Context: Experimental animal studies indicate that exposure to increased aldosterone levels might result in renal damage, but the clinical evidence supporting this role of aldosterone is preliminary.
Objective: To determine the long-term outcome of renal function in patients with primary aldosteronism after surgical or medical treatment.
Design, setting, and participants: Prospective study conducted at an Italian university medical center among a consecutive sample of 50 patients who were diagnosed as having primary aldosteronism between January 1994 and December 2001 and who were followed up for a mean of 6.4 years after treatment with adrenalectomy or spironolactone. Patients with primary aldosteronism were compared with 100 patients with essential hypertension, matched for severity and duration of hypertension. All patients were treated with antihypertensive drugs to reach a target blood pressure of less than 140/90 mm Hg.
Main outcome measures: Primary outcome measures were rates of change of glomerular filtration rate and albuminuria during follow-up. Detection of new-onset microalbuminuria and restoration of normal albumin excretion during follow-up were considered as secondary outcomes.
Results: At baseline, glomerular filtration rate and albuminuria were higher in patients with primary aldosteronism than those with essential hypertension. The mean blood pressure during the study was 136/81 mm Hg in the primary aldosteronism group and 137/81 mm Hg in the essential hypertension group. Glomerular filtration rate and albuminuria declined during the initial 6-month period in both groups, with a change that was significantly greater (P<.001 for both variables) in patients with primary aldosteronism. Subsequent rate of decline of glomerular filtration was comparable in the 2 groups, whereas albuminuria did not progress in the remainder of the follow-up. Restoration of normal albumin excretion from microalbuminuria was significantly more frequent in primary aldosteronism than in essential hypertension (P = .02).
Conclusion: In the majority of patients in this study, primary aldosteronism was characterized by partially reversible renal dysfunction in which elevated albuminuria is a marker of a dynamic rather than structural renal defect.