Drug-induced hemolvtic anemia.
Alloimmune hemolytic anemia.
(a) Hemolytic disease of the newborn.
(b) Hemolytic transfusion reactions.
This Section will not deal with the alloimmune hemolytic anemias. See
Lesson 2, Section II and Lesson 3, Section II.
c. In one series of 200 patients with immune hemolytic anemia, 66 percent had
AIHA associated with warm antibodies, 16 percent had cold agglutinin syndrome, 2
percent had paroxysmal nocturnal hemoglobinuria, and in 16 percent the anemia was
drug-induced. Other reported series are similar.
GENERAL SEROLOGIC INVESTIGATIONS
Before any serologic tests are performed, it is important to collect blood samples
for the investigations in an appropriate manner.
a. Collection of Blood Sample. Collect clotted blood to provide serum and
blood in EDTA, to provide RBCS for the direct antiglobulin test, grouping, and
preparation of eluates. If it is not known whether the patient has AIHA associated with
warm or cold antibodies, it is preferable to collect blood and separate it at 37C. If
powerful cold autoantibodies are present, several problems can arise if the blood is not
kept at 37C.
Autoagglutination of RBCS will occur leading to difficulties in grouping.
(2) There will be a loss of antibody from the serum by auto-absorption,
leading to false low cold agglutinin titers, and so forth.
(3) "In vitro" complement autosensitization may occur if EDTA blood is not
used, leading to false increase in the strength of the direct antiglobulin test. EDTA will
prevent any "in vitro" complement sensitization, even if the blood is cooled; thus, any
complement detected on the RBCS represents "in vivo" sensitization.
(4) Possible hemolysis of the RBCS may occur "in vitro" utilizing antibody
and complement, again leading to false low laboratory values and possible
misinterpretation of "in vitro" hemoglobinemia, as being an "in vivo" occurrence.