed plasma direct renin concentrations (DRC) (5.25 ng/l, N: 5.41–34.53 ng/l) and high PAC/DRC ratio (13.71). PAC after saline infusion test was 30.7 ng/dl. After confirmation with adrenal venous sampling (AVS), right adrenalectomy was performed laporoscopically. Serum urea, creatinine, sodium, PAC (19.6 ng/dl) and DRC (13.6 ng/l) were in normal limits on postoperative 20th day; but serum potassium was markedly increased (5.9 mmol/l). The causes of pseudohyperkalemia and hyperkalemia were excluded. Because of low suppression index in the contralateral adrenal during AVS, hypoaldosteronism was thought to be the etiology as PAC did not increase while serum potassium level was higher than 5 mmol/l. Patient was followed-up with high-sodium, low-potassium diet on polystyrene sulfonate therapy. On the second month postoperatively, serum potassium was still high (5.6 mmol/l). MR therapy with fludrocortisone 0.1 mg/day was started for persistent hyperkalemia. Treatment continued for eight months until PAC and DRC raised up to 23.27 and 20.8 ng/l, respectively. After then, serum potassium concentration remained at the upper limit of normal range (5 mmol/l) with normal renal function tests, PAC (10.8 ng/dl) and DRC (8.1 ng/l) without replacement.

Conclusion: Suppression of contralateral ZG function by supressed plasma renin level in APA can lead to ZG insufficiency and hypoaldosteronism after adrenalectomy. Hypoaldosteronism cause impairment of renal potassium clearance and hyperkalemia. MR therapy may be essential in case of prolonged hyperkalemia.