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Immune Mediated Haemolytic Anaemia (view source)
Revision as of 16:39, 17 August 2010
, 16:39, 17 August 2010no edit summary
| Also known as:
| Also known as:
| '''IMHA'''<br>
| '''IMHA'''<br>
'''Autoimmune haemolytic anaemia (AIHA)'''
'''Autoimmune haemolytic anaemia (AIHA)'''<br>
'''Pure red cell aplasia (PRCA)'''
|}
|}
IMHA may occur as a '''primary''' disease with no apparent cause or it may be '''secondary''' to another systemic insult. Possible secondary causes of IMHA include bacterial and parasite infections (including ''[[Babesia canis]]'' in dogs and ''[[Mycoplasma haemofelis]]'' in cats), adverse drug reactions, neoplasia (especially myeloproliferative and lymphoproliferative disease) and live vaccines, although the association between vaccination and immune-mediated disease remains controversial.
IMHA may occur as a '''primary''' disease with no apparent cause or it may be '''secondary''' to another systemic insult. Possible secondary causes of IMHA include bacterial and parasite infections (including ''[[Babesia canis]]'' in dogs and ''[[Mycoplasma haemofelis]]'' in cats), adverse drug reactions, neoplasia (especially myeloproliferative and lymphoproliferative disease) and live vaccines, although the association between vaccination and immune-mediated disease remains controversial.
The majority of cases of IMHA affect only the circulating red blood cells resulting in a strongly regenerative anaemia as the bone marrow stem cells respond to the disease. In a small number of cases, antibodies are produced that affect the stem cells of the erythroid lineage in the bone marrow, resulting in a non-regenerative anaemia that still bears many of the same clinical features as IMHA. Although the two diseases have been considered separately in the past, they really represent two ends of a spectrum of immune-mediated disease directed at cells of the erythroid line.
The widespread lysis of red blood cells causes disease in the following ways:
The widespread lysis of red blood cells causes disease in the following ways:
A '''Coomb's test''' can be used to diagnose cases of IMHA that are caused by incomplete antibodies. The red blood cells from a patient are mixed with Coomb's antiserum (IgG antiobies directed against IgG) and, in cases where the patient has IMHA with antibodies attached to the surface of the erythrocytes, the antiserum will result in the formation of aggregates of cells. The titre of the test should be evaluated as weakly positive results may occur with other diseases.
A '''Coomb's test''' can be used to diagnose cases of IMHA that are caused by incomplete antibodies. The red blood cells from a patient are mixed with Coomb's antiserum (IgG antiobies directed against IgG) and, in cases where the patient has IMHA with antibodies attached to the surface of the erythrocytes, the antiserum will result in the formation of aggregates of cells. The titre of the test should be evaluated as weakly positive results may occur with other diseases.
In cases of pure red cell aplasia, a Coomb's test may still be positive but, experimentally, a definitive diagnosis can only be made by transfusing the serum of one animal to another and documenting the development of anaemia in the recipient.
===Diagnostic Imaging===
===Diagnostic Imaging===