1. Prolonged treatment with spironolactone in low-renin hyperaldosteronism invariably corrects plasma electrolyte abnormalities and usually lowers blood pressure.
2. Total exchangeable sodium, total body water, extracellular fluid and plasma volumes are reduced; total exchangeable and total body potassium, plasma renin and angiotensin II concentrations are increased.
3. Spironolactone is similarly effective in patients with apparently isolated deoxycorticosterone (DOC) excess; also in suspected mineralocorticoid excess not associated with elevation of aldosterone or DOC.
4. Studies of amiloride reveal similar effectiveness to spironolactone in low-renin hyperaldosteronism and in suspected mineralocorticoid excess.