Brain O2 reserve in sickle cell disease

In this issue of Blood, Fields and colleagues demonstrate that patients with sickle cell disease (SCD) on hydroxyurea have lower cerebral oxygen extraction fraction (OEF) than similar patients not receiving disease-modifying therapy.(1) Although hydroxyurea has become the standard of care for young children with SCD, its ability to protect the white matter from silent strokes remains unknown. In the Creteil cohort, SCD patients had access to regular TCD screening since birth, and hydroxyurea was routinely administered to children with frequent vasoocclusive crises. Despite this, the prevalence of silent strokes was 37.4% by the age of 14 in this cohort.(2) With the increasing use of hydroxyurea, in lieu of transfusion therapy, for SCD patients with abnormal transcranial Doppler results,(3) there is appropriate anxiety about hydroxyurea's cerebral protection.