MEGALOBLASTIC ANEMIA

37 Pages·2013·0.65 MB·English

M
EGALOBLASTIC
ANEMIA
MACROCYTIC ANEMIAS
These are the anemias in which the RBC have

an MCV of greater than 100fl
There are 2 groups of macrocytic anemias:

Megaloblastic anemia
1.
Non megaloblastic macrocytic anemia
2.
R R B C
EQUIREMENTS FOR ED LOOD ELL
P
RODUCTION
Erythropoeitin

Proteins, required for globin synthesis

Iron

Vitamin B12 and folic acid

Vitamin B6

Vitamin C

Thyroid hormones, estrogens and androgens

D :
EFINITION
Megaloblastic anemia (or megaloblastic anaemia) is

an anemia (of macrocytic classification) that results from
inhibition of DNA synthesis in red blood cell production.When
DNA synthesis is impaired, the cell cycle cannot progress from
the G2 growth stage to the mitosis (M) stage. This leads to
continuing cell growth without division, which presents as
macrocytosis.
Vitamin B and folic acid are important nutrients required in

12
the process of nuclear maturation
They are required during erythropoiesis (during DNA

synthesis)
Impaired DNA synthesis leading to defective cell maturation

and cell division
The defeciency of the folic acid and B12 lead to megaloblastic

anemia
Folic Acid:

It a vitamin which yellow in colour, water

soluble, necessary for the production of the
RBC, WBC and platelets.
It is not synthesized in the body.

It is found in large number of green fresh

vegetables, fruits.
Daily requirement:

The human body needs about 100-150 µg daily.
Absorption:

It is absorbed in the Duodenum and Jejunum.
Transportation:

Weakly bound to albumin.

METABOLIC FUNCTION
Purine synthesis
1.
Conversion of homocysteine to methionine ( which
2.
also requires B12 )
FOLIC ACID DEFICIENCY
INCREASED DEMAND
1.
DECREASED INTAKE
2.
DECREASED ABSORPTION
3.
METABOLIC INHIBITION
4.
INCREASED DEMAND
Pregnancy

Lactation

Infancy

Puberty and growth period

Patients with chronic hemolytic anemias

Disseminated cancer

DECREASED INTAKE
Elderly

Lower socio economic status

Chronic alcoholics
