Haemolytic Anaemias

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Brief description and classifications

  • definition of Anaemia

Anaemia is an altered physiological state characterised by a reduction in circulating haemoglobin. Haemoglobin is the oxygen carrying molecule found (only)in red blood cells.therefore, anaemia is attributed to a reduced circulating red cell mass; although, this term is invariably a misnomer as we shall see latter.

why haemoglobin? In clinical set ups, red cell mass is not routinely measured. It is a laborious, invasive and expensive activity. Haemoglobin measurements are conversely done to overcome all these negative atributes of red cell mass measurements.HAEMOGLOBIN IS THEREFORE THE BASIS OF MEASUREMENT AND NOMECLATURE FOR ANAEMIC STATES. THE UNITS OF MEASREMENTS ARE g/dl(g/L are now being used. It is the ICSH recommended unit of measurement.


Haemolytic anaemias can be classified using two ways as either;

  1. intra-corpuscular or extra-corpuscular Link titleor
  2. based on the rbc component responsible for the haemolysis;

(This classification has subclasses as bulleted below.)

  • membranopathies

these disorders are usually inherited. the r.b.c membrane loses some of the qualities that enable it to navigate the splenic bed therefore resulting in haemolysis. examples are. congenital spherocytosis, congenital ovalocytosis, congenital elliptocytosis.

  • enzymopathies

the rbc enzymes responsible for anaerobic glycolysis may get defective therefore exposing the rbc to possible oxidative haemolysis

  • haemoglobinopathies

these are disorders of the haemoglobin molecule. they are usually inherited mutations of Hb A. the resultant haemoglobin has altered physiochemical and physical properties that render the red cell to haemolysis.