An evaluation of the Haema-Count MK-40 blood counting system

The Haema-Count MK-40, a semiautomated blood counting system, determines hemoglobin, erthrocyte count, leukocyte count, and hematocrit values of blood cell suspensions prepared with a small automatic pipetter-diluter. It is similar to the MK-3, which the authors previously evaluated, but has automatic coincidence correlation and a modified prime and rinse cycle. Its performance was compared with those of standard methods, i.e., the single-channel Coulter Counter and manual cyanmethemoglobin and microhematocrit methods. Precisions for hemoglobin determinations and for leukocyte and erythrocyte counts were equal to those of the reference (comparative) methods. Patients comparisons for those determinations had only small intermethod variability and small clinically insignificant biases. The hematocrit channel was the least precise. With a modified method of calibration, the authors obtained patient comparisons without statistically significant bias from the microhematocrit. Calibration was stable for all channels during the course of the study.