Renal cysts and hypokalemia in primary aldosteronism: results of long-term follow-up after treatment.

BACKGROUND: Cross-sectional studies have reported an elevated prevalence of renal cysts in patients with primary aldosteronism. The nature of this association could be related to hypokalemia and/or hypertension and has never been evaluated in prospective studies. METHODS: A consecutive sample of 54 patients with tumoral or idiopathic primary aldosteronism was followed after adrenalectomy or treatment with aldosterone antagonists. At baseline, renal cysts were evaluated by renal ultrasound and patients with primary aldosteronism were compared with 323 essential hypertension patients with the same severity and duration of disease, and 113 age- and sex-matched normotensive subjects. RESULTS: The adjusted prevalence and average number of renal cysts were significantly greater in patients with primary aldosteronism than in patients with essential hypertension and normotensive subjects. Multivariate analysis revealed that age and plasma potassium levels were independently associated with the presence of renal cysts in patients with primary aldosteronism. Treatment of primary aldosteronism decreased blood pressure (BP) and restored normal potassium concentrations. After a median follow-up of 6.2 years, no significant change from baseline of cyst number and cyst total volume was observed in patients with both tumoral and idiopathic aldosteronism and in a subset of 100 patients with essential hypertension. In patients with primary aldosteronism, stepwise logistic analysis showed that the presence of renal cysts was associated with worse BP outcome after treatment. CONCLUSION: Renal cystic disease is highly frequent in patients with primary aldosteronism and either surgical or medical treatment halt its progression, supporting the contention that hypokalemia and its severity are the main contributors to cyst formation in these patients.