Non Megaloblastic Macrocytic Anaemia

  • Macrocytic anaemias are characterised by large (in volume or size) RBCs
    • greater than 100fL
    • greater than 9um
  • Classified depending on precursors into:
    • Megaloblastic Anaemia and
    • Non-Megaloblastic Anaemia
  • Non-megaloblastic anaemia is a macrocytosis without an accompanying megablastosis

    Macrocyte Diagnosis

    Physiological Causes

    Newborn:

    • Usually not an actual anaemia
    • A newborn's blood always contains a large number of macrocytes
 

Pregnancy:

  • May be unrelated to a vitB12 or folate deficiency

Pathological Causes

Reticulocytosis:

  • Polychromasia seen on a blood film due to increased erythropoietin following haemorrhage or haemolysis

Liver Disease:

  • Round macrocytes and target cells
  • May get a normochromic microcytic anaemia

Alcohol:

    • Inc. RBC production may cover the causes of this anaemia such as hamolysis, impaired BM response (due to a direct toxic/suppressing effect), folate deficiency and blood loss
    • Significant Dec. in the length of RBC survival
    • May cause sideroblastic anaemia

 

Stem Cell Disorders:

    • Dyserythropoiesis (abnormality in morphology and function of RBCs)
    • Leukaemia
    • Myelodysplastic syndromes
 

Miscellaneous:

    • Hypoxia
    • Post splenectomy
    • Thyroid disorders

  • Note: - pseudomacrocytosis is associated with increased WCC, cold agglutinins, hyperglycaemia and increased protein levels
New look for June 2003