Anaemia is present when there is a decrease in haemoglobin in the blood below the reference level for the age and sex of the individual - Hb <130g/L in adult males (Hct <0.38) and Hb <120g/L in adult females (Hct <0.37)

Pathophysiology

• Normal response to anaemia is to make more red cells (reticulocytosis)
  • Upregulation takes a few days
  • Reticulocytes: cells that have just left the bone marrow
    • Larger than average red cells
    • Still have remnants of RNA - stain purple/deeper red, blood film appears ‘polychromatic’

Pathophysiological classification of anaemia

• Decreased production - low reticulocyte count
  • Hypoproliferative - reduced amount of erythropoiesis
  • Maturation abnormality - erythropoiesis present but ineffective
    • Cytoplasmic defects - impaired haemoglobinisation
    • Nuclear defects - impaired cell division
• Increased loss or destruction of red cells - high reticulocyte count
  • Bleeding
  • Haemolysis

Clinical features

Symptoms

• The symptoms of anaemia are non-specific and include breathlessness, fatigue, headaches, palpitations and faintness

Signs

• Pallor
• Tachycardia
• Systolic flow murmur
• Cardiac failure

Investigations

• Bloods: FBC
  • Hb concentraton, MCV, haematocrit, mean cell haemoglobin, mean cell haemaglobin concentration
• Blood film: look at cellular morphology
• Reticulocyte count: assess marrow response
• Additional tests - depending on clinical details and lab findings