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Anaemia of Chronic Disease

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Overview

Anaemia of chronic disease (AOCD) describes anaemia secondary to chronic infection, chronic inflammation, malignancy or chronic kidney disease.

Its pathophysiology is not fully understood, however, it is thought to be due to:

  • Decreased serum iron availability
  • Reduced erythropoietin release
  • Reduced red blood cell lifespan

Inflammation stimulates the release of hepcidin (an acute-phase reactant). This reduces serum iron by trapping it in macrophages and liver cells and reduces iron absorption. This is thought to reduce the amount of iron available for microorganism growth.

It may be helpful to look at the chapter on Anaemia: Data Interpretation alongside reading this section to help wrap your head around when to suspect what type of anaemia.

Causes

The underlying causes of inflammation may be:

Causes of anaemia of chronic disease

Presentation

Patients usually have signs and symptoms of anaemia on a background of chronic disease. Features are:

Differential Diagnoses

Iron-deficiency anaemia (IDA)

  • IDA and AOCD may co-exist
  • In general, IDA has a lower serum iron, low transferrin saturation, low ferritin, and raised total iron-binding capacity (TIBC)

Thalassaemia

  • More likely if the Mentzer index is <13

Investigations

All patients

  • Full blood count (FBC):
    • Haemoglobin:
      • Low
    • Platelets:
      • Usually normal but can be deranged
    • Mean cell volume:
      • Normal or reduced
    • Mean corpuscular haemoglobin (MCH):
      • Normal or reduced
    • Mean corpuscular haemoglobin concentration (MCHC):
      • Normal or reduced
    • Red cell distribution width (RDW):
      • Normal or increased
  • Blood film:
    • Small, pale (hypochromic) red cells with:
    • Reticulocyte count: low – usually due to underproduction in the marrow
  • Iron studies:
    • Serum iron:
      • Reduced
    • Total iron-binding capacity (TIBC):
      • Normal or reduced
      • Unlike IDA, due to underlying inflammation/infection etc., TIBC is low because transferrin is a negative acute-phase reactant, therefore, there are fewer binding ‘spots’ for iron 
    • Serum ferritin:
      • Normal or increased
      • Ferritin is an acute phase reactant, so it is normal or elevated in AOCD
    • Transferrin saturation:
      • Reduced
      • Transferrin is a negative acute-phase reactant and there is less iron in the blood as it is trapped in macrophages and liver cells, meaning fewer ‘spots’ are taken up on ferritin
  • Urea and electrolytes (U&Es):
    • May identify renal disease, which can be a cause of AOCD

Example blood tests

Haemoglobin:104 g/L(130 – 180 g/L)
Platelets:205 x 109/L(150 – 450 x 109/L)
Mean cell volume (MCV):67.5 fL(76.0 – 98.0 fL)
White blood cells:8.5 x 109/L(3.00 – 10.0 x 109/L)
Serum iron:10.3 μmol/L(11.6 – 35.0 μmol/L)
Serum ferritin:365 ng/mL(25 – 350 ng/mL)
Total iron-binding capacity (TIBC):32 μmol/​L(45 – 81 μmol/​L)

Management

All patients

  • 1st-line: manage the underlying cause
    • The anaemia usually resolves following this
  • Consider iron supplements, erythropoiesis-stimulating agents, and blood transfusion depending on severity.

Complications

  • High-output heart failure or worsening of heart failure
    • More likely if anaemia is severe (usually <50 g/L)
  • Angina
  • Fatigue

Prognosis

  • The prognosis depends on the underlying cause and factors regarding the patient such as age, comorbidities etc.

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