Examples of Iohexol concentrations achieved during Method B (CILDI). Different steady state concentrations were observed in subjects 5 and 15. GFR in subject 5 was 127.7 mL/min/1.73 m2, and GFR in subject 15 was 62.2 mL/min/1.73 m2. Concentrations and time were plotted on a 2-phase exponential decay curve, using Graphpad Prism®, version 5.0d (Graphpad software, Inc.). The black line connects the Iohexol concentrations, the red line depicts the steady state concentration.