Classification Of The Anaemias

The aim of this series of case studies is to teach the principles of diagnosis of the important anaemias using medical history, haematological data and peripheral blood film morphology. The anaemias are broadly classified into the following areas:

1. Iron deficiency anaemia
   The blood film exhibits hypochromic, microcytic red blood cells. Confirmation of diagnosis is made by performing a serum iron estimation and assessing body iron stores. The cause of deficiency must then be determined. Platelet levels are also often raised in association with haemorrhagic iron deficiency.


2. Megaloblastic anaemia
   The blood film often shows macrocytes, poikilocytes and cell fragments. The MCV is usually raised. Diagnosis can be confirmed by the measurement of vitamin B12 and folate in the serum. The red cell count is also often low.


3. Haemolytic anaemia
   The haemolytic anaemias are characterised by a reduced red cell life span. This is due to a number of factors such as changes in red cell membrane permeability, fragmentation and phagocytosis of the red cells. Diagnosis is more complex, however the majority of cases exhibit a low Hb and evidence of excessive cell breakdown often revealed by a raised reticulocyte level. Features commonly shown in the blood film are polychromasia and varieties of irregularly shaped cells including spherocytes, schistocytes, target and sickle cells.


4. Aplastic anaemia
   This involves a failure of the bone marrow to produce red blood cells, and sometimes white cells and platelets are also affected. All aspects of the peripheral blood features may be lowered. The MCH and MCHC are generally normal, although the MCV is commonly raised.