If the table of maturation times is plotted with hematocrit as x-axis and the maturation time in days as the y-axis, a straight line can be generated with the following equation:
maturation factor =
= 3.25 - ((0.05) * (hematocrit))
If this equation is used, the equation for the RPI becomes
RPI =
= (reticulocyte count in percent) / 1% * ((hematocrit) / (146.25-(2.25 * (hematocrit))))
= ((reticulocyte count ) * (hematocrit)) / (146.25 - (2.25 * (hematocrit)))
where:
• The reticulocyte count and hematocrit represent numbers from 0 to 100, not decimal fractions.
• Division by 1% either allows the reticulocyte count to appear as a whole number, or it can be viewed as the normal reticulocyte count.
• 146.25 = 45 * 3.25; 2.25 = 45 * 0.05
The results of this equation are acceptable.
Alternatively, if a line is drawn through the mid-point of each "step", the following equation for correction factor is given:
maturation factor = 3.8006 - (0.06358 * (hematocrit))
and then the RPI =
= ((reticulocyte count) * (hematocrit)) / (171.027 - (2.8611 * (hematocrit)))
This equation gives results a little closer to the discrete factor equation.
Problem - handling newborns:
