#00065164

A 37 y.o. male was admitted for hemoptysis and profound thrombocytopenia (platelets < 7000/mcL).  Past medical history was significant for hypertension, anxiety and post traumatic epilepsy.  He was initially treated with steroids without response. On hospital day (HD) 3 an ADAMST13 activity result of < 3% returned, Thrombotic Thrombocytopenic Purpura (TTP) was diagnosed and plasmapheresis instituted. His platelet count sustained at > 150,000/mcL by HD 20 and he was discharged.  There has been no relapse over three years.

Panel A represents a normal RBC histogram.  The RBCs are a single population distributed symmetrically.  The solid lines are derived from the RBC population and represent the points at which 4% of the RBC population are outside the central 92%.  The dotted lines are set at 60 fL (left) or 120 fL (right) to permit quantification of the % microcytic (MCV < 60 fL) or macrocytic (> 120 fL) RBCs.

Panel B:  Evolution of this patient’s RBC histogram over time. The RBC histogram initially displays an increased microcytosis due to schistocytes.  Over time a macrocytic population emerges and represents the reticulocytosis responding to his hemolytic anemia. 

MCVs and RDW-CVs derived from RBC histograms and were correspondingly increased over time.

RBC Histograms are not currently displayed in electronic health records. Currently there is no standard configuration of hematology analyzers to transmit to laboratory information systems (LIS), or LISs to transmit these to electronic health records (EHRs), and there may be inadequate space within in EHRs to house them.  The RDW and MCV, however, are surrogates and reported with every CBC.  Trending these values over time and reviewing the individual RBC histograms with the Clinical Laboratory are the current methods to access this information.