643 COSYNTROPIN STIMULATION TEST IS USEFUL IN DISTINGUISHING UNILATERAL FROM BILATERAL PRIMARY ALDOSTERONISM

Abstract

Background: Primary aldosteronism (PA) is a common cause of endocrine hypertension. Although adrenal venous sampling (AVS) is the gold standard for subtype classification, it is available in limited specialized centers. The aim of the study was to investigate the clinical significance of cosyntropin (ACTH) stimulation test for subtype classification in PA. Design and Methods: Sixty patients with PA who underwent ACTH stimulation test were studied. The subjects were diagnosed as having either unilateral (n = 41) or bilateral PA (n = 19) based upon AVS, adrenal scintigraphy, and/or adrenal surgery. We evaluated the diagnostic significance of ACTH stimulation test in differentiating unilateral PA from bilateral PA. Results: Peak PAC (P < 0.01) and peak PAC/cortisol (P < 0.05) after ACTH stimulation were significantly higher in patients with unilateral PA than those with bilateral PA. Peak PAC-basal PAC (ΔPAC) was higher in patients with unilateral PA than those with bilateral PA, although the difference was not statistically significant. Receiver operating characteristic curve analysis for the diagnosis of unilateral PA showed a peak PAC value of 403 pg/ml had a sensitivity of 70.7% and specificity of 79.0%, and a value of 596 pg/ml had a sensitivity of 46.3% and specificity of 100%. A peak PAC/cortisol value of 19.7 (cortisol, mcg/dl) had a sensitivity of 58.5% and specificity of 89.5%, and a value of 30.5 had a sensitivity of 26.8% and specificity of 100%. Conclusions: ACTH stimulation test could discriminate between unilateral and bilateral PA and is useful in selecting the patients who should undergo AVS before surgery.