We read with great interest the article published by Tarragón-Blanca et al, whose aim was to describe the different presentations of acute kidney injury (AKI) requiring intervention by the nephrologist, its clinical course and possible strategies for early detection and nephroprotection. The authors concluded that hypovolaemia and dehydration are the most common causes of AKI in patients with COVID-19, as well as a poorer respiratory, analytical and renal prognosis. They also recommended monitoring of renal markers, in addition to personalised management of blood volume, as these may be decisive in preventing AKI1.

In the study, an updated clinical correlation was rightly made in the description of patients with COVID-19 infection in relation to the WHO classification and CURB-65, and the staging of acute kidney injury according to the KDIGO guidelines.

The therapeutic strategy for AKI continues to be both conventional renal replacement therapy and continuous veno-venous haemodiafiltration, positive reinforcement on our part for differentiating the clinical course of the patient associated with COVID-19 infection. They even compare the discharge of patients with AKI on admission and in-hospital AKI2.

One of the weaknesses of the study is the small sample size, as type II error can occur, leading to false negatives being obtained, which could exclude variables that need to be taken into account. Elsewhere, in the description of the renal failure, a previous nephropathy could be considered associated with its aetiology, and the clinical course could be compared in in-hospital AKI associated with COVID-19 infection3.

In addition, attention should be given to the differences between the increase in laboratory standards such as creatinine, urea, haematuria and proteinuria from previous episodes of nephropathy related to its aetiology, and in-hospital renal failure3,4.

Hospital outcomes could include the duration of acute kidney injury and its relationship with the patient's hospital stay, whether they had AKI on admission or in-hospital5.

We congratulate the authors for their published work, as it provides valuable information on the association of acute kidney injury with COVID-19, while also taking the follow-up by nephrologists into account. In addition, it broadens the panorama beyond mere parenchymal involvement by SARS-CoV-2, while being the first study to analyse a Spanish cohort.