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82 / Chapter 6 Haemolytic anaemias

are defects of other systems (e.g. a myopathy). Th e Hereditary d isorders of h aemoglobin
most frequently encountered is pyruvate kinase s ynthesis
defi ciency.
Several of these cause clinical haemolysis. Th ey are
discussed in Chapter 7 .
Pyruvate k inase d efi ciency

This is inherited as an autosomal recessive, the Acquired h aemolytic a naemias

affected patients being homozygous or doubly het-

erozygous. Over 100 different mutations have been Immune h aemolytic a naemias
described. The red cells become rigid as a result of

reduced adenosine triphosphate (ATP) formation. Autoimmune h aemolytic a naemias

The severity of the anaemia varies widely (haemo-
Autoimmune haemolytic anaemias (AIHAs) are
globin 4 – 10 g/dL) and causes relatively mild symp-
caused by antibody production by the body against
toms because of a shift to the right in the oxygen
its own red cells. They are characterized by a positive

(O 2 ) dissociation curve caused by a rise in intracel-
direct antiglobulin test (DAT) also known as the
lular 2,3 - diphosphoglycerate (2,3 - DPG). Clinically,
Coombs ’ test (see Fig. 29.5 ) and divided into ‘ warm ’
jaundice is usual and gallstones frequent. Frontal
and cold ’ types (Table 6.5 ) according to whether
‘

bossing may be present. The blood fi lm shows
the antibody reacts more strongly with red cells at
poikilocytosis and distorted ‘ prickle ’ cells, particu-
37 ° C or 4 ° C.
larly post - splenectomy. Direct enzyme assay is
needed to make the diagnosis. Splenectomy may
alleviate the anaemia but does not cure it and is Warm a utoimmune h aemolytic a naemias

indicated in those patients who need frequent Th e red cells are coated with immunoglobulin (Ig),
transfusions. usually immunoglobulin G (IgG) alone or with

Table 6.5 Immune haemolytic anaemias: classifi cation.
Warm type Cold type
Autoimmune
Idiopathic Idiopathic
Secondary Secondary
SLE, other ‘ autoimmune ’ diseases Infections – Mycoplasma pneumonia, infectious mononucleosis
CLL, lymphomas Lymphoma
Drugs (e.g. methyldopa) Paroxysmal cold haemoglobinuria (rare, sometimes associated
with infections, e.g. syphilis)
Alloimmune
Induced by red cell antigens
Haemolytic transfusion reactions
Haemolytic disease of the newborn
Post stem cell grafts
Drug induced
Drug – red cell membrane complex
Immune complex

CLL, chronic lymphocytic leukaemia; SLE, systemic lupus erythematosus.