Page 318 - Concise Pathology for Exam Preparation ( PDFDrive )

12 Haematology 303

Pathogenesis (Flowchart 12.6)

Chronic infection, inflammation and malignancy

Secretion of cytokines by monocytes and T lymphocytes

Increased uptake Inadequate Direct inhibition Shortened
and sequestration of production and of erythroid red cell
iron in macrophages poor response progenitor cells survival
and blockade in the to erythropoietin
release of iron from
macrophages/RES
FLOWCHART 12.6. Pathogenesis of anaemia of chronic disease.

• Restricted movement of iron from reticuloendothelial system (RES) to erythroid cells is
due to:
• Production of lactoferrin by inflammatory cells (lactoferrin avidly binds iron; iron
bound to lactoferrin is shunted to macrophages as there are no receptors for lactofer-
rin on erythroid cells)
• Increased synthesis of apoferritin in inflammation (apoferritin binds to increased
amounts of iron and diverts circulating iron to storage pool)

Laboratory Investigations

• Peripheral smear shows normocytic normochromic anaemia.
• Serum iron, transferring levels and total iron-binding capacity are reduced.
• Ferritin levels are elevated and reticuloendothelial iron is increased.

Q. Classify haemolytic anaemia.

Ans. Haemolytic anaemias have been classified in Table 12.8.

TABLE 12.8. Classification of haemolytic anaemias
Intrinsic/intracorpuscular abnormalities Extrinsic/extracorpuscular abnormalities
Hereditary Immune haemolytic anaemia
• Membrane cytoskeleton disorders: • Autoimmune (idiopathic, SLE, malignant neoplasms)
Spherocytosis and elliptocytosis • Alloimmune
• Red cell enzyme deficiency: • Drug induced
Pyruvate kinase, G6PD Mechanical trauma to red cells (microangiopathic
• Disorders of haemoglobin synthesis haemolytic anaemia)
• Deficient globin synthesis, eg, thalassaemia Thrombotic thrombocytopenic purpura (TTP), DIC and
syndrome prosthetic heart valves
• Structural abnormality of globin chain Infections
(haemoglobinopathies), eg, sickle cell anaemia Malaria and bacterial diseases
Acquired Chemical injury
• Membrane defect: Lead poisoning
Paroxysmal nocturnal haemoglobinuria (PNH) Sequestration in mononuclear phagocyte system
Hypersplenism

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