To collect and process urine samples from critically ill subjects for use in assessing the effects of various urine sample freezing and storage conditions on biomarker test results.

Inclusion Criteria:

1. Males and females 21 years of age or older

2. Subjects must be enrolled (first study-specific sample collection) within 24 hours of ICU admission

   • Subjects enrolled from ED or Floor must be admitted to the ICU within 24 hours of enrollment
   • Subjects enrolled in the ICU must have been admitted to the ICU or transferred into the study ICU from another ICU no more than 24 hours prior to enrollment

3. Expected to remain in the ICU for at least 48 hours after enrollment

4. Use of indwelling urinary catheter as standard care expected for at least 48 hours after enrollment

5. Subject (or authorized representative)able and willing to provide written informed consent for study participation

Exclusion Criteria:

1. Special populations including children, pregnant women, and prisoners
2. Previous renal transplantation
3. Already receiving dialysis (either acute or chronic) or in imminent need of dialysis at the time of enrollment
4. Known infection with human immunodeficiency virus (HIV) or active hepatitis (acute or chronic)
5. Subjects with a history of chronic kidney disease (CKD) without a baseline serum creatinine value (baseline within 6 months of enrollment)
6. Previously provided a urine sample and enrolled in this study

Critically-ill adult subjects at risk for acute kidney injury.