Clinical Definition of Severe Aplastic Anemia

Severe Aplastic Anemia is defined as follows:

Bone marrow cellularity < 25%, or marrow cellularity < 50% but with < 30% residual hematopoietic cells.

Two out of three of the following (in peripheral blood): neutrophils < 0.5 x 10^9/L; platelets < 20 x 10^9/L; reticulocytes < 20 x 10^9/L. SAA diagnostic criteria may be applied to assessment at initial diagnosis or to the follow-up assessments.