Diagnostic Accuracy of Computed Tomography in Predicting Primary Aldosteronism Subtype According to Age (Endocrinol Metab 2021;36:401-12, Seung Hun Lee et al.).

We appreciate the insightful comments from Dr. Singhania regarding our recent publication. We reported that patients with hypokalemia, a plasma aldosterone concentration >30.0 ng/dL, and unilateral lesions on computed tomography were at high risk of unilateral primary aldosteronism regardless of age [1]. We would like to respond as follows.

First, Dr. Singhania pointed out that the importance of hypokalemia in diagnosing primary aldosteronism—particularly unilateral adenoma—was overemphasized. We agree that the prevalence of hypokalemia was relatively low in patients with primary aldosteronism. However, the presence of hypokalemia might reflect the disease severity, and a recent clinical guideline suggested that the presence of hypokalemia enables bypassing confirmatory testing for primary aldosteronism [2]. Our study found that hypokalemia alone was not a significant predictor, but that it became a more significant predictor together with other criteria. Moreover, previous studies have suggested that hypokalemia is a significant predictor of unilateral primary aldosteronism [3-5].

Second, Dr. Singhania pointed out that confirmatory testing can be skipped in the clinical setting of hypertension, spontaneous hypokalemia with a plasma aldosterone concentration >555 pmol/L (>20 ng/dL), and plasma renin activity <1 ng/mL/hr (or a plasma renin concentration below the lower limit of the reference range). We also agree that confirmatory testing is not necessary for patients with primary aldosteronism, according to the previously-mentioned guideline [2]. However, our study included patients from 2000 to 2018, which included the period before the guideline was published. Thus, our two centers consistently conducted confirmatory tests in patients with primary aldosteronism.

We deeply appreciate Dr. Singhania’s valuable comments, which enriched the understanding of our article.