Blood samples were collected via a central venous catheter and urine samples were collected via a Foley catheter, at 0, 3, 6, 12, 24, and 48 h after admission to the burn intensive care unit. The blood NGAL levels were measured with the Triage NGAL reagent and Triage Meter (Alere Healthcare, San Diego, CA, USA). The serum cystatin C levels were measured according to a turbidimetric immunoassay method with the HiSense cystatin C kit (HBi, Anyang, Korea) and Hitachi 7600 analyzer (Hitachi, Tokyo, Japan). The serum and urine creatinine levels were measured according to an enzymatic method with the Cica Creatinine reagent (KANTO Chemical, Tokyo, Japan) and Hitachi 7600 analyzer (Hitachi, Tokyo, Japan).
For the urine NGAL analysis, urine specimens were transferred to centrifuge tubes and centrifuged at a relative centrifugal force ≥ 400 for a minimum of 5 minutes; the supernatants were stored at -70°C prior to batch analysis. After thawing, the specimens were mixed and centrifuged at 2,500 to 3,000 × g for 10 minutes prior to use, to remove any particulate matter and ensure consistency in the results. The urine NGAL levels were measured in a chemiluminescence immunoassay with an Architect i2000SR analyzer (Abbott Diagnostics, Abbott Park, IL, USA) and a dedicated urine NGAL reagent (Abbott Diagnostics). All measurements were performed according to the manufacturers’ instructions.
For the urine NGAL analysis, urine specimens were transferred to centrifuge tubes and centrifuged at a relative centrifugal force ≥ 400 for a minimum of 5 minutes; the supernatants were stored at -70°C prior to batch analysis. After thawing, the specimens were mixed and centrifuged at 2,500 to 3,000 × g for 10 minutes prior to use, to remove any particulate matter and ensure consistency in the results. The urine NGAL levels were measured in a chemiluminescence immunoassay with an Architect i2000SR analyzer (Abbott Diagnostics, Abbott Park, IL, USA) and a dedicated urine NGAL reagent (Abbott Diagnostics). All measurements were performed according to the manufacturers’ instructions.