Outpatient screening tests for primary aldosteronism.

The assessment of basal plasma aldosterone and renin concentrations, and urinary aldosterone excretion has been compared with their values after a suppressive test employing mineralocorticoid induced volume expansion in five patients with primary aldosteronism and in patients with essential hypertension. Reliance upon measurements of basal plasma aldosterone concentration, plasma renin/aldosterone ratio and urine aldosterone excretion alone proved unsatisfactory for distinguishing patients with primary aldosteronism. However these patients, in contrast to those with essential hypertension, showed elevated values or no decrease in plasma aldosterone concentration following three days treatment with 400 mug fludrocortisone (florinef) daily. It is proposed that the assessment of basal plasma renin activity together with florinef suppression of plasma aldosterone are the most effective and convenient outpatient screening procedures in the diagnosis of primary aldosteronism.