When to transfuse blood in sickle cell disease? Lessons from Jehovah's Witnesses.

Hemoglobin concentration of 7 to 8 g/dl has been considered an indication for transfusion in the general adult population and has also been frequently applied to patients with sickle cell disease (SCD). Through a review of the case histories of two patients with SCD who were also Jehovah's Witnesses and developed severe anemia, and considering as well the clinical characteristics of this population and the basic physiology of oxygen transport, the appropriateness is questioned of this transfusion "trigger" in patients with SCD. It is suggested for the latter that a Hb of 5.5 g/dl be used as an indication for transfusion except in very specific clinical circumstances.