Thrombocytopenia is one of the most common abnormalities which can be observed in blood counts. Measurement of immature platelet fraction (IPF) on haematology analysers is a promising tool to discriminate central from peripheral thrombocytopenia, then avoiding bone marrow aspiration to assess megakaryocyte density. Nevertheless, most of the studies have been conducted on Sysmex XE analysers, which are less sensitive and specific for IPF measurement than new generation Sysmex XN-10 haemaocytometers.

In this study, we analyzed %IPF in a retrospective cohort of 45 patients who underwent bone marrow aspiration to explore thrombocytopenia to establish a cut-off value to distinguish a peripheral from a central mechanism of thrombocytopenia.

We performed ROC curve analysis and with a cut-off value of IPF% ≥ 13%, specificity and predictive positive value (PPV) were 100%. This cut-off value was then validated in two other French hospitals and finally, we tested this cut-off value in a prospective study (72 patients) which confirmed the reliability of IPF to discriminate central and peripheral thrombocytopenia.

A% IPF ≥ 13% on Sysmex XN haemocytometers is predictive of peripheral thrombocypenia and this measurement could avoid bone marrow aspirations, especially when thrombocytopenia is the sole abnormality infull blood count.