Anemias

Definition: Anemia is defined as the decrease

in oxygen carrying capacity of the blood either due to decrease number of RBC’s or decrease Hb content.

O2 carriage

Classification of anemias:

A- According to the cause

B- According to size of RBC’s and Hb concentration

Nutritional

Aplastic

Hemolytic Hemorrhagic

Normocyticnormochromic

Microcytic hypochromic

Macrocytic hyperchromic

A- According to the cause

Hemolytic anemias

a) Intracapsular causes

b) Extracapsular causes

abnormalities in the red cell membranee.g. herditary spherocytosis

abnormalities in Hbe.g. G.6.P.deficiency

incompatible blood transfusion

certain drugs

hypersplenism

A- According to the cause

Aplastic anemia

a) Certain drugs e.gchloramphenicol

b) Exposure to gamma ray radiation or excessive X-ray treatment

c) Leukemia

d) Certain chronic infections fibrosis of B.M.

A- According to the cause

Nutritional (deficiency) anemias

• Iron deficiency anemia

• Prenicious anemia due to Vit. B12 deficiency

• Macrocytic anemia due to folic acid deficiency

Normocytic Normochromic

Microcytic hypochromic

Macrocytic hyperchromic

Size of RBC’s

normalDecreasedIncreased

HB content

normalDecreasedIncreased

CausesBlood lossHemolysisAplasticChronic

infections

Iron

deficiencyThalassemia

Vit.12 deficiencyFolic acid deficiency

B- According to size of RBC’s and Hb concentration

Effects of anemia

viscosity peripheral resistance

diastolic pressure and the venous return to the heart.

Anemic hypoxia peripheral vasodilatation venous return to the heart

The cardiac output is thus increased and workload of the heart is greatly increased

• At rest the oxygen supply to the tissues may not affected because of the increased cardiac output.

• however severe tissue hypoxia results with exercise.