BackgroundAKI is a manifestation of COVID-19 (CoV-AKI). However, there is paucity of data from the United States, particularly from a predominantly black population. We report the phenotype and outcomes of AKI at an academic hospital in New Orleans.MethodsWe conducted an observational study in patients hospitalized at Ochsner Medical Center over a 1-month period with COVID-19 and diagnosis of AKI (KDIGO). We examined the rates of RRT and in-hospital mortality as outcome measures.ResultsAmong 575 admissions (70% black) with COVID-19 [173 (30%) to an intensive care unit (ICU)], we found 161 (28%) cases of AKI (61% ICU and 14% general ward admissions). Patients were predominantly men (62%) and hypertensive (83%). Median body mass index (BMI) was higher among those with AKI (34 versus 31 kg/m2, P<0.0001). AKI over preexisting CKD occurred in 35%. Median follow-up was 25 (1–45) days. The in-hospital mortality rate for the AKI cohort was 50%. Vasopressors and/or mechanical ventilation were required in 105 (65%) of those with AKI. RRT was required in 89 (55%) patients. Those with AKI requiring RRT (AKI-RRT) had higher median BMI (35 versus 33 kg/m2, P=0.05) and younger age (61 versus 68, P=0.0003). Initial values of ferritin, C-reactive protein, procalcitonin, and lactate dehydrogenase were higher among those with AKI; and among them, values were higher for those with AKI-RRT. Ischemic acute tubular injury (ATI) and rhabdomyolysis accounted for 66% and 7% of causes, respectively. In 13%, no obvious cause of AKI was identified aside from COVID-19 diagnosis.ConclusionsCoV-AKI is associated with high rates of RRT and death. Higher BMI and inflammatory marker levels are associated with AKI as well as with AKI-RRT. Hemodynamic instability leading to ischemic ATI is the predominant cause of AKI in this setting.

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Background. Microscopic examination of the urinary sediment (MicrExUrSed) is an established diagnostic tool for acute kidney injury (AKI). Single inspection of urine during the course of AKI is a mere snapshot affected by timing. We hypothesized that longitudinal MicrExUrSed provides information not identified in a single inspection. Methods. MicrExUrSed was undertaken in patients with AKI stage >= 2 and suspected intrinsic cause of AKI seen for nephrology consultation over a 2-year period. MicrExUrSed was performed on the day of consultation and repeated at a second (2 - 3 days later) and/or third (4 - 10 days later) interval. Cast scores were assigned to each specimen. Chawla scores (CS) 3 to 4 and Perazella scores (PS) 2 to 4 were categorized as consistent with acute tubular injury (ATI), whereas CS 1 to 2 and PS 0 to 1 were categorized as non-diagnostic for ATI (non-ATI). Non-recovering AKI was defined as a rise in serum creatinine (sCr) ≥ 0.1 mg/dL between microscopy intervals. Results. At least 2 consecutive MicrExUrSed were performed in 121 patients [46% women, mean age 61 ± 14, mean sCr at consult of 3.3 +/- 1.9 mg/dL]. On day 1, a CS and PS consistent with non-ATI was assigned to 64 (53%) and 70 (58%) patients, respectively. After a subsequent MicrExUrSed, CS and PS changed to ATI in 14 (22%) and 16 (23%) patients. Thus, 20 - 24% of patients only revealed evidence of ATI after serial MicrExUrSed was performed. Patients with non-recovering AKI were more likely to change their PS to ATI category [odds ratio: 5.8 (CI:1.7-19.3; p=0.005) and positive likelihood ratio: 2.0 (CI: 1.3-2.9)]. Conclusion. Serial MicrExUrSed revealed diagnostic findings of ATI not identified in a single examination. A repeat MicrExUrSed may be warranted in cases of AKI of unclear etiology or not recovering.

Background. Fractional excretion of urinary sodium (FENa) is a widely utilized test to evaluate acute kidney injury (AKI). A low FENa (<1%) is deemed consistent with prerenal azotemia and inconsistent with acute tubular injury (ATI). Muddy brown granular casts (MBGC) on microscopic examination of the urinary sediment (MicrExUrSed) are highly suggestive of ATI. We hypothesized that there is poor concordance between the presence of MBGC and FENa in ATI. Methods. We conducted a prospective observational study in patients with AKI seen during inpatient consultation. We extracted cases who underwent assessment of percentage of low power fields (LPF) with MBGC by MicrExUrSed and concomitant measurement of FENa. Diagnostic concordance between MBGC and FENa as well as prognostic value were examined. Results. Our cohort included 270 patients with 111 (41%) women. Median age was 61 (27-92) and median serum creatinine was 3.7 (1.2-22.0) mg/dL. MBGC were found in 49% (133/270). FENa <1% was found in 50/133 (38%), 38/115 (33%) and 16/45 (36%) of those with >0%, ≥10%, and ≥50% LPF with MBGC, respectively. Concordance between FENa and MBGC for ATI diagnosis was deemed fair (estimated kappa coefficient 0.2), and poor (kappa -0.11) within a subgroup of patients with preexisting chronic kidney disease (n=139). In patients with biopsy-proven ATI (n=49), MBGC had 100% specificity and 100% positive predictive value for ATI. MBGC were associated with greater risk for ≥50% increase in creatinine from baseline at discharge [acute kidney disease (AKD)]. Conclusion. About 2/5 of patients with MBGC presented with FENa <1%. Presence of MBGC was consistent with ATI, as verified by biopsy, and were predictive of AKD. These data suggest that the sole reliance in low FENa to exclude ATI should be abandoned and MicrExUrSed should be pursued for AKI diagnosis.