MLAB 1415: Hematology
Keri Brophy-Martinez
Thalassemia
Part Two: Alpha Thalassemia
Alpha Thalassemia
Predominant cause of alpha thalassemias is large
number of gene deletions in the alpha-globin
gene.
 Four types in alpha thalassemia:

◦
◦
◦
◦
Silent Carrier State
Alpha Thalassemia Trait (Alpha Thalassemia Minor)
Hemoglobin H Disease
Bart's Hydrops Fetalis Syndrome
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Hemoglobin H Disease



Second most severe form alpha thalassemia.
Only one alpha gene out of four is functional
Results in accumulation of excess unpaired
gamma or beta chains.
◦ The excess chains pair up to form tetrads
 Beta: hemoglobin H (adults)
 Gamma: hemoglobin Bart’s (infants)



Unstable
Precipitates within RBCs triggers hemolysis
High affinity for oxygen which reduces oxygen
delivery to the tissues
3
Laboratory Findings:
Hemoglobin H Disease

RBCs are microcytic, hypochromic with marked
poikilocytosis. Numerous target cells.
4
Bart’s Hydrops Fetalis Syndrome or αThalassemia major




Have no functioning alpha chain genes
Baby born with Hydrops Fetalis, which is edema and
ascites caused by accumulation of serous fluid in fetal
tissues as result of severe anemia.
Hepatosplenomegaly and cardiomegaly are present
Pregnancies dangerous to mother. Increased risk of
toxemia and severe postpartum hemorrhage.
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Bart’s Hydrops Fetalis Syndrome

Predominant hemoglobin is Hemoglobin Bart,
along with Hemoglobin Portland and traces of
Hemoglobin H.
Hemoglobin Bart's has high oxygen affinity so
cannot carry oxygen to tissues.
 Fetus dies in utero or shortly after birth.

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Laboratory
Diagnosis of
Thalassemia
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Laboratory Diagnosis of Thalassemia

Need to start with patient's individual history and family
history. Ethnic background important.

Perform physical examination:
◦ Pallor indicating anemia.
◦ Jaundice indicating hemolysis.
◦ Splenomegaly due to pooling of abnormal cells.
◦ Skeletal deformity, especially in beta thalassemia major.
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CBC with Differential

Decreased
◦ Hemoglobin, hematocrit
◦ Mean corpuscular volume (MCV)
◦ Mean corpuscular hemoglobin (MCH)
◦ Normal to slightly decreased Mean Corpuscular Hemoglobin Concentration
(MCHC)

Have normal or elevated RBC count with a normal red cell volume distribution (RDW).
◦ Elevated RBC count with markedly decreased MCV differentiates thalassemia from
iron deficiency anemia

Differential
◦ Microcytic, hypochromic RBCs (except in carrier states)
◦ Mild to moderate poikilocytosis
◦ In more severe cases, see marked number of target cells and
elliptocytes,polychromasia, basophilic stippling, and NRBCs.
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Other Hematology Tests

Reticulocyte Count
◦ Usually elevated. Degree of elevation depends upon
severity of thalassemia.

Osmotic Fragility
◦ Have decreased osmotic fragility.
◦ Is not very useful fact for diagnosing thalassemia. Is
an inexpensive way of screening for carrier states.
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Brilliant Cresyl Blue Stain



Incubation with brilliant cresyl
blue stain causes Hemoglobin
H to precipitate.
Results in characteristic
appearance of multiple discrete
inclusions -golf ball appearance
of RBCs.
Inclusions smaller than Heinz
bodies and are evenly
distributed throughout cell.
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Acid Elution Stain




Based on Kleihauer-Betke
procedure.
Acid pH will dissolve Hemoglobin A
from red cells.
Hemoglobin F is resistant to
denaturation and remains in
cell. Stain slide with eosin.
Normal adult cells appear as "ghost"
cells while cells with Hb F stain
varying shades of pink.
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Hemoglobin Electrophoresis
Important role in diagnosing and differentiating
various forms of thalassemias.
 Can differentiate among Hb A, Hb A2, and Hb F, as
well as detect presence of abnormal hemoglobins
such as Hemoglobin Lepore, hemoglobin Bart's,
or Hemoglobin Constant Spring.
 Also aids in detecting combinations of
thalassemia and hemoglobinopathies.

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Hemoglobin Quantitation
Elevation of Hb A2 excellent way to detect
heterozygote carrier of beta
thalassemia. Variations in gene expression
in thalassemias results in different amounts
of Hb A2 being produced.
 Can also quantitate levels of Hb F.

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Routine Chemistry Tests
Indirect bilirubin elevated in thalassemia
major and intermedia.
 Assessment of iron status, total iron
binding capacity, and ferritin level important
in differentiating thalassemia from iron
deficiency anemia.

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Differential Diagnosis of Microcytic,
Hypochromic Anemias
RDW
Serum Iron
TIBC
Serum
Ferritin
Inc
Dec
Inc
Dec
Alpha Thal
Norm
Norm
Norm
Norm
Beta Thal
Norm
Norm
Norm
Norm
Hgb E Disease
Norm
Norm
Norm
Norm
Anemia of
Chronic
Inflammation
Norm
Dec
Dec
Inc
Sideroblastic
Anemia
Inc
Inc
Norm
Inc
Norm
Norm
Norm
Norm
Iron Deficiency
Lead Poisoning
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References
Harmening, D. M. (2009). Clinical Hematology and
Fundamentals of Hemostasis. Philadelphia: F.A Davis.
• McKenzie, S. B., & Williams, J. L. (2010). Clinical Laboratory
Hematology . Upper Saddle River: Pearson Education,
Inc.
• http://prepgmedicos.redstetho.com/forum/viewtopic.ph
p?f=88&t=5166&start=0
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