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Pathogenic Classification of Microcytic & Hypochromic Anemias
(I) DISORDERS OF IRON METABOLISM
1. iron-deficiency anemia
2. anemia of chronic disease
3. atransferrinemia
4. Shahidi-Nathan-Diamond syndrome
5. familial microcytic anemia with impaired absorption & metabolism of iron
6. Antibodies to the transferrin receptor
7. Gallium administration
8. aluminum intoxication
(II) Disorders of Globin Synthesis:
1. the thalassemias
2. hgb E trait & hgb E disease
3. hgb C disease
4. unstable hgb diseases
(III) Disorders of Porphyrin & Heme Synthesis:
(IV) Sideroblastic Anemias
1. defective ALA synthesis
1a. vitamin B6 deficiency
1b. defective vitamin B6 metabolism induced by drugs or toxins
1c. defective ALA synthase activity
(V) Deficiency of Corporphyrinogen Oxidase
(VI) Deficiency of Heme Synthesis
(VII) Lead Intoxication
(VIII) Unknown Causes
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Microcytosis Without Anemia:
Happens mostly in abnormal hemoglobin diseases. Heme synthesis is not impaired. Microcytosis, for example, can be detected in patients who are heterozygote for hemoglobin E gene. In these patients, anemia is not seen. Even in homozygotes, despite a greater degree of microcytosis, little or no anemia can be detected. ___________________________________________________________
Calculations used for Interpreting Erythrocyte Indices in Microcytic anemia
MCV-(Hb x 5)-RBC-3.4
Thalassemia Minor <0
Iron Deficiency >0
MCV/RBC
Thalassemia Minor <13
Iron Deficiency >13
MCH/RBC
Thalassemia Minor <3.8
Iron Deficiency >3.8
RBC
Thalassemia Minor >5.0
Iron Deficiency <5.0
MCH X (MCV)e2/100
Thalassemia Minor <1530
Iron Deficiency >1530
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