Blood used for transfusions may have too high potassium concentrations due to routine radiation treatment, which could be hazardous to babies, pregnant mothers and those with impaired kidney function or immunocompromised disease.

The transfusion centre of Newcastle General Hospital measured potassium blood concentrations after a child with leukaemia receiving a blood transfusion died and two other reports noted raised potassium concentrations in irradiated blood.

Blood components are routinely irradiated supposedly to reduce the risk of graft versus host disease induced in transfusing immunocompromised patients with foreign blood. It has always been assumed that irradiation was harmless to red cells and had little effect on the function of the various components.

Newcastle found that irradiated blood had double the potassium concentration of non irradiated blood after nine days, with a marked decrease in sodium concentration levels.

The centre called for policies to be drawn up on the safe use of irradiated blood, including the possibility of using it immediately after irradiation, when the potassium concentration is still similar to that of ordinary blood.