Hematologic and red cell analyses in hereditary spherocytosis (HS).
(A) Osmotic gradient ektacytometric profiles of blood samples. The deformability profiles of red cells from nonaffected newborns span the dotted area, whereas those of red cells from newborns with HS fall within the hatched area. DImax indicatesmaximum deformability index, a measure of red cell surface area; and Omin, the osmolality at which the deformability value reaches a minimum in the hypotonic region of the gradient, a measure of osmotic fragility of red cells. There is a decrease in DImaxvalues (B) in children with HS, reflecting membrane surface-area loss, and a right shift of the deformability curve in the hypotonic region (Omin), reflecting a decreased ratio of surface area to volume in the HS red cells (increased osmotic fragility) (C). Solid diamonds indicate affected children; and open diamonds, nonaffected children. The percentage of hyperdense cells (cell hemoglobin (Hb) concentration > 410 g/L) (D), mean corpuscular hemoglobin concentration (MCHC) (E), and hemoglobin concentration distribution width (HDW) (F) are higher in HS. In contrast, there is a large overlap between red cell volume distribution width (RDW) in newborns with HS and that in nonaffected newborns (G). The range of normal values in adults and children (B and C) or age-matched newborns (E-G) is indicated by dotted lines. The normal threshold value for percentage of hyperdense cells is indicated by the dotted line in D.
