d. The following section details the investigations used to help diagnose an
immune etiology for a hemolytic anemia, but the techniques employed can be used for
the investigation of any positive direct antiglobulin test. The specific investigations for
"in vivo" sensitization associated with incompatible blood transfusions and hemolytic
disease of the newborn are dealt with in Lesson 2, Section II and Lesson 3, SectIon Il.
2-2.
IMMUNE HEMOLYTIC ANEMIA
a. Immune hemolytic anemia is a state in which a patient has a shortened RBC
survival associated with hemolysis resulting from an immune reaction. There are many
causes for anemia, one of which is hemolysis. Furthermore, there are many causes for
hemolytic anemia, and one involves an immune mechanism. The serologic
investigations carried out in the blood bank do not determine whether a patient has
hemolytic anemia; this is decided by the clinical findings and laboratory data such as
hemoglobin, hematocrit, reticulocyte count, RBC morphology, bilirubin, haptoglobins,
LDH, and possibly isotope studies. The serologic results do help decide if the
hemolysis has an immune basis, and if it does, what type of immune hemolytic anemia
is present? This is important since the treatment for each type is very different.
b. Immune hemolytic anemia may be classified in various ways. Common
classifications based on serologic findings are as follows:
(1)
Autoimmune hemolvtic anemia (AIHA).
(a) AIHA associated with warm antibodies.
1 Primary (idiopathic).
2 Secondary (lymphoma, SLE, Infections, carcinoma, and so
forth).
(b) AIHA associated with cold antibodies.
1 Cold agglutinin syndrome.
a Primary (idiopathic).
b Secondary (lymphoma, mycoplasma pneumonia, infectious
mononucleosis).
2 Paroxysmal cold hemoglobinuria.
a Primary (idiopathic).
b Secondary (syphilis, viral infections).
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