Transfusion-associated graft-versus-host disease, transfusion-associated hyperkalemia, and potassium filtration: advancing safety and sufficiency of the blood supply.

Irradiation of cellular blood components is well established as a countermeasure against transfusion-associated graft-versus-host disease (TA-GVHD). Unintended consequences of ionizing radiation are also well established. The red cell "storage lesion" – a progression of metabolic, functional, and morphological changes – may be exacerbated by irradiation rates and doses typically used for TA-GVHD prophylaxis. With or without irradiation, a storage lesion change of clinical concern is the accelerated egress of intracellular potassium. ATP depletion during storage limits the activity of the red cell membrane's sodium-potassium pump (Na,K-ATPase), which normally maintains intracellular potassium (K+) at levels 30–40 times higher than the extracellular milieu. The natural diffusion of potassium down this concentration gradient proceeds faster if the cell membrane is damaged, and oxidative damage to cellular membranes and membrane proteins – including Na,K-ATPase – is an effect of ionizing radiation. Preventing transfusion-related hyperkalemia is a reason for limiting the shelf life of irradiated red cells. In the absence of specific measurements to assess storage lesion in a particular unit of blood, and in the absence of specific interventions at the time of transfusion to mitigate effects of storage lesion, it is consistent with the precautionary principle to put conservative limits on a blood component's shelf life. On the other hand, both the safety and sufficiency of a nation's blood supply might be improved by interventions that benefit specific recipients when they are transfused, and benefit future patients by extending the allowable shelf life of blood components. Potassium filtration of irradiated red blood cell components is one such intervention. [ABSTRACT FROM AUTHOR]