Dear Editor,

Segawa H et al. claim that the urinary sodium/potassium ratio can be used to screen for hyperaldosteronism; this finding appeared in your journal (Hypertension Research volume 44, pages1129–1137 (2021)). According to Table 3, the sensitivity for hyperaldosteronism by Na/K < 1.0 was ~45%, and the specificity was ~98%. When the cutoff point was increased to 3.0, the sensitivity was ~91%, and the specificity was ~40%. Therefore, the positive and negative likelihood for Na/K < 1.0 and <3.0 are 22.5 and 0.56 for <1.0 and 6.9 and 0.225 for <3.0. The prevalence of hyperaldosteronism is ~20% of hypertension, which suggests that most of the patients have normo- or low aldosteronism and that the Na/K ratio is above the cutoff point. When we screened hyperaldosteronism by Na/K < 1.0, 80% of the cases were Na/K > 1.0 (negative result), and the possibility of hyperaldosteronism was decreased by 0.56-fold. In contrast, when we set the cutoff point to Na/K < 3.0, the possibility of hyperaldosteronism decreased by 0.225-fold. In general, when screening for this disease, we should choose a lower negative likelihood test to avoid missing the disease. The Na/K ratio is ~4.6 from the INTERSALT study in East Asians [1] or lower (2.0) from NIPPON DATA80 [2]. These observations suggest that an appropriate Na/K cutoff for screening hyperaldosteronism is 3.0 which is not ‘low’ but instead is average for the Japanese population.