Abstract

Automated full blood counters measuring the size and haemoglobin concentration of individual red cells by high and low angle light scatter can provide estimates of the percentage of cells which are abnormal in either or both of these variables. The hypothesis that an increase in the number of large cells with a reduced haemoglobin content ("hypochromic macrocytes") was indicative of a reticulocytosis was investigated. A correlation was shown between the percentage of hypochromic macrocytes and the reticulocyte count. This correlation was too weak to allow the actual reticulocyte percentage to be predicted from the percentage of hypochromic macrocytes. An increased percentage of hypochromic macrocytes, however, often indicates an increased reticulocyte count and thus serves to chart the haematologist to this possibility.