MEALOBLASTIC ANEMIA its causes,signs,symptoms,diagnosis,treatment and its specific feature

MEALOBLASTIC ANEMIA

Definition :

 It is a macrocytic anemia , results from impaired synthesis of  DNA.

It is either due to:

       1-deficiency of vitamin B12

       2-deficiency of folic acid

Pathogenesis:

Vitamin B12 or folate deficiency results in impaired synthesis of DNA inside the cell and so RNA : DNA ratio will increase resulting in lare cell with increased cytoplasmic nuclear ratio  ending in formation of a cell with mature cytoplasm and immature nucleus i.e nuclear – cytoplasmic dissociation or a synchronism.

  

The net result is :

      1- Ineffective erythropoiesis

      2-Reduction in red cell life span

 

     1-Megaloblastic anemia due to vitamin B 12 deficiency

* Vitamin  B12

          - Synthesized by microorganisms.

      .  -Minimal daily requirement is from 1-5 ug

          - Peptic enzymes and acidity of gastric juice are essential for liberation of vitamin B12 from the food ingested. 

-Intrinsic factor (If) is essential for ileal absorption of ingested vitamin B12.

Clinical picture  

 * Non specific manifestations :

     .   -Slowly progressing anemia

      .    -Increased serum levels of LDH 

Specific features: *

  (1) Neurologic Manifestations .

  (2)   Reduction of vitamin B12 in the blood (N 150-               450 pg/ml).

  (3) Rapid improvement wit B12 therapy within                     hours 

Specific Syndromes of vitamin B12 deficiency:

Pernicious anemia

  

- Addisonian                 :     atrophic gastritis

- Non addisonian          :  other causes

- Juvenile                      :  congenital deficiency of                                                        intrinsic factor

Treatment :  

Intramuscular injection of vitamin  B12

500-1000 ug  Im /day for first two weeks

          Then  500-1000 u g  Im / day , twice weekly for the next 4 weeks

          Then  500 – 1000 ug  Im . every month for life

        If neurologic manifestations are present the dose is given every 2 weeks for 6 month  

  2- Megaloblastic anemia due to folate deficiency

 Folate co – enzymes are necessary for  metabolism in animal cells.

Clinical Picture :

Non specific feature:

                                       Glossitis.

                                        Slowly developed anemia.

                                     .     Increased LDH levels

Specific feature:

Reduced folate levels in  the blood  ( N  6-12 ng /ml)

Reduced red cell folate      (N  150 –600 ng /ml).

Full clinical response to folic acid therapy.

Oral folic tablets of 1 mg (2mg / day ) for 4-5 months.