CRP and acute kidney injury: Recently, biomarkers such as serum procalcitonin (PCT), C-reactive protein (CRP), and neutrophil gelatinase-associated lipocalin (NGAL) are established as markers of renal tubular and kidney function.5 Previous studies have found that PCT and NGAL are elevated much earlier than traditional renal function indexes such as blood urea nitrogen and blood creatinine, in the early stage of AKI after cardiac surgery.