Page 89 - Essential Haematology

Chapter 6 Haemolytic anaemias / 75

Introduction to h aemolytic Classifi cation
a naemias Table 6.1 is a simplifi ed classification of the haemo-

lytic anaemias. Hereditary haemolytic anaemias are
Haemolytic anaemias are defi ned as those anaemias
the result of ‘ intrinsic ’ red cell defects whereas
that result from an increase in the rate of red cell
acquired haemolytic anaemias are usually the result
destruction. Because of erythropoietic hyperplasia
of an ‘ extracorpuscular ’ or ‘ environmental ’ change.
and anatomical extension of bone marrow, red cell
Paroxysmal nocturnal haemoglobinuria (PNH) is
destruction may be increased several - fold before the
the exception because although it is an acquired
patient becomes anaemic – compensated haemo-
disorder, the PNH red cells have an intrinsic defect.

lytic disease. The normal adult marrow, after full
expansion, is able to produce red cells at 6 – 8 times
‘

the normal rate provided this is effective ’ . Th erefore,
Clinical f eatures
haemolytic anaemia may not be seen until the red
cell lifespan is less than 30 days. It leads to a marked Th e patient may show pallor of the mucous mem-
reticulocytosis, particularly in the more anaemic branes, mild fl uctuating jaundice and splenomegaly.
cases. There is no bilirubin in urine but this may turn dark

Table 6.1 Classifi cation of haemolytic anaemias.

Hereditary Acquired

Membrane Immune
Hereditary spherocytosis, hereditary elliptocytosis Autoimmune
Warm antibody type
Metabolism
Cold antibody type
G6PD defi ciency, pyruvate kinase defi ciency
Alloimmune
Haemoglobin
Haemolytic transfusion reactions
Genetic abnormalities (Hb S, Hb C, unstable); see
Haemolytic disease of the newborn
Chapter 7
Allografts, especially stem cell transplantation
Drug associated
Red cell fragmentation syndromes
See Table 6.6
March haemoglobinuria
Infections
Malaria, clostridia
Chemical and physical agents
Especially drugs, industrial/domestic substances,
burns
Secondary
Liver and renal disease
Paroxysmal nocturnal haemoglobinuria

G6PD, glucose - 6 - phosphate dehydrogenase; Hb, haemoglobin.