Value of plasma renin activity changes with different posture on identification of primary aldosteronism

Abstract

Objective To evaluate the diagnostic ability of primary aldosteronism(PA) via the changes of plasma renin activity(PRA) with postural variation in hypertensive patients. Methods Three hundred and seven patients had received the estimation of PRA, aldosterone level on basal sitting posture and after 2 hours on upright, sitting and supine posture, and collection of other biochemistry measurements.PA group was defined according to aldosterone/renin acrivity ≥554 pmol/L·[μg/ (L·h)]-1 and plasma aldosterone concentration≥277 pmol/L after saline infusion test, the rest were regarded as no-PA group.Related parameters were calculated to show the sensitivity and specificity, and so on. Results In PA group, the levels of PRA upright, sitting, supine [0.61 μg/(L·h), 0.62 μg/(L·h), 0.31 μg/(L·h)] were lower than those of no-PA group[1.42 μg/(L·h), 1.18 μg/(L·h), 0.51 μg/(L·h)], and the differences were statistically significant (F=11.465, 12.052, 10.296; P=0.001). The D-value[0.24 μg/(L·h)] of PRA between PRA upright and PRA supine in PA group was lower than that [0.78 μg/(L·h)] in no-PA group, and the difference was statistically significant (F=8.303, P=0.004). The sensitivity values of PRA upright <1.0 μg/(L·h) or PRA upright-PRA supine<0.6 μg/(L·h) to diagnose PA were 64% and 70%, respectively; the specificity values were 62% and 68%; the negative predictive values were 91% and 93%, respectively.Using PRA upright<1.0 μg/(L·h) and PRA upright-PRA supine <0.6 μg/(L·h) as diagnostic criterion of PA, the sensitivity and specificity values were 45% and 88%, respectively. Conclusions There is a low efficacy to use the changes of PRA via posture alteration as a diagnostic standard, but it′s brief and safe to provide some referenced information to doctors on the identification of PA. Key words: Hypertension; Renin; Aldosterone