The Journal of laboratory and clinical medicine
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We reported previously that painful crises in patients with sickle cell anemia are accompanied by striking decreases in the percent of densest red cells (fraction 4) when studied with isopyknic Percoll-Stractan gradients. We report that an alternative to density gradients is the red cell distribution width (RDW), an estimate of red cell size variation measured with a Coulter counter. ⋯ In patients in whom serial measurements of both RDW and fraction 4 (very dense) red cells were taken during crisis, the two measurements declined in parallel. The decrease of RDW is a readily observable and objective laboratory concomitant of painful sickle crisis.