Authors’ Reply

• COVID AKI
• COVID-19

Zijlstra et al.¹ question whether delay to postmortem biopsy and ensuing tissue autolysis could have interfered with our molecular diagnostics. They ask how long after death were biopsies done in our study, and suggest that studies using more rapid postmortem biopsy might be more productive. Supplemental Table 1, included in our paper,² provided the times between death and biopsy. Out of 12 cases, 11 were biopsied within 24 hours postmortem; three were performed within 2.5 hours. The fastest time to biopsy was 1.5 hours. A number of the cases had mild or no autolysis, as seen in Table 1. Similarly, Santoriello et al.³ did not find any clear evidence of viral infection of kidney in a postmortem series of 42 patients, many of whom had mild or absent autolysis. We acknowledge there remains the possibility that postmortem autolysis could interfere with the detection of the virus, although it must be emphasized that, in both of these aforementioned studies, lung specimens from autopsies used as controls were clearly positive for the virus. Corroborating our findings are two series of renal biopsy specimens in living patients with coronavirus disease 2019 included in the same issue of JASN.^4,5 In these series (the majority in patients who had severe AKI), they also found no clear evidence of viral infection of the kidney, by ultrastructural examination in addition to immunohistochemical staining for viral spike and nucleocapsid proteins, and in situ hybridization for severe acute respiratory syndrome coronavirus 2 viral RNA. The conclusions of these four reports, two in living and two in postmortem kidneys, are consistent: it does not appear likely that direct viral infection is a primary contributor to renal dysfunction in patients with coronavirus disease 2019.

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