Effect of Hypokalemia on Screening for Primary Aldosteronism

Context Primary aldosteronism (PA) is a common, underdiagnosed, and treatable cause of hypertension. Guidelines recommend testing for hypokalemia, but current practices and their impact are unknown. Objective To estimate the impact of hypokalemia on the results of PA screening in clinical practice. Methods We studied electronic health records for adults who received longitudinal care within a large, integrated health system between 2007 and 2017 and underwent paired blood aldosterone and renin testing. Patients were grouped based on concurrent blood potassium concentrations. Results We found that 2,940 (82%) of the 3,571 patients screened for PA had concurrent potassium testing. Among all patients with a negative PA screen, 18% of patients did not have concurrent potassium testing and 14% of those tested were hypokalemic. Of the screen-negative hypokalemic patients, 77% were not retested. Among patients with repeated screens, we found that initial potassium concentration was a predictor of PA screen positivity on repeat. A one standard deviation lower initial potassium concentration was associated with a 74% higher odds of screen positivity on repeat, independent of initial aldosterone and renin results. Conclusions In-practice clinical data demonstrate that unrecognized and uncorrected hypokalemia contributes to the underdiagnosis of PA. Universal potassium testing and rescreening for PA in the setting of hypokalemia would likely substantially improve the identification and thereby management of PA.