Recommendation for standardization of haematology reporting units used in the extended blood count

The diversity in use of reporting units occurs in three areas: the persistence in use of non-SI units for RBC, WBC and platelet counts, the use of three different units for haemoglobin concentration and the manual reporting of WBC differential, reticulocytes and nucleated RBCs when the latter are available from automated analysis or can be expressed as absolute numbers by calculation. A new recommendation with a rationale for each parameter is made for standardization of the reporting units used for the extended blood count.