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Aplastic Anaemia

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Overview

Aplastic anaemia is characterised by pancytopenia due to the bone marrow being unable to generate new mature cells. There is no abnormal bone marrow infiltrate or marrow fibrosis. This section is a summary of aplastic anaemia.

Causes

Acquired

  • Idiopathic (70%) of cases
  • Congenital e.g. Fanconi anaemia
  • Infection: parvovirus B19, Epstein-Barr virus (EBV), HIV, hepatitis
  • Drugs: NSAIDs, chloramphenicol, carbamazepine, phenytoin
  • Aplastic crises in sickle-cell anaemia

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.

Example History

A 29-year-old man has had a heavy nosebleed that required cauterisation to stop. His medical history consists of epilepsy and he takes phenytoin.

Investigations:

Haemoglobin:92 g/L(115 – 140 g/L)
Platelets:24 x 109/L(150 – 450 x 109/L)
Mean cell volume (MCV):95 fL(76.0 – 98.0 fL)
White blood cells (WBC):1.1 x 109/L(5.0 – 12.0 x 109/L)

Presentation

Patients often present with the following:

Investigations

All patients

  • FBC and differential:
    • There must be two of the following:
      • Haemoglobin <100 g/L
      • Platelet count <50 x 109/L
      • Neutrophil count <1.5 x 109/L
  • Reticulocyte count:
    • Usually low due to the bone marrow being unable to generate new cells
  • Bone marrow biopsy:
    • Definitive diagnostic test, shows hypocellular marrow with no abnormal cells

Other investigations

Other investigations should be considered to find an underlying cause:

  • B12 and folate
  • LFTs
  • HIV testing
  • Autoantibodies
  • Chest x-ray for malignancy
  • Abdominal ultrasound for malignancy

Diagnosis

To diagnose aplastic anaemia, there must be two of the following:

  • Haemoglobin <100 g/L
  • Platelet count <50 x 109/L
  • Neutrophil count <1.5 x 109/L

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