Association between the hypokalaemia index based on area over the serum potassium concentration curve and occurrence of acute kidney injury in patients administered liposomal amphotericin B

Background Acute kidney injury (AKI) and hypokalaemia are common adverse events after treatment with liposomal amphotericin B (L‐AMB). Objectives Because excess potassium (K) leakage occurs during renal tubular injury caused by L‐AMB, measuring the decrease in rate of serum K concentration might be more useful to assess the renal impact of L‐AMB than hypokalaemia identified from a one‐point measurement. The effects of a decrease in K concentration and duration of hypokalaemia on AKI were investigated. Methods A ≥ 10% decrease in K concentration from the reference concentration within a 7‐day timeframe was evaluated. The hypokalaemia index, which combines the duration of K concentration lower than the reference and a marked low K concentration, was calculated from the area over the concentration curve. Results Eighty‐six patients were included in the study. The incidences of AKI and decrease in K concentration were 36.0% and 63.9%, respectively. Of patients who developed both adverse events, a decrease in K concentration occurred first in 22 of 26 patients, followed by AKI 7 days later. Hypokalaemia did not increase AKI risk whereas a decrease in K concentration was an independent risk factor for AKI. The hypokalaemia index in patients with AKI was significantly higher than those without AKI (5.35 vs. 2.50 points, p = 0.002), and ≥3.45 points was a significant predictor for AKI. Conclusion A ≥ 10% decrease in the K concentration was a significant factor for AKI in patients receiving L‐AMB therapy. In such patients, dose reduction or alternative antifungals could be considered based on the hypokalaemia index.