Diagnosis of b-Thalassemia
Laboratory diagnosis:
Hematological findings:
No anemia is present at
birth, but the hemoglobin level decreases progressively during the first months
of life, in the range of 2-3 gm / dl or even lower. The appearance of blood
film varies to some what depending on whether the spleen is intact or not. In
nonsplenectomized patients, large poikilocytes are common whereas after
splenctomy, large flat macrocytes and small deformed microcytes are frequently
seen (Honig, 2000).
A reticulocytic count
although elevated (5-15 %) is lower than would be expected from the degree of
anemia if marrow function is normal. This disparity is explained by ineffective
erythropoiesis (Edward et al., 1990).
Both platelet count and
leucocytic count in patients with ß- thalassemia major are usually increased
reflecting an accelerated rate of hematopoiesis. Platelet count in excess of 1
million and white cell count in the range of 15 to 22 thousands are common
after splenectomy (Mc Donagh and Nienhuis, 1993).
Biochemical changes:
The serum is icteric with
elevated unconjugated bilirubin ranging between 2.0 to 4.0 mg /dl. Liver
function tests are frequently increased due to hepatic damage secondary to
hemosiderosis. Serum iron and ferritin are increased (Clark
et al., 2000).
Serum zinc, serum and
leucocytic ascorbic acid, vitamin E and folic acid are low. LDL is elevated as
consequence of ineffective erythropoiesis (Beutler et al., 2003).
Hb Electrophoriesis:
Hb electrophoresis usually
reveals an elevated HbF fraction, which tends to decrease with the age but is
always higher than normal, ranging from 10 to 90 %, distributed heterogeneously
in the RBCs. HbA2: HbA ratio, which is normally 1:40 is increased to less than
1:20 in thalassemia major (Schwartz et al., 1995).
Bone Marrow Changes:
The bone marrow is
remarkably hypercelluar with profound normoblastic hyperplasia. Deficient
hemoglobin content of red cell precursors as well as cytoplasm inclusions is
apparent. Macrophages similar in apperance to pseudogaucher cells may be
present due to increased catabolism of erythrocytes (Alter, 2003).
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