Coulter S hematocrit and microhematocrit in polycythemic patients

Falsely high microhematocrits are found when compared to Coulter S hematocrit levels. This increase is exaggerated when hematocrit levels are increased and the cells are hypochromic and microcytic. Polycythemic patients monitored with microhematocrits may be phlebotomized incorrectly because of this abnormality. We suggest the use of Coulter S hematocrits or spectrophotometric hemoglobin levels to monitor polycythemic patients.