Acute

The cause of an acute red cell aplasia include:

• idiopathic
• post viral infection - especially, primary atypical pneumonia, influenza, infection mononucleosis, or parvovirus
• post drug use - especially, chloramphenicol and di-phenylhydantoin.

The patient may rapidly develop pallor especially with a pre-existing haemolytic anaemia. Other features of bone marrow may be present

Laboratory analysis demonstrates anaemia, a reduced reticulocyte, reduced normal or serum bilirubin, normal or lower serum bilirubin, and normal white cell count and platelets. The bone marrow shows depletion of all erythroid elements.

Recovery is associated with reticulocytosis and bone pain secondary to bone marrow expansion. Splenectomised patients may experience an "erythroblastic crisis" - an outpouring of nucleated red cells.