[Reticulocytes--new possibilities with automated counting].

A fully automated reticulocyte counter, Sysmex R-1000 has been evaluated at three Norwegian hospitals. The instrument measures fluorescence-labelled RNA in the reticulocytes by flow cytometry. It also generates information on reticulocyte maturity. Instrument precision was superior to that achieved with the routine visual counting method. Samples preserved at room temperature remain stable for one day, whereas samples preserved at 5 degrees C remain stable for four days. An increasing number of reticulocytes is often the first sign of marrow regeneration after bone marrow transplantation or treatment of leukaemia with cytostatica. In patients with chronic renal failure who are receiving erythropoietin, the increase in reticulocytes is seen within days, and precedes the increase in haemoglobin by 2-3 weeks.