Figure 1
From: Blood glucose measurements in the critically ill: more than just a blood draw
Glucose concentration: water content expressed as percent volume. With a hematocrit of 0.4 and a water content for the fraction 'Cells' of approximately 70%, the total water content will be 28% of total volume (whole blood). From the 60% plasma volume, 90% will be water, thus giving a water content of 54% for the plasma portion of whole blood. The total water content of whole blood then is 82% (54% + 28%). For a hematocrit of 0.4 the plasma/whole blood ratio of water content is 0.9/0.82 = 1.10, which reflects the 10% higher glucose values in plasma compared to whole blood.