The objective of this study was to highlight the importance of hypokalemia correction in the diagnosis of primary aldosteronism (PA), which is not emphasized sufficiently in the literature or clinical guidelines. We report the cases of 4 patients with hypokalemia and hypertension in whom the screening and confirmatory diagnosis of PA was made possible only after potassium level normalization. Cases 1 and 2 were referred for evaluation of hypokalemia and hypertension while cases 3 and 4 were admitted to the hospital for severe generalized weakness and palpitations, respectively. Initial labs for all were remarkable for hypokalemia, with potassium levels of 1.9 to 3.2 mEq/L (normal range: 3.5 to 5.0 mEq/L), relatively low aldosterone of <1.0 to 13.0 ng/dL, and elevated aldosterone-to-renin ratio. Saline infusion tests were performed for cases 1 and 2 when potassium was 3.2 mEq/L with post-test aldosterone levels of 9.0 and 3.0 ng/dL, respectively, suggesting the diagnosis of PA as less likely. After potassium repletion, with potassium levels of 3.7 to 4.8 mEq/L, screening aldosterone levels were 27.0 to 64.0 ng/dL, the aldosterone-to-renin ratios were 34.5 to 128.0, and post-saline infusion test aldosterone levels were 27.0 to 64.0 ng/dL, confirming the diagnosis of PA. Computed tomography scans revealed unilateral adrenal adenomas, adrenal vein sampling confirmed the localization, and successful adrenalectomy was done for all 4 cases. Hypertension and hypokalemia resolved in the first 3 cases and improved in the fourth. Hypokalemia may confound the screening and confirmatory work up of PA due to false-negative results. Potassium normalization is very important for correct diagnosis of PA.
