Refractoriness of Hyperkalemia and Hyperphosphatemia in Dialysis-Dependent Acute Kidney Injury Associated with COVID-19

Abstract

Background: Persistent hyperkalemia (hyperK) and hyperphosphatemia (hyperP) despite renal replacement therapy (RRT) was anecdotally reported in COVID-19 and acute kidney injury (AKI) requiring RRT (CoV-AKI-RRT). However, observation bias could have accounted for the reports. Thus, we systematically examined the rate and severity of hyperK and hyperP in patients with CoV-AKI-RRT in comparison with pre-COVID-19 era. Methods: We identified patients with CoV-AKI-RRT treated with sustained low-efficiency dialysis (SLED) for ≥2 days in March-April 2020. As pre-COVID-19 control, we included patients with AKI treated with SLED who were part of a research database (2018-2019). We examined the rates of hyperK [serum potassium (sK) >=5.5 mEq/L], severe hyperK [sK >=6.5 mEq/L], hyperP [serum phosphate (sP) >=4.5 mg/dL] and moderate or severe hyperP [sP >=7.0-10.0 and >10.0 mg/dL, respectively] as %SLED-days with an event. Results: Along the duration of SLED, the incidence of hyperK was greater in CoV-AKI-RRT (n=64) [mean 19(2)% vs. 14(3)% SLED-days, p=0.002] compared to control (n=60). The proportion of patients with >=1 event of severe hyperK was greater in CoV-AKI [33% vs. 7%, p=0.0004]. The incidence of hyperP was similar between groups [mean 56(4)% vs. 53(5)% SLED-days, p=0.49]. However, the proportion of patients with >=1 event of moderate and severe hyperP was greater in CoV-AKI-RRT [86% vs. 60% (p=0.001) and 50% vs. 18% (p=0.0002), respectively]. Among those with CoV-AKI-RRT, sK and sP correlated with lactate dehydrogenase (LDH) [r=0.31 (p=0.044) and r=0.31 (p=0.043), respectively] whereas hyperP also correlated with shorter SLED runs (hours/run) (r=-0.27, p=0.055). Conclusion: Refractory hyperK and hyperP were more frequent in CoV-AKI-RRT compared to pre-COVID-19 era. Because of the correlation of sK and sP with higher LDH and sP with shorter SLED runs, intracellular ion release from cell injury due to cytokine storm and RRT interruptions may account for the findings.