Defense Date


Document Type


Degree Name

Master of Science


Health Related Sciences

First Advisor

Joanne Stephens


Secondary polycythemia is defined as an absolute erythrocytosis caused by an enhanced stimulation of red blood cell production. One of the most common methods of monitoring the degree of polycythemia is the measurement of the hematocrit. The hematocrit is the measurement of the volume of red blood cells.expressed as a percentage of the volume of whole blood in a sample. This measurement is usually done using one of two methods: (1) the Coulter Model S® or (2) the centrifuged micro-hematocrit method. However, we have noted a significant difference in the hematocrit values determined by these two methods when the hematocrits exceed 54 percent. As many as 10 hematocrit units of difference have been reported (1 hematocrit unit = ml of packed erythrocytes/100 ml of whole blood).

Several questions arise: (1) does this variation in hematocrit (hct) values increase in proportion to the increase in hematocrit; (2) is there a relationship between the fibrinogen level and the amount of trapped plasma in the centrifuged micro-hct; (3) is there a relationship between the red blood cell count (RBC), mean corpuscular volume (MCV), and whole blood viscosity; (4) which measurement is a better indicator of the degree of polycythemia and the increase in viscosity.

To answer these questions data from the Coulter Model S®: centrifuged micro-hct, whole blood viscosity and fibrinogen determination were evaluated. With these data it was planned to determine if it would be possible (1) to construct a nomogram establishing the relationship between the micro-hat and Coulter S® hct greater than 50 percent for the conversion of one value to the other, and (2) to assess the degree of polycythemia and the need for phlebotomy by the use of each measurement.


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