Figure 3

A significant inverse correlation (r = − 0.59, 95 % CI - 0.72 to - 0.43, p < 0.001) between postnatal age (days) and urinary creatinine concentration (enzymatic method, mg/dL) is documented, likely in part reflecting the oliguria and the associated higher urinary creatinine concentrations in early neonatal compared to late neonatal life. (X-axis = postnatal age (days, PNA); Y-axis = creatinine in urine, enzymatic, mg/dL).