To the Editor: Angiotensin-converting–enzyme (ACE) inhibitors have been shown to reduce proteinuria and slow the progression of renal disease.¹ Although to date angiotensin II has been the focus of attention as the primary mediator of the renin–angiotensin–aldosterone system, several studies have raised the possibility that aldosterone itself has a role in mediating progressive renal disease.²,³ Pitt et al.⁴ showed that blockade of aldosterone receptors by spironolactone significantly reduced the risk of morbidity and death among patients with heart failure who were already receiving ACE inhibitors. The authors hypothesized that the benefits were not due to the hemodynamic effects of . . .