Reticulocyte count next to CBC is the first step in the work up of any anemias. What is reticulocyte?
Young RBC. In 24 hrs, a reticulocyte will become a mature RBC with a biconcave disk.
If you have an anemia, the reticulocyte count is imp b/c it tells you where the problem is: is the prob
in the BM in making the RBC, or is it a prob outside the BM causing the problem? To determine this,
look at reticulocyte ct. If the BM was the prob, then the reticulocyte ct would not have an
appropriate response. What is an appropriate response? You would have a BM with hyperplasia,
that has rev’d itself up, and making RBC’s and should be putting reticulocytes out prematurely,
therefore working correctly to correct the anemia. Therefore, it tells whether the BM is responding
appropriately or not. If you have blood loss right now, do not expect reticulocyte ct to be elevated
in 24 hrs; it takes at least 5-7 days to get the response of making more reticulocytes (like the kidney
making bicarb, which takes a few days (3-4) to make). If nothing is wrong with the BM, then it
should host a normal reticulocyte response; if there is something wrong, will not have a normal
response (imp b/c might decide whether you have to do a BM exam or not). Therefore, if you have a
normal reticulocyte ct, do not do a BM exam.
Have to correct the reticulocyte count for the degree of anemia.
Corrected reticulocyte ct = Hct of the pt ÷ 45 × reticulocyte ct that you are given
Example: pt’s Hct is 15% (which is very severe anemia), and the reticulocyte ct that was initially
measured is 9% (which is increased – anything over 3% is increased).
This ‘looks’ like the BM is responding correctly b/c the ret ct is 9% (but have to correct for the
degree of anemia). 15/45 X 9 is 3; so, when we correct for the anemia, we have 3%; that’s what the
corrected is – therefore, 3% or greater = good response; 3% or less = bad response; so, this figure is
saying that it is a reasonable response occurring in the pt.
Slide of a reticulocyte (know what it looks like) – need to do a special giemsa stain to see the black
filaments (which are RNA filaments); b/c they are RNA filaments, the reticulocyte is still synthesizing
Hb. So, in about 24 hrs, 25% the normal Hb is being synthesized and need RNA filaments; cannot
see these without doing a sp