Does intravenous saline infusion differentiate primary aldosteronism from essential hypertension by suppressing plasma aldosterone concentration?
The saline infusion recumbency test is a rapid and simple method to evaluate plasma aldosterone suppression and identify primary aldosteronism.
Nine normal subjects and 18 patients with essential hypertension had similar suppression of plasma aldosterone concentration to 5 ng/100 ml or less after intravenous infusion of 2 liters of isotonic saline during four hours of recumbency. Six patients with aldosteronism and adrenal adenomas or glucocorticoid suppressible hyperplasia failed to suppress normally. One hypertensive hypokalemic patient with low plasma renin activity had elevated plasma deoxycorticosterone and failed to suppress his plasma aldosterone concentration below 5 ng/100 ml. Three of four patients with renovascular stenosis and hypertension suppressed normally. The fourth patient with a postinfusion plasma aldosterone concentration of 7 ng/100 ml was found to suppress normally when this value was expressed as percent of the two-hour upright value. This saline infusion, recumbency test is rapid and requires minimal patient preparation.
David C. Kem (Wed,) studied this question.