[Usefulness of cytometry based on the diffraction of a laser beam in evaluating spherocytosis]

Thirty four cases of hereditary spherocytosis were studied by means of laser diffraction cytometry. The cases were grouped for study in accordance to previous splenectomy or not, familial involvement or not, and, in patients not subjected to splenectomy, severity of the clinical course. The values used to assess the presence of spherocytosis were those measuring the haemoglobin concentration within red cells, such as CH (directly estimated mean corpuscular haemoglobin), HDW (standard deviation of the distribution according to haemoglobin concentration) and % hyper (percentage of cells with haemoglobin concentration higher than 41 g/dL). The variables attained were statistically analysed by means of non-parametric tests. In patients with spherocytosis, MCV, MCHC, RDW, HDW, % hyper, and CH were significantly different from the normal group. This method points to the presence of spherocytosis by means of CH, HDW and % hyper. A reduction of the limit of haemoglobin concentration used to define % hyper (41 g/dL) could improve the sensitivity of the instrument for the diagnosis of the mild forms, which is often more difficult.