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

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