7 Dimorphic Population

Michelle To and Valentin Villatoro

Images show peripheral blood smears containing a dimorphic population (hypochromic-microcytic, and normochromic-normocytic red blood cells). From MLS Collection, University of Alberta.

Image 1: 100x oil immersion. https://doi.org/10.7939/R3T14V447

Image 2: 50x oil immersion. https://doi.org/10.7939/R3V11W18D


Cell Description:

The peripheral blood smear shows that there are two distinct red blood cell populations present. The different red blood cell populations that may be seen are normocytic/normochromic, microcytic/hypochromic, macrocytic/normochromic.1,2


Cell Formation:

The cause for the formation of a dimorphic red blood cell population varies depending on the clinical condition.


Associated Disease/Clinical States:1-2

Sideroblastic Anemia

Myelodysplastic Syndrome (MDS)

Iron, Vitamin B12, Folate deficiency (and during the early treatment stage)


Erythropoietin Therapy


Note: RDW > 14.5%3


1. Ford J. Red blood cell morphology. Int J Lab Hematol [Internet]. 2013 Mar 9 [cited 2018 Jul 12];35(3):351–7. Available from: https://doi.org/10.1111/ijlh.12082

2. Constantino BT. The red cell histogram and the dimorphic red cell population. Lab Med [Internet]. 2011 May 1 [cited 2018 Jul 23];42(5):300–8. Available from: http://dx.doi.org/10.1309/LMF1UY85HEKBMIWO

3. Rodak BF, Carr JH. Variations in size and color of erythrocytes. In: Clinical hematology atlas. 5th ed. St. Louis, Missouri: Elsevier Inc.; 2017. p. 89-92.


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Dimorphic Population Copyright © 2019 by Michelle To and Valentin Villatoro is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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