Phlebotomy (venesection)

Therapeutic phlebotomy removes 250 to 500 millilitres of blood at a time to lower the haematocrit, usually weekly at first and then every few months once the target is reached. It works by removing red cells and by making the patient iron-deficient, which slows red-cell production. Its drawbacks are the iron deficiency itself (fatigue, restless legs), the time and needle burden, and the fact that counts rebound between sessions; drugs such as rusfertide aim to replace it.