Acute kidney injury in SARS-CoV-2 infected patients

Fanelli, Vito; Fiorentino, Marco; Cantaluppi, Vincenzo; Gesualdo, Loreto; Stallone, Giovanni; Ronco, Claudio; Castellano, Giuseppe

As described, AKI developed in average 9 days after admission together with secondary infections and acute cardiac damage [2, 3] . Age, severity of illness, and the presence of diabetes are risk factors for AKI in ARDS patients; moreover, the severity of AKI is further associated with BMI and history of heart failure also defined as cardio-renal syndrome [7] . Similar observations, including the presence of diabetes, have been reported for COVID-19-associated ARDS. All these risk factors added to the increased incidence of AKI in elderly lead to the hypothesis that renal complications are predominant in patients with pre-existing chronic impairment of kidney function that is difficult to evaluate based only on serum creatinine levels, thus claiming for the use of new biomarkers of early kidney injury. Therefore, determining the risk for developing AKI in SARS-CoV-2 infected patients or progressing to severe AKI requiring renal replacement therapies [8] is an important step for the patient's prognosis and for early implementation of preventative and protective measures [7, 9] . Classical assessment of AKI is still based on serum creatinine and urine output, but they represent only indicators of established kidney damage. In this scenario, much attention has focused on novel biomarkers in the last years, particularly on markers of acute tubular stress/damage such as TIMP-2 (tissue inhibitor of metalloproteinase 2) and IGFBP7 (insulin-like growth factor binding protein 7) and their product [TIMP-2]*[IGFBP-7] identified using the NephroCheck Test [10] . This test has been set for the prediction of moderate to severe AKI within 12 h after ICU admission, and it is the only one approved by the Food and Drug Administration in this setting [11] . Several evidences suggested that the application of NephroCheck may help physicians to identify patients with tubular stress, before kidney dysfunction is manifested [12] . Critically ill patients are indeed exposed to several potential kidney insults in this setting (SARS-CoV-2 infection, drug nephrotoxicity, contrast media) during ICU stay; serial measurements of these biomarkers may be a useful tool to predict AKI during the first 7 days of ICU stay [13] .