AUTOAGGLUTINATION
In
severe cases of immune mediated
hemolytic anemia, the immune
destruction of red cells is so
blatant that the red cells
clump together (because
their antibody coatings stick
together) when a drop of blood is
placed on a microscope slide.
Imagine a drop of blood forming not
a red spot but a yellow spot with a
small red clump inside it. This
finding is especially for boding
.
LEUKEMOID REACTION
Classically, in IMHA the stimulation
of the bone marrow is so strong that
even the white blood cells lines
(which have very little to do with
this disease but which also are born
and incubate in the bone marrow
along side the red blood cells) are
stimulated. This leads to
white blood cell counts that are
spectacularly high.
MORE
TESTS NEEDED ?
COOMB'S TEST (ALSO CALLED A "DIRECT
ANTIBODY TEST")
This is a test designed
to identify antibodies coating red blood
cell surfaces. This test is the current
state of the art for the diagnosis of
IMHA but, unfortunately, it is not as
helpful as it might seem. It can be
erroneously positive in the presence of
inflammation or infectious disease
(which might lead to harmless attachment
of antibody to red cell surfaces) or in
the event of prior blood transfusion
(ultimately transfused red cells are
removed from the immune system).
The Coomb's test can be erroneously
negative for a number of reasons
as well. If the clinical picture
fits with IMHA, often the Coomb's test
is skipped.