Refractoriness of hyperkalemia and hyperphosphatemia in dialysis-dependent AKI associated with COVID-19

ABSTRACT

Background: There have been anecdotal accounts of an unusual incidence of persistent hyperkalemia (hyperK) and hyperphosphatemia (hyperP) in patients with COVID-19 and acute kidney injury (AKI) (CoV-AKI) despite renal replacement therapy (RRT). However, an observation bias could not be discarded. Thus, we examined the rate and severity of hyperK and hyperP in patients with CoV-AKI actively treated with RRT. Methods: Among 161 patients with CoV-AKI, we selected those who underwent RRT by sustained low efficiency dialysis (SLED) for ≥2 days (n=64). A database of patients with AKI on SLED who underwent urinary sediment microscopy (Sedi-AKI cohort, 2017-2019, n=60) served as control (non-CoV-AKI). We examined the rate of hyperK [serum potassium (sK) ≥ 5.5 mEq/L], severe hyperK [sK ≥ 6.5 mEq/L], hyperP [serum phosphate (sP) ≥ 4.5 mg/dL], moderate hyperP [sP ≥ 7.0-10.0 mg/dL] and severe hyperP [sP >;10.0 mg/dL] as % SLED-days with an event. Results: Median age were similar 60 (39-84) and 58 (22-88) years for CoV-AKI and non-CoV-AKI, respectively. Black race (77% vs. 30%;p<0.0001) and male sex (78% vs. 61%;p=0.04) were more common in CoV-AKI. Ischemic ATI was the presumed cause of AKI in 85% and 82% of the CoV-AKI and non-CoV-AKI, respectively. Along the duration of SLED, the incidence of hyperK was greater in CoV-AKI [mean 19 ± 2% vs. 14 ± 3% SLED-days, p=0.002]. 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 were 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 were greater in CoV-AKI [86% vs. 60% (p=0.001) and 50% vs. 18%, (p=0.0002)]. In CoV-AKI, sK and sP correlated with lactate dehydrogenase (LDH) [R=0.305 (p=0.044) and R=0.307 (p=0.043), respectively] but not with creatine kinase;and hyperP events correlated with shorter SLED runs (hours/run) (R=-0.268, p=0.055). Conclusions: HyperK and hyperP refractory to RRT (by SLED) were more frequent in CoV-AKI compared to other forms of AKI in the pre-COVID-19 era. Because of the correlation of sK and sP with higher LDH and shorter SLED runs, intracellular ion release from cell injury due to cytokine 'storm' and RRT interruptions may play a role.