The investigators will investigate whether new kidney biomarkers can identify patients who are at risk of chronic kidney disease after an episode of moderate / severe acute kidney injury in ICU.

Acute kidney injury (AKI) is a common complication during critical illness and associated with serious short and long-term complications. Participants with AKI have an increased risk of developing dysfunction of other organs, including multi-organ failure, a longer stay in hospital and a higher risk of dying. Survivors remain at risk of complications, even if kidney function initially recovers. In particular, they are at high risk of developing chronic kidney disease, dialysis-dependent end-stage kidney disease and cardiovascular comorbidities. At present, the tools to identify patients at highest risk of chronic kidney disease (CKD) are very limited.

The investigators will recruit participants who had AKI whilst in ICU and are scheduled to be discharged from hospital. Within 3 days of discharge from hospital, blood and urine kidney biomarkers will be measured to explore whether there is a correlation with renal function 3 months later and to identify those at highest risk of CKD. In addition, quality of life at 3 months will be assessed.

Inclusion Criteria:

critically ill adult patients who had AKI stage II or III whilst in ICU and are scheduled to be discharged from hospital

Exclusion Criteria:

1. known pre-existing end-stage kidney disease or advanced CKD (stage 3b or worse)
2. kidney transplant within the last 12 months
3. known primary renal disease
4. discharge from hospital for end-of-life care
5. transfer to another health care institution for ongoing in-patient care
6. not expected to survive for 3 months
7. pregnancy
8. lack of capacity to give consent
9. receiving regular dialysis at hospital discharge
10. CKD stage 3 or worse at hospital discharge

critically ill adult patients in the ICU