Simple standing test without furosemide is useful in the diagnosis of primary aldosteronism

Primary aldosteronism (PA) is a well-known cause of secondary hypertension. We have long performed the simple standing test in patients with PA. On the other hand, there are few reports on the usefulness of the simple standing test in PA. This study is a single-center, retrospective, observational study. A total of 173 patients with hypertension or adrenal tumor admitted to Kawasaki Medical School were included. Eighty patients who met the exclusion criteria were excluded, and 31 patients without PA (non-PA), 26 patients with unilateral PA, and 36 patients with bilateral PA were included in the study. The simple standing test was performed after 120 min of standing or sitting followed, and the aldosterone/renin ratio (ARR) and percentage of increase plasma aldosterone concentration (%increase of PAC) was calculated. The mean ARR in the simple standing test in unilateral PA (1143 (528-2200)) and bilateral PA subjects (521 (374-765)) were significantly higher compared to non-PA subjects (152 (102-240)) (p < 0.0001, p = 0.0013, respectively). The percentage increase of PAC after standing loading was significantly lower in unilateral PA subjects (110 (96-140)) compared to non-PA subjects (187 (155-244)) (p = 0.0003), with no difference between non-PA and bilateral PA subjects (p = 0.99). The cutoff value of the ARR in the simple standing test for diagnosis of PA in this study was 364 (AUC = 0.948, sensitivity = 83.8%, specificity = 93.5%, false positive rate = 3.7%, false negative rate = 25.6%, p < 0.001), which was not inferior to the diagnostic performance of the captopril loading test. The diagnostic performance of the simple standing test for PA was not inferior to that of the captopril loading test. The percentage increase of PAC in unilateral PA subjects was significantly lower compared to bilateral PA subjects. These results demonstrate the usefulness of the simple standing test, which can be performed simultaneously with general screening tests of PA.