Coronavirus disease 2019 (COVID-19) can lead to clinically significant multisystem disorders that also affect the kidney. According to recent data, renal injury in the form of thrombotic microangiopathy (TMA) in native kidneys ranks third in frequency. Our review of global literature revealed 46 cases of TMA in association with COVID-19. Among identified cases, 18 patients presented as thrombotic thrombocytopenic purpura (TTP) and 28 cases presented as atypical hemolytic uremic syndrome (aHUS). Altogether, seven patients with aHUS had previously proven pathogenic or likely pathogenic genetic complement abnormalities. TMA occurred at the time of viremia or even after viral clearance. Infection with COVID-19 resulted in almost no or only mild respiratory symptoms in the majority of patients, while digestive symptoms occurred in almost one-third of patients. Regarding the clinical presentation of COVID-19-associated TMA, the cases showed no major deviations from the known presentation. Patients with TTP were treated with plasma exchange (88.9%) or fresh frozen plasma (11.1%), corticosteroids (88.9%), rituximab (38.9%), and caplacizumab (11.1%). Furthermore, 53.6% of patients with aHUS underwent plasma exchange with or without steroid as initial therapy, and 57.1% of patients received a C5 complement inhibitor. Mortality in the studied cohort was 16.7% for patients with TTP and 10.7% for patients with aHUS. The exact role of COVID-19 in the setting of COVID-19-associated TMA remains unclear. COVID-19 likely represents a second hit of aHUS or TTP that manifests in genetically predisposed individuals. Early identification of the TMA subtype and appropriate prompt and specific treatment could lead to good outcomes comparable to survival and recovery statistics for TMA of all causes.

Excessive release of cytokines during systemic inflammatory response syndrome (SIRS) often leads to refractory hypotension and multiple organ failure with high mortality. Cytokine removal with hemoadsorption has emerged as a possible adjuvant therapy, but data on interleukin-6 (IL-6) reduction and outcomes in clinical practice are scarce. We aimed to evaluate the effect of CytoSorb hemoadsorption on laboratory and clinical outcomes in shocked patients with SIRS. We designed a retrospective analysis of all patients with SIRS treated with CytoSorb in intensive care units (ICU). IL-6, laboratory and hemodynamic parameters were analyzed at approximate time intervals during CytoSorb treatment in the whole cohort and in a subgroup with septic shock. Observed and predicted mortality rates were compared. We included 118 patients with various etiologies of SIRS (septic shock 69%, post-resuscitation shock 16%, SIRS with acute pancreatitis 6%, other 9%); in all but one patient, CytoSorb was coupled with renal replacement therapy. A statistically significant decrease in IL-6 and vasopressor index with an increase in pH and mean arterial pressure was observed from 6 h onward. The reduction of lactate became significant at 48 h. Results were similar in a subgroup of patients with septic shock. Observed ICU and in-hospital mortalities were lower than predicted by Sequential Organ Failure Assessment (SOFA) (61% vs. 79%, p = 0.005) and Acute Physiology and Chronic Health Evaluation (APACHE) II (64% vs. 78%, p = 0.031) scores. To conclude, hemoadsorption in shocked patients with SIRS was associated with a rapid decrease in IL-6 and hemodynamic improvement, with improved observed vs. predicted survival. These results need to be confirmed in a randomized study.

Coronavirus disease 2019 (COVID-19) has spread tremendously since its first appearance in December 2019. Infected individuals can experience a wide range of systemic complications, including thrombotic microangiopathy (TMA). Like the other forms of TMA, COVID-19-associated TMA is characterized by thrombocytopenia, hemolytic anemia, and organ failure (such as acute kidney injury). The role of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in COVID-19-associated TMA is most probably dual: it can act either as a trigger to an underlying condition or as a cause of TMA. As opposed to the majority of other reported cases, it may be that in our case COVID-19 was the only cause of TMA. We present a case of a 32-year-old previously healthy man who was treated for acute kidney injury associated with TMA, which we believe was caused by COVID-19. Thrombotic thrombocytopenic purpura, as well as other possible known causes of typical and atypical hemolytic-uremic syndrome, was excluded. During his hospitalization, three negative nasopharyngeal swabs for SARS-CoV-2 were obtained, but serological tests showed the presence of IgG and IgA antibodies. After initial treatment known to be helpful in other forms of TMA (therapeutic plasma exchange and methylprednisolone), his renal function and platelet count recovered completely. Our case illustrates the importance of quickly recognizing this life-threatening complication of COVID-19 and using treatment that has been shown to be beneficial in other forms of TMA. Future studies of the pathophysiology and subsequent targeted treatment of this novel disease are needed.