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Abstract: PO0483

Elevation in Red Cell Distribution Width (RDW) Is a Risk Factor for Future Hyponatremia and Hypokalemia

Session Information

Category: Anemia and Iron Metabolism

  • 200 Anemia and Iron Metabolism


  • Tanaka, Hiroshi, Mihara Sekijuji Byoin, Mihara, Hiroshima, Japan

Elevation in red cell distribution width (RDW), a marker of size variance in red blood cells, recently has been reported to predict mortality, future cardiovascular events, and faster CKD progression. Putative mechanisms in RDW elevation include factors such as inflammation, aging, oxidative streess or malnutrition. It has not been clearly reported whether elevation in RDW has any significant impact on future electrolyte metabolism.


A hospital-wide study with all the laboratory data for a period of 4 years and 2 months was conducted. First, for each patient, hemoglobin (Hb) measurements of the initial 365 days were retrieved and the maximum RDW was obtained. Then the latest measurements of serum sodium (Na) and potassium (K), at least 365 days apart from the initial Hb and RDW measurement, were obtained. Prevalence and odds ratio (OR) of hyponatremia and hypokalemia were calculated for each quartile of RDW. Statistical analysis was performed with R 3.6.0 on Ubuntu and with Microsoft Excel.


A total of 5,537 patients were included in the study. Hb ranged from 7.7 to 20.2 (median 13.4) g/dL, MCV 55.7-124.5 (93.1) fL, and RDW 10.1-34.6 (12.7)%. Hyponatremia (<130 mEq/L) was observed in 2.65%/1.10%/0.49%/0.71% in patients in each quartile of RDW (from high to low; chi-squared, P <0.001); Patients in the highest quartile of RDW had hyponatremia with OR of 3.80 when reference was set to the lowest quartile of RDW. Hypokalemia (<3.5 mEqL) was observed in 6.99%/4.02%/2.17%/1.89% in each quartile of RDW (chi-squared, P <0.001); Patients in the highest quartile of RDW had OR of 3.90 as the reference at the lowest quartile of RDW. Likewise, in patients with the highest quartile of RDW, more severe hyponatremia (<125 mEq/L) and hypokalemia (<3.0 mEq/L) were seen in 0.61% (OR 2.59) and 1.49% (OR 19.2), respecively.


Elevation in RDW is a risk factor for future development of hyponatremia and hypokalemia