COVID-19 infection and renal injury: where is the place for acute interstitial nephritis disease?

COVID-19; Nefritis tubulointersticial aguda; Biòpsia de ronyóCOVID-19; Nefritis tubulointersticial aguda; Biopsia de riñónCOVID-19; Acute tubulointerstitial nephritis; Kidney biopsyNovel coronavirus disease infection (coronavirus disease 2019, COVID-19) was declared a global pandemic in March 2020 and since then has become a major public health problem. The prevalence of COVID-19 infection and acute kidney injury (AKI) is variable depending on several factors such as race/ethnicity and severity of illness. The pathophysiology of renal involvement in COVID-19 infection is not entirely clear, but it could be in part explained by the viral tropism in the kidney parenchyma. AKI in COVID-19 infection can be either by direct invasion of the virus or as a consequence of immunologic response. Diverse studies have focused on the effect of COVID-19 on glomerulonephritis (GN) patients or the ‘novo’ GN; however, the effect of COVID-19 in acute tubulointerstitial nephritis (ATIN) has been scarcely studied. In this article, we present five cases with different spectrums of COVID-19 infection and ATIN that may suggest that recent diagnosis of ATIN is accompanied by a worse clinical prognosis in comparison with long-term diagnosed ATIN.This research was funded by ISCIIII-FEDER and ISCIII-RETICS REDinREN, grant number PI17/00257, PI21/01292, RD16/0009/0030, and RICORS RD21/0005/0016. Enfermedad Glomerular Compleja del Sistema Nacional de Salud (CSUR), enfermedades glomerulares complejas