Here we are managing a patient on dialysis with anaemia using a drug that stimulates red cell production in the bone marrow, called an erythropoiesis stimulating agent or ESA (eg EPO)
THe Haemoglobin (Hgb) level is measured every two weeks and if too high the dose is decreased, and if too low, the dose is increased, according to a dosing protocol
To understand the effect of the drug dose we need to map the process of red blood cell production, erythropoiesis. Stem cells form Erythroid colony forming units (E CFUs) and erythroblasts develop over time into reticulocytes which are released into the circulating blood as reticulocytes which age into mature Red Blood Cells
Red Blood Cells age over a few months and are removed from the blood, mostly by the spleen
The number of circulating red blood cells determines the level of the Haemoglobin test result
The Drug dose effect can be represented as changing the Erythroid Colony Creation Rate and the inflow of red blood cell precursors. The direction of change in creation rate is the same as the direction of change in dose.
To calculate this impact of the drug dose we can calculate the effect of the dose on a base creation rate.
To make the situation more interesting, we can add the effect of bleeding. This is represented simply as an extra leakage of both red blood cells and reticulocytes out of the Red Blood Cell Chain
The simulation is now running and pausing at 14 days. Adjust the dose using the slider on the right of the graph. Run the simulation using the blue play arrow at the bottom left of the display The simulation will pause again every 14 days for you to adjust the dose and run the simulation again. Be aware that an episode of bleeding might occur!