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Postural Stimulation tests (PST) from 146 patients with primary aldosteronism were reviewed: 83 had an aldosterone-producing adenoma (APA), 48 idiopathic hyperaldosteronism (IHA), nine primary adrenal hyperplasia (PAH), and six aldosterone-producing renin-responsive adenoma (AP-RA). Plasma aldosterone and Cortisol levels were measured after overnight recumbency and in response to upright posture for 2 to 4 h. The test was considered invalid in 32% of the patients because Cortisol levels increased during the maneuver. As both Cortisol and aldosterone are responsive to ACTH in subjects with primary aldosteronism, as well as in normal subjects, we examined their percent variation instead of the absolute values. In order to validate those tests in which Cortisol increased, we subtracted the percent Cortisol change from the percent aldosterone response. An aldosterone increase of less than 30% (considered a positive response for the presence of an adenoma) identified 76 of the 89 patients with an adenoma (APA and AP-RA) (sensitivity of 85%). Among the 13 false-negative tests, six were proven cases of AP-RA. In each and every case an adenoma was detected by CT/MRI scanning (or bilateral adrenal vein catheterization). Hypertension was ameliroated or cured by surgery. A postural response of less than 30% was also present in 11 of the 57 patients who did not have a discrete adenoma confirmed by imaging techniques (specificity of 81%). Among these false-positive results there were the nine cases of PAH where the hypertension could be ameliorated or cured by partial removal of hyperplastic adrenal tissue. The positive predictive value of the PST is 87%, but if all potentially curable cases are included, regardless of the imaging results (APA plus PAH), it would be as high as 98%. Thus, the PST associated with an abdominal CT/MRI scanning provides a reliable method for the identification of all surgically correctable subsets of primary aldosteronism. Am J Hypertens 1991;4:786–791
Fontes et al. (1991) studied this question.