Level of HbA, A2 and F are equally depressed leading on
to microcytic, hypochromic anemia. In the absence of
normal chains, b or γ chains increase and form HbH (b4)
Laboratory Diagnosis of b Thalassemia Minor
Hemoglobin is normal, MCV and MCH. MCHC is normal.
¾ Microcytic, hypochromic cells; target cells
¾ Basophilic stippling, reticulocytosis (up to 6%)
¾ Osmotic fragility is decreased.
¾ HbA2 increased, slight increase in HbF.
Laboratory Diagnosis of b Thalassemia Major
(Resembles iron deficiency anemia)
¾ Marked microcytosis with hypochromia
¾ Moderate degree of anisopoikilocytosis, teardrop cells
¾ All; MCV, MCH and MCHC are diminished
¾ Normoblasts (intermediate/late) in peripheral smear.
¾ Granular inclusions in cytoplasm, represent a-chain
aggregates which can be shown by methyl violet
¾ Polychromasia and moderate degree of punctate
¾ Leukocytosis (5,000–40,000) with shift to the left
¾ Platelet count normal but decreases with splenomegaly
¾ Osmotic fragility decreased, the curve has a tail because
¾ Evidences of intravascular hemolysis.
¾ Increase in early and intermediate normoblasts
¾ Methyl violet positive inclusion bodies and PAS positive
glycogen (PAS-periodic acid Schiff’s reagent)
¾ Sideroblastosis, often ring sideroblasts.
¾ HbF (10–98%) estimated also by acid elution and alkali
Laboratory Diagnosis of HbH Disease
¾ Marked microcytosis with hypochromia
¾ Target cells, fragmented cells and normoblasts in
¾ Reticulocytosis, basophilic stippling
Demonstration of HbH Inclusions
With a redox dye, e.g. brilliant cresyl blue (BCB) or new
methylene blue (NMB); HbH being relatively unstable,
precipitates and the red cells appear pitted with numerous
inclusions (golfball appearance).
At pH 8.6, both HbH and Hb Bart’s are fast moving, they
migrate in front of HbA towards anode.
¾ Marked anisopoikilocytosis with hypochromia
¾ Target cells and normoblasts.
Laboratory Diagnosis of Aplastic Anemia
¾ RBC morphology is usually normal (polychromasia,
normoblasts and stippling usually not seen)
¾ Sometimes macrocytosis, mild anisopoikilocytosis
¾ Hb and PCV are diminished to about 7 g% and 20%
¾ Red cell osmotic fragility is normal
¾ Leukopenia—neutropenia, polymorphs are qualitatively
and quantitatively abnormal, show coarse granules
• Absolute lymphocytopenia but relative lymphocytosis
• Neutrophil alkaline phosphatase count is increased
¾ Clot retraction time is increased
¾ Coagulation parameters are abnormal
¾ Radio-iron bone marrow uptake is reduced
¾ Red cell life may be decreased
¾ Plasma erythropoietin level is raised.
¾ Is hypoplastic (there is both myeloid and erythroid
¾ Plasma cells and reticulum cells are prominent
¾ Megakaryocytes are diminished in number
¾ WBCs may show maturation arrest
¾ Developing granulocytes are abnormal and may show:
¾ Bone marrow iron may be normal or increased.
Hence, the diagnosis is based upon:
¾ No immature cells in peripheral smear
¾ Bone marrow is aplastic/hypoplastic (if 2 consecutive
aspirations have been unsuccessful do a bone marrow
Classification and Causes of Aplastic Anemia
• Effects of chemical/physical agents on bone
• Familial hypoplastic anemia (Fanconi’s syndrome)
• Aplastic anemia associated with
– Infective hepatitis (1–2%) (usually post hepatitis A)
– Paroxysmal nocturnal hemoglobinuria (PNH).
• Congenital (Diamond Blackfan type)
– Without thymoma. (In both primary and secondary aplastic anemia clinical and hematological
– Primary type is less common.
Especially those which have an amino group near a
Bone marrow depression depends upon:
¾ Dosage and period of treatment
¾ Idiosyncrasy, susceptibility and hypersensitivity to the
Drugs which regularly cause aplastic anemia:
Drugs which occasionally cause bone marrow depression:
(Either because of idiosyncrasy or hypersensitivity)
• Colchicine. (Commonest drugs—phenyl and oxyphenylbutazone and chloramphenicol).
¾ Ionizing radiation is most dangerous (e.g. X-ray, γ rays,
¾ Particles have a limited range and hence cause effects
Reduction in number of the three blood cells types RBCs,
Platelet count < 1.5 lakh/cu mm.
¾ Subleukemic leukemia: Refractory anemia with
¾ Pancytopenia with hyperplastic bone marrow
¾ Bone marrow infiltration or replacement
¾ Megaloblastic macrocytic anemia
¾ Systemic lupus erythematosus
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