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Steroids are the initial treatment for DBA patients following diagnosis
of DBA. Patients usually are started on prednisone at doses from
2-4 mg/kg/day and then slowly weaned to the lowest dose at which
the hemoglobin concentration is stable. Initially, 81% of patients
respond to steroids. An acceptable dose of prednisone for the long
term should be .5 mg/kg/day or less. The function of steroids in
maintaining acceptable hemoglobin is still unclear. DBA patients
may be particularly sensitive to corticosteroids even at low doses.Steroids
can have many potential side effects, especially at high doses.
These include weight gain, water/salt retention, hypertension, muscle
weakness, osteoporosis, impaired wound healing, headaches, suppression
of growth, cataracts, glaucoma, and endocrine abnormalities. Every
other day dosing, at low doses, can alleviate many of these side
effects.
When steroids are either ineffective or toxic, transfusion therapy
is the mainstay of treatment. Filtered packed red blood cell transfusions
are recommended to reduce transfusion reactions. Usually patients
require transfusions at 3 to 6 week intervals. The major complication
of transfusion therapy is iron overload. Liver biopsy or testing
with use of a SQUID machine (limited availability) provides the
most accurate measurement of iron stores. Deposition of iron in
major organs can lead to diabetes, heart and liver dysfunction,
and growth failure as well as other endocrine problems. Chelation
of iron with desferrioxamine (Desferal) subcutaneously should be
considered as soon as iron stores are found to be elevated. Easier
and less time consuming modes of administering chelation are currently
being researched.
Bone marrow transplantation (BMT) has been attempted with limited
success in only a small number of DBA patients. Bone marrow transplant
is still considered experimental and should be pursued cautiously.
Stem cell transplantation for DBA patients with HLA matched siblings
continues to be a viable option. According to the North American
Diamond Blackfan Anemia Registry (DBAR), there were 20 stem cell
transplants for DBA reported in the U.S. from 1993 through 1999.
Fifteen were from bone marrow and five from cord blood. Of the twenty,
eight were from HLA matched siblings. Of these eight, seven survived.
Two transplants involved family donors that did not have a complete
HLA match with the DBA patient. Both of these patients died. The
remaining ten transplants were from unrelated persons that had an
HLA match with the DBA patient. Of these ten, three survived. Given
these results, it is not surprising that most doctors do not recommend
stem cell transplantation unless the donor is a full HLA matched
sibling. Statistics from the North American Diamond Blackfan Anemia
Registry (DBAR) indicate the overall survival rate following BMT
is 59%. The statistics from the DBAR differ slightly from the statistics
gathered from the approximately 35 DBA transplants that have been
reported in the literature. Some of these 35 cases have been reported
more than once. Of the cases in the literature, most of the donors
were siblings; one was a mother, and one was a matched unrelated
donor. Ten of these have died. From these thirty-five reported cases,
the absolute cure rate is 71%, and the projected survival rate from
Kaplan-Meier analysis is 66%.
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