EPO and chronic kidney disease: Figure 2 shows the comparison of the steady-state ranges of plasma EPO, Hb, reticulocytes, and RBCs across healthy VPs and CKD 1–5 as observed in simulations against patient data. Even though the model parameters were not tuned to match the reticulocyte and RBC ranges for individual stages of CKD, the steady-state values from the model are close to the data obtained from Li et al. (2019) and Sheth and Shah (2016), except reticulocytes for CKD 5 (Nidhi Sheth, 2016; Li et al., 2019).