Hypersplenism is associated with enlargement
of the spleen.
A common physical sign, enlargement of the spleen may have many causes.
Irrespective of the cause, enlargement may result in development of
hypersplenism.
This syndrome is associated with two main problems:
sequestration of red cells, white cells and platelets, and premature destruction
of red cells.
Hypersplenism therefore leads to reduction in the levels of red cells, white
cells and
platelets in the blood (pancytopenia) and, as a compensatory response,
hyperplasia
of the bone marrow. Splenectomy leads to clinical and haematological
improvement.
Another important complication of an enlarged spleen is that it is vulnerable to
traumatic rupture, e.g. in glandular fever or malaria.
Hyposplenism increases the risk of serious bacterial infection by capsulated
organisms
Lack of splenic function is clinically encountered in three main circumstances:
surgical removal (for disease or trauma), sickle-cell disease (microvascular
occlusion
causes ischaemic atrophy, known as 'autosplenectomy'), and coeliac disease (splenic
atrophy).
As a consequence, patients become susceptible to recurrent bacterial infections,
particularly by capsulated bacteria (Streptococcus pneumoniae, Haemophilus
influenzae,
Neisseria meningitidis, Escherichia coli), and develop severe septicaemia,
intravascular
coagulation, and multi-organ failure.
There are also abnormalities of red cells, which develop inclusion bodies
(Howell-Jolly bodies)
and abnormal shape (schistocytes and target cells).
Usually, abnormal red cells are removed from the spleen as they squeeze through
the splenic sinusoids. |
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