Definition:

It is a clinical condition in which there is qualitative or quantitative reduction of Haemoglobin (Hb) level below the lower limit of its normal range for the age and sex of the individual.

Classification of anemia:

Classification of anemia is given below-

1. Aetiological classification of anemia(Causes of anemia):

i) Haemorrhagic(Blood loss) anaemia:
a) Acute
i. Surgical
ii. Accidental
b) Chronic
i. Bleeding peptic ulcer
ii. Hookworm infestation
iii. Menorrhagia
iv. Bleeding piles
v. Epistaxis
vi. Ruptured esophageal varices
vii. Carcinoma of stomach or colon

ii) Impaired red cell production:
a) Inadequate supply of essential elements for erythropoisis
i. Iron deficiency anaemia
ii. Vit-B12 deficiency
iii. Folic acid deficiency
iv. Protein – calorie malnutrition (Nutritional anaemia)
b) Anaemia due to replacement of normal bone marrow
i. Lymphoma
ii. Leukemia
iii. Myeloproliferative disorders
iv. Myelodysplastic disorders
v. Myeloma
c) Depression of erythropoietic activity
d) Aplastic anaemia
e) Anaemia associated with chronic disorders
i. Connective tissue disorders
ii. Infection
iii. Inflammatory disorders
iv. Disseminated malignancy
f) Anaemia associated with renal failure
g) Anaemia due to inherited disorders, e.g. Thalassaemia.

iii) Haemolytic anaemia (Due to excessive red cell destruction):

1. Intracorpuscular defect (due to intrinsic defects in red cells)
I) Congenital
a. Membrane defects
i) Hereditary spherocytosis
ii) Hereditary eliptocytosis
iii) Hereditary xerocytosis and hydrocytosis
b. Haemoglobin defects
i) Haemoglobinopathies:

• Sickle cell anaemia
• Unstable haemoglobin disease

ii) Thalassaemia:

• Beta-thalassaemia major
• Hb-H disease

iii) Double heterozygous disorders: Sickle cell beta-thalassaemia
c. Red cell enzyme defects
1) Non-spherocytic congenital haemolytic anaemia

• Glucose 6- phosphate dehydrogenase deficiency
• Pyruvate kinase deficiency

2) Drug induced haemolytic anaemia and favism
II) Acquired:
Paroxysmal nocturnal haemoglobinuria (PNH)

2. Extracorpuscular effect (due to extrinsic effects on red cells)
Acquired:
a. Immune mechanisms
1. Autoimmune acquired haemolytic anaemia

• iWarm antibody
• Cold antibody

2. Incompatible blood transfusion
3. Haemolytic disease of new born
4. Drug induced haemolytic anaemia
b. Non immune mechanisms
Mechanical haemolytic anaemia

• Cardiac haemolytic anaemia
• Microangiopathic haemolytic anaemia
• March haemoglobinuria

c. Miscellaneous
1. Infection

• C. perfringes
• Malaria

2. Drugs and chemicals
3. Burn
4. Lead (Pb) poisoing

2. Morphological classification of anemia:

Causes of anaemia in children:

1. Iron deficiency anaemia
2. Parasitic infestation
3. Congenital haemolytic anaemia
4. Leukemia
5. Aplastic anaemia
6. Anaemia of chronic disease

• Prolonged infection
• Renal diseases.