Safety and effectiveness of a modification of diet in renal disease equation-based potassium replacement protocol.

Background: No data exist regarding the safety and effectiveness of a potassium replacement protocol for hospitalized patients when potassium replacement dosing regimens (KRDRs) are adjusted to Modification of Diet in Renal Disease estimation of glomerular filtration rate (MDRD GFR).

Objective: To evaluate the effectiveness and safety of a potassium replacement protocol in which KRDRs are prescribed based on MDRD GFR and serum potassium deficiency (Kdef).

Methods: Patients prescribed the potassium replacement order set were identified in a retrospective fashion. Serum potassium, prescriber-defined goal serum potassium, and MDRD GFR data were collected for patients who received protocol KRDRs. The KRDR to be administered is selected based on Kdef (goal serum potassium minus measured serum potassium) of 0.1-0.2, 0.3-0.5, or more than 0.5 mEq/L and the patients' MDRD GFR of greater than 70, 40-70, or less than 40 mL/min/1.73 m(2) (any patient undergoing dialysis is included in the <40 mL/min/1.73 m(2) group). Efficacy was evaluated by determining the change in serum potassium level (Delta K) following potassium replacement, the number of KRDRs needed to achieve goal serum potassium, and the milliequivalents of potassium needed to achieve goal serum potassium levels. Safety was assessed by the incidence of serum potassium values greater than 5.0 mEq/L following replacement.

Results: One hundred forty-nine patients were evaluated. There were 184 protocol initiations and 257 KRDRs administered to achieve goal serum potassium levels. The DeltaK was 0.50 +/- 0.40 mEq/L (mean +/- SD) following KRDR. The Delta K was similar between MDRD GFR groups. One hundred thirty six (73.9%) protocol initiations required 1 KRDR, and 168 (91.3%) protocol initiations required 1 or 2 KRDRs to achieve goal serum potassium. Patients whose MDRD GFR was 40-70 mL/min/1.73 m(2) were less likely to achieve goal serum potassium value after 1 KRDR (58.2% vs 79.6% >70 group and 84.6% <40 group). This was true regardless of the patient's goal serum potassium. One (0.54%) serum potassium greater than 5.0 mEq/L occurred following a KRDR.

Conclusions: Our potassium replacement protocol based on MDRD GFR and Kdef effectively corrects hypokalemia. Fewer protocol initiations achieved goal serum potassium levels in the group with MDRD GFR 40-70 mL/min/1.73 m(2). Hyperkalemia rarely occurred following KRDR.