Hamburg Acute Kidney Injury Study (HAKIS)

Inclusion Criteria: * Hospitalized individuals with acute kidney injury (AKI), defined by the 2012 Kidney Disease: Improving Global Outcomes (KDIGO) criteria or hospitalized individuals with acute illness who have not developed AKI (control group) * Age ≥ 18 years at time of enrollment * Written informed consent provided by the participant or, in participants lacking decision-making capacity, by a legal representative or healthcare proxy, where available. Participants lacking decision-making capacity without an available legal representative or healthcare proxy may be enrolled if participation is not contrary to their presumed wishes, in accordance with the ethics committee-approved consent procedure. Written informed consent is subsequently sought from the participant upon regaining decision-making capacity or from a legal representative, as applicable. Exclusion Criteria: * None