LCN2 and acute kidney injury: Higher levels of all 5 log transformed biomarkers were significantly associated with duration of AKI in univariable models, which persisted for all biomarkers except urine NGAL, after adjusting for confounders including age, sex, white race, elective surgery, cardiopulmonary bypass time, pre-operative eGFR, diabetes, hypertension, congestive heart failure, myocardial infarction, surgery type, and center.