High prevalence of hypokalemia in acute psychiatric inpatients

Background: Hypokalemia is an easily identifiable, clinically important but commonly neglected condition in psychiatric patients. This study intended to examine the prevalence of hypokalemia and its clinical correlates in acute psychiatric inpatients. Method: This retrospective study was conducted over a 6 month period in 2008. The case notes, computerized records and laboratory results of all patients who were consecutively admitted to the acute psychiatric wards in a University-affiliated regional psychiatric unit were studied. Result: Three hundred forty-seven patients out of 440 admissions were studied. Hypokalemia, as defined by serum potassium level of less than 3.5 mmol/L, was found in 20.5% of patients with a higher prevalence in psychotic patients (27.7%). The mean potassium level of psychotic patients was lower than that of the overall study population (3.72 vs. 3.81 mmol/L, P<05). White cell counts among the hypokalemic patients were higher than those without hypokalemia (7.8 vs. 7.1 x 10(9)/L, P=.02). Conclusion: Hypokalemia was common among acute psychiatric inpatients. Both agitation and the use of antipsychotics were postulated to contribute to the high prevalence of hypokalemia among acutely ill psychiatric patients. (C) 2009 Elsevier Inc. All rights reserved.