Diagnosis of AKI Clinical evaluation, including review of prescription and over-the-counter drugs and exposure to iodinated IV contrast Serum creatinine Urinary sediment Urinary diagnostic indices Urinalysis and assessment of urine protein Postvoid residual bladder volume and / or renal ultrasonography if postrenal cause suspected Acute kidney injury (AKI) is suspected when urine output falls or serum blood urea nitrogen (BUN) and creatinine rise.