Aplastic anaemia

Key information

Appropriate Tests

Varying degrees of pancytopenia without splenomegaly

Full blood count, Reticulocyte count. Blood film.

The diagnosis is established by Bone marrow biopsy, aspirate and trephine, which are generally indicated unless the pancytopenia is a predictable effect of drugs and/or irradiation (specialist input recommended).

Aplastic anaemia is classified into mild, moderate and severe based on the bone marrow cellularity and degree of cytopenias.

The differential diagnosis includes other congenital and acquired forms of bone marrow failure (including Acute leukaemia, Myelodysplastic syndromes and marrow replacement with fibrosis or tumour), Megaloblastic anaemia and Paroxysmal nocturnal haemoglobinuria (PNH). The FBC and Bone marrow biopsy results will mostly be able to differentiate these from aplastic anaemia, however hypoplastic MDS can be difficult to distinguish, and aplastic anaemia and PNH can occur together.

See also Anaemia - normochromic, macrocytic and Pancytopenia.

Aplastic anaemia may be idiopathic or secondary to the following causes:



  • Antithyroid medication
  • Chloramphenicol
  • Sulphonamides
    • NSAIDs
    • Gold
  • Anticonvulsants, especially hydrantoins, carbamazepine
  • Nifedipine
  • Zidovudine (AZT)

Many drugs and toxins have been associated with aplastic anaemia. A full drug history including complementary medicines), and occupational history should be taken.

Susceptibility to azathioprine and 6-mercaptopurine is increased in patients with Thiopurine methyltransferase.

  • Insecticide exposure
  • Benzene
  • Solvents

Viral infection

  • Viral hepatitis
  • Parvovirus B19 infection
  • EBV
  • HIV

Viral serology (see Epstein-Barr virus serology, Parvovirus B19 Ab, Hepatitis, HIV infection)


  • Fanconi's anaemia

Inherited aplastic anaemia. Cytogenetics - constitutional; Molecular genetics.



Paroxysmal nocturnal haemoglobinuria (PNH)

Paroxysmal nocturnal haemoglobinuria

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