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Hypokalemia in Acute Medical Patients: Risk Factors and Prognosis

      Abstract

      Objective

      Hypokalemia is one of the most common electrolyte disorders in hospitalized patients. It is associated with a high mortality rate among patients with cardiovascular disease. Whether hypokalemia confers a similar risk in an unselected hospitalized population is not well established.

      Methods

      We conducted a prospective cohort study involving all first-time admissions (n = 11,988) to the Acute Medical Department at Odense University Hospital linking potassium level at admission with registry data on patient characteristics, laboratory data, redeemed prescriptions, and time of death for the period from August 2009 to August 2011. We estimated hazard ratios for all-cause mortality within 0 to 7 days and 8 to 30 days after admission, comparing patients with hypokalemia at admission (plasma [K+] level <3.4 mmol/L) with patients with eukalemia at admission ([K+] level of 3.4-3.8 mmol/L).

      Results

      Hypokalemia occurred in 16.8% of first-time admissions (n = 2011). It was associated with an adjusted hazard ratio [HR] of 1.34 (95% confidence interval [CI], 0.98-1.85) for 7-day mortality and 1.56 (95% CI, 1.18-3.06) for 8- to 30-day mortality. Among patients with more severe hypokalemia (plasma [K+] <2.9 mmol/L), the adjusted HR was 2.17 (95% CI, 1.34-3.49) for 7-day mortality and 1.90 (95% CI, 1.18-3.06) for 8- to 30-day mortality. Prognostic factors for both 7-day and 8- to 30-day mortality among hypokalemic patients were increasing age and Charlson Comorbidity Index, whereas there was no prognostic effect of current diuretic or beta-agonist use.

      Conclusions

      In a mixed population of hospitalized medical patients, hypokalemia is common, and plasma [K+] <2.9 mmol/L is associated with increased 7-day and 8- to 30-day mortality.

      Keywords

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      Linked Article

      • Hypokalemia: A Marker of Covert Bulimia Nervosa
        The American Journal of MedicineVol. 128Issue 9
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          I read with great interest the article by Jensen et al,1 entitled “Hypokalemia in Acute Medical Patients: Risk Factors and Prognosis.” One wonders if some of the “younger” patients in this study actually had covert bulimia nervosa, wherein hypokalemia is common and generally associated with metabolic alkalosis. Although bulimia nervosa has a much lower mortality rate compared with anorexia nervosa, it does have an elevated rate, likely because of the many medical complications associated with purging behaviors and the resultant common electrolyte and acid-base disorders.
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