We obtained midstream or catheterized urine samples (4 mL in a standard sterile urinary container) for analysis performed within 30 minutes of sample collection. We performed a dipstick analysis (Combur Test M, Roche Diagnostics, Germany) and recorded the amount of urinary blood, protein, and leukocytes. For microscopy, the remaining portion of urine was centrifuged at 5000 rpm for 10 minutes and the sample was examined by microscope under low (×100) and high (×400) power. We assessed the presence and number of leucocytes, red cells and casts. Serum was analyzed for creatinine against a standard reference range of 66–106 μmol/L.
For patients with a raised serum creatinine (defined as 26.5 μmol/L or more above the upper limit of the standard reference range), we repeated the creatinine test within 48 hours of the first test collection to demonstrate rapidly changing values. The highest value of creatinine was used to stage the patient using the Acute Kidney Injury Network (AKIN) into stages 1, 2, or 3 [7 (link)].
For patients with a raised serum creatinine (defined as 26.5 μmol/L or more above the upper limit of the standard reference range), we repeated the creatinine test within 48 hours of the first test collection to demonstrate rapidly changing values. The highest value of creatinine was used to stage the patient using the Acute Kidney Injury Network (AKIN) into stages 1, 2, or 3 [7 (link)].