Differential Response to Thiazides and Spironolactone in Primary Aldosteronism

IN THE great majority of the reported cases of primary aldosteronism, the diagnosis has been suggested by finding abnormal serum electrolytes in a hypertensive patient. Recently, Conn and his associates have shown that some cases of primary aldosteronism do not evidence the classic abnormality of serum electrolytes.1 At this time, patients with primary aldosteronism with normal electrolytes may be suspected by the demonstration of suppressed plasma rennin activity in conjunction with increased aldosterone production.2The determination of plasma rennin activity is a highly specialized laboratory technique as is the determination of the aldosterone production rate. Both of these techniques can be performed in a very limited number of research laboratories at this time. The determination of urinary aldosterone in itself is a rather specialized laboratory procedure. Elevated levels are not specific for primary aldosteronism and some cases of primary aldosteronism have had normal urinary aldosterone levels.3,4 We will present studies