[Analytical and technical reliability of the ELT-8 laser hematologic counter]

The ELT-8 laser haematological cell counter is a fully mechanized instrument, which measures the forward scatter of light from a helium-neon laser caused by suspended particles. The apparatus has high practicability, and uses a very small sample volume of 100 microliters. The operational procedure is simple and quickly learned. In the second year of operation, down time for the instrument was, on average, 8 hours/month. Depending on the parameter, the precision of the measurements are between 0.5 and 4% in series, and 1-9% day-to-day. The highest scatter of results was shown for thrombocyte counting, but this may be due to instability of the control samples. There was no carry over between samples containing different concentrations of any of the measured parameters. Lipaemia and haemolysis of samples can lead to false results or false interpretation of results. Cold agglutinins, active against erythrocytes and thrombocytes, can cause significant interference, and this influence can be recognized from discrepancies between the erythrocyte count and haemoglobin concentration or mean corpuscular volume (MCV), and from the presence of thrombopenia in the absence of clinical symptoms (pseudothrombopenia). In such cases a histogram is useful. The stability of 72 blood samples was investigated during storage for 4 days at 4 degrees C. The erythrocyte count was very stable, whereas thrombocyte and leukocyte counts sometimes showed irregular variations. The apparatus gives a linear response up to the following limiting values: leukocytes 85 X 10(9)/l, erythrocytes 8 X 10(12)/l, thrombocytes 10(12)/l, haemoglobin 230 g/l.(ABSTRACT TRUNCATED AT 250 WORDS)