MEGALOBLASTIC ANEMIA (Vitamin B12 & Folate deficiency)

• Megaloblastic anemia are associated with macrocytic & megaloblastic marrow erythropoiesis.
• 2 types of etiology-

1. Nutritional deficiency of vitamin B12 or folate
2. Deficiency of intrinsic factor

• Megaloblastic anemia are disorder caused by impaired DNA synthesis.
• Red cells formed from megaloblast are abnormal in shape and size, the most prominent abnormality being macrocytosis (macro- ovacytosis).
• Vitamin B12 and folic acid required for DNA synthesis hence nuclear maturation.

Vitamin B12 & folate metabolism-

Sources-

• Only dietary sources for Vitamin B12 are animal protein.
• Folate deficiency sources are fruits & vegetables.

Vitamin B12 absorption-

 Tissue stores-

• Liver is the principal site of vitamin B12 & stores 2 mg of Vitamin B12.
• Liver & red cells main storage sites of folate.

Etiological classification of Megaloblastic anemia-

Clinical features-

• Anemia
• Glossitis
• Neaurological manifestations- numbness, paraesthesia, weakness, ataxia.
• Charateristic triad- macro-ovalocytosis, hypersegmented neutrophils & Howell- jolly bodies.

Lab findings-

Blood picture & red cell indices-

• Hemoglobin low
• RBC- macrocytosis
• Blood smear shows anisocytosis, poikoilocytosis, macro-ovalocytosis
• Reticulocyte count is low
• MCH, MCH, MCHC decreased
• WBC count low
• Platelets count low

Bone marrow findings-

• Marrow hypercellular & decreased myeloid erythroid ratio.
• Chararcteristics megaloblastic erythropoiesis.
• Increased iron granules.
• Megakaryocytes are present in marrow.

Biochemical findings-

• Rise in serum unconjugated bilirubin.
• Serum iron & ferritin increased.

a) Test for Vitamin B12 deficiency- Schilling test & serum enzyme levels.

• To detect Vitamin B12 deficiency & detect lack of IF, malabsorption syndrome.
• Radioisotope used for labelling vitamin B12- ⁵⁸Co or ⁵⁷Co.

b) Test for folate deficiency- measurement of formiminoglutamin acid (FIGLU) urinary excretion used for assessing folate deficiency.

Treatment-

• Hydroxycobalamin IM injection 1000mg- 3 weeks.
• Oral folic acid tablet – 4 months.

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