Acquired or secondary haemochromatosis can be the result of another disease or condition that causes an overload of iron from multiple blood transfusions, along with certain types of anemia, chronic liver diseases, oral iron pills and long term kidney dialysis. For those who receive numerous transfusions, it is not unusual for the ferritin level to rise to higher than normal, indicating that the body is storing too much iron in various tissues that can cause morbidity or even mortality. High levels of ferritin do not affect the amount of iron in the body, although a single unit of transfused blood contains approximately 250 mg of iron and when the ferritin level is too high a series of venesections may be required to reduce it. In this case, blood is removed from the circulatory system, up to 500ml at a time, until the ferritin level returns to within the normal range The models derived here enable the medical practitioner to estimate the number of venesections that are likely to be required based on the current ferritin level, gender, height, weight, the amount of blood removed at each session and the desired ferritin level. It is found that the drop in ferritin level after a series of venesections follows a negative exponential distribution and numerical examples are provided to illustrate the equations.