A little background, to make this a "full service" reply....
The reticulocyte count is frequently reported as number of reticulocytes
within a given number of rbc's. The problem with the raw percentage data is
that, in states such as anemia, it does not correctly indicate the
relationship between the peripheral red cell population and reticulocyte
production. Thus, when you evaluate an anemic patient's retic count based on
"normal ranges", this patient should not be within this range, as their BM
should be compensating for the decreased rbc mass.
An improved method for reporting these values is the corrected reticulocyte
count, which makes adjustments based on the severity of the patient's
anemia. It is calculated as:
Patient's hematocrit
--------------------- X retic count = corrected retic count
0.45 L/L
where 0.45 represents a "normal" hematocrit.
This is better, but still not optimal.
If polychromatophilic rbc's are noted on the peripheral smear, these
represents reticulocytes that must undergo additional maturation in the
periphery before they are fully functional. These "stress" retics are
released in many anemic states, with their number correlating to the
severity of the anemia. So in stimulated marrow, hematocrits of 0.35, .25,
and .15 are associated with early retic release and prolongation of retic
maturation in the periphery by 1.5, 2.0, and 2.5 days respectively.
Correction for this additional maturation time is referred to as the
reticulocyte production index (RPI). I believe RMI is an analogous term. It
is calculated as:
Patient's hematocrit 1
--------------------- X retic count X _________________
0.45 L/L maturation time of
stress retics based
on hematocrit
In general, an RPI>2 indicates an appropriate BM response whereas an RPI<2
indicates inadequate compensation.
Here are a couple of references:
Friedman, E.W.: Diagnostic Medicine, 7(6): 29, 1984
Hillman, R.S.: Journal of Clinical Investigation, 48:443, 1969
Hope this helps someone.
kb
--
-----------------------------------------------
Keith Bahjat
Graduate Assistant
University of Florida
College of Medicine
Gainesville, Florida
kbahjat@ufl.edu
> From: Dagna Sheerar <dagnas@primate.wisc.edu>
> Date: Thu, 11 Nov 1999 12:16:57 -0600
> To: Cytometry Mailing List <cytometry@flowcyt.cyto.purdue.edu>
> Subject: Reticulocyte Maturity Index
>
>
> Hello Flowers:
>
> We are looking into the possibility of enumerating reticulocytes on our
> FACSCalibur. We have determined that we can use ReticONE (a Reagent kit
> offered by Beckman Coulter). We are now looking for a calculation to
> determine the Reticulocyte Maturity Index. If anyone could direct me to
> specific research in the literature, or has experience with this number and
> would like to share, I would be very grateful.
>
> Thank you very much,
>
> Dagna
>
> Dagna Sheerar
> Wisconsin Regional Primate Research Center
> 1220 Capitol Court
> Building #2 Room 215
> Madison, WI 53715
> 608 265 3796
> dagnas@primate.wisc.edu
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