Oliguria is a common feature of acute kidney injury (AKI), but should be interpreted in the context of other biochemical markers when diagnosing and monitoring AKI or considering the need for renal support. We report an unusual case of apparent severe oliguria arising as a result of complex urological pathology and discuss how an understanding of creatinine kinetics raised suspicions of an alternative diagnosis. We discuss the problems caused by an over-reliance on urine output or serum creatinine alone when diagnosing and staging AKI and highlight the need for a more holistic approach.