Introduction
Anaemia is defined as a reduction in the haemoglobin concentration, red blood cell (RBC) count, or haematocrit below the normal reference range for age and sex. This reduction leads to impaired oxygen delivery to body tissues, resulting in a wide range of systemic symptoms.
Pathophysiology
Anaemia develops when there is an imbalance between red blood cell production and destruction, or when blood loss exceeds the body’s capacity to replace RBCs. The major mechanisms include:
-Reduced Red Blood Cell Production
-Nutritional deficiencies (iron, vitamin B₁₂, folate)
-Bone marrow suppression or failure
-Chronic inflammatory or systemic diseases
-Increased Red Blood Cell Destruction
-Haemolytic anaemia due to genetic or acquired causes
-Autoimmune conditions
-Enzyme deficiencies such as G6PD deficiency
-Blood Loss
-Acute (trauma, surgery)
-Chronic (gastrointestinal bleeding, menorrhagia)
Each mechanism affects red blood cell lifespan and haemoglobin synthesis differently, leading to varying clinical and laboratory presentations.
Classification of Anaemia
A. Based on Red Cell Morphology
Microcytic anaemia (low MCV): Iron deficiency, thalassaemia.
Normocytic anaemia: Acute blood loss, anaemia of chronic disease
Macrocytic anaemia: Vitamin B₁₂ or folate deficiency
B. Based on Aetiology
Nutritional anaemia
Haemolytic anaemia
Anaemia of chronic disease
Bone marrow failure anaemia
Causes of Anaemia
1. Nutritional Deficiencies
Iron deficiency: Most common cause worldwide; due to poor intake, malabsorption, or chronic blood loss
Vitamin B₁₂ deficiency: Seen in malabsorption syndromes, prolonged vegetarian diets, and pernicious anaemia
Folate deficiency: Common in pregnancy, alcoholism, and chronic haemolysis
2. Chronic Diseases
Chronic infections, renal disease, and inflammatory disorders reduce erythropoietin production and impair iron utilization.
3. Genetic and Haemolytic Conditions
Conditions such as sickle cell disease result in premature RBC destruction, leading to chronic anaemia.
Clinical Features
General Symptoms:
-Fatigue and reduced exercise tolerance
-Weakness and lethargy
-Dizziness and headaches
-Shortness of breath on exertion
-Palpitations and tachycardia
-Pallor of the skin and mucous membranes
-Brittle nails and hair loss (iron deficiency)
-Glossitis and angular stomatitis
Severity of symptoms depends on the degree of anaemia and the speed of onset.
Diagnosis and Laboratory Investigations
Full Blood Count (FBC): Haemoglobin level, RBC indices (MCV, MCH)
Peripheral Blood Film: Morphological assessment of RBCs
Serum Ferritin: Assessment of iron stores, serum Vitamin B₁₂ and Folate Levels
Reticulocyte Count: Bone marrow response
Pharmacological Management
Management is cause specific and aims to correct the underlying defect.
1. Iron Deficiency Anaemia
Oral Iron Therapy
Ferrous sulphate 200 mg two to three times daily
Ferrous fumarate or gluconate as alternatives
Counseling Points
Best absorbed on an empty stomach
Vitamin C enhances absorption
Common side effects:
constipation, nausea, dark stools
2. Vitamin B₁₂ Deficiency Anaemia
Hydroxocobalamin injection
Initial loading doses followed by maintenance therapy
Lifelong treatment may be required in pernicious anaemia
3. Folic Acid Deficiency Anaemia
Folic acid 5 mg once daily
Important to rule out vitamin B₁₂ deficiency before initiation
4. Anaemia of Chronic Disease
Management of underlying condition
Iron supplementation only when iron deficiency is confirmed
Conclusion
Anaemia is a multifactorial condition with diverse clinical and pharmacological considerations. Accurate diagnosis, appropriate drug selection, and effective patient counseling are essential for optimal outcomes.
