Page 315 - Textbook of Pathology, 6th Edition

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Figure 12.14 Iron deficiency anaemia. A, PBF showing microcytic hypochromic anaemia. There is moderate microcytosis and hypochromia. CHAPTER 12
B, Examination of bone marrow aspirate showing micronormoblastic erythropoiesis.

Laboratory Findings iii) Reticulocyte count. The reticulocyte count is normal
The development of anaemia progresses in 3 stages: or reduced but may be slightly raised (2-5%) in cases after
Firstly, storage iron depletion occurs during which iron haemorrhage.
reserves are lost without compromise of the iron supply iv) Absolute values. The red cell indices reveal a
for erythropoiesis. diminished MCV (below 50 fl), diminished MCH (below
The next stage is iron deficient erythropoiesis during 15 pg), and diminished MCHC (below 20 g/dl).
which the erythroid iron supply is reduced without the v) Leucocytes. The total and differential white cell counts
development of anaemia. are usually normal.
The final stage is the development of frank iron vi) Platelets. Platelet count is usually normal but may be
deficiency anaemia when the red cells become microcytic slightly to moderately raised in patients who have had
and hypochromic. recent bleeding.
The following laboratory tests can be used to assess the
varying degree of iron deficiency (Fig. 12.13): 2.BONE MARROW FINDINGS. Bone marrow exami-
1.BLOOD PICTURE AND RED CELL INDICES. The nation is not essential in such cases routinely but is done Introduction to Haematopoietic System and Disorders of Erythroid Series
degree of anaemia varies. It is usually mild to moderate in complicated cases so as to distinguish from other
but occasionally it may be marked (haemoglobin less than hypochromic anaemias. The usual findings are as follows
6 g/dl) due to persistent and severe blood loss. The salient (Fig.12.14,B):
haematological findings in these cases are as under. i) Marrow cellularity. The marrow cellularity is increased
i) Haemoglobin. The essential feature is a fall in due to erythroid hyperplasia (myeloid-erythroid ratio
haemoglobin concentration up to a variable degree. decreased).
ii) Red cells. The red cells in the blood film are hypo- ii)Erythropoiesis. There is normoblastic erythropoiesis
chromic and microcytic, and there is anisocytosis and with predominance of small polychromatic normoblasts
poikilocytosis (Fig. 12.14,A). Hypochromia generally (micronormoblasts). These normoblasts have a thin rim
precedes microcytosis. Hypochromia is due to poor filling of cytoplasm around the nucleus and a ragged and
of the red cells with haemoglobin so that there is increased irregular cell border. The cytoplasmic maturation lags behind
central pallor. In severe cases, there may be only a thin so that the late normoblasts have pyknotic nucleus but
rim of pink staining at the periphery. Target cells, elliptical persisting polychromatic cytoplasm (compared from
forms and polychromatic cells are often present. megaloblastic anaemia in which the nuclear maturation
Normoblasts are uncommon. RBC count is below normal lags behind, page 307).
but is generally not proportionate to the fall in
haemoglobin value. When iron deficiency is associated iii) Other cells. Myeloid, lymphoid and megakaryocytic
cells are normal in number and morphology.
with severe folate or vitamin B deficiency, a dimorphic
12
blood picture occurs with dual population of red cells— iv) Marrow iron. Iron staining (Prussian blue reaction)
macrocytic as well as microcytic hypochromic. carried out on bone marrow aspirate smear shows