Mohammad Ghorbani - Pathology Department, Gonabad University of Medical Sciences, Gonabad, Iran.
Babak Mahmoudi - Allameh Bohlool Hospital, Gonabad University of Medical Sciences, Gonabad, Iran.
Zahra Khoshnegah - Department of Hematology and Blood Banking, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran.
Amin Solouki - Department of Hematology and Blood Bank, School of Allied Medical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran
Mohammad Reza Javan - Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Iranian Blood Transfusion Organization (IBTO), Tehran, Iran.
Abuzar Zakeri - Hematology Department, Allameh Bohlool Hospital, Gonabad University of Medical Sciences, Gonabad, Iran.
Hamid Reza Niazkar - Student Research Committee, Gonabad University of Medical Sciences, Gonabad, Iran.
Amir Mohammad Solouki - Internal Medicine Department, School of Medicine, Birjand University of Medical Sciences, Birjand, Iran

AbstractIntroduction: platelet count errors such as PU flag, could cause misdiagnosis. Case report: a ۳۶-year-old thalassemia minor male with fever and myalgia presented. Petechiae and purpura in the lower extremities of patients were observed in physical examination. The platelet count was assessed by Nihon Kohden’s Celltac G cell and Sysmex XP-۳۰۰ cell counter and the platelet count was reported ۱۰,۰۰۰/μL and ۱۲۹,۰۰۰/μL respectively. But peripheral blood smear assessment confirms that the result of the Sysmex XP-۳۰۰ cell counter was wrong and a platelet flag was seen. This situation can be corrected by the CBC histogram and peripheral blood smear evaluation. Discussion: Sysmex XP-۳۰۰ cell counter inability to differentiate severely microcytic cells from platelets can cause the PU error, which means the severe microcytic RBCs were counted as platelets that cause the platelet count falsely higher than the actual number in this patient. The PU flag means the platelet histogram intersects the PU line and does not touch the zero baseline, that occur in conditions such as platelet clumps, giant platelet, microcytic and fragmented or dysplastic RBCs in hemolytic anemia. In Nihon Kohden’s Celltac G cell counter, due to the change in the PU line this error was prevented and the actual platelet count of the patient was reported. By the way, to avoid such errors, abnormal platelet counts should always be confirmed with the findings of PBS. ConclusionPoikilocytosis such as microcytic RBCs can cause the PU flag, so platelet and erythrocytes histograms and PBS evaluation should be assessed.

Sysmex XP-۳۰۰, Nihon Kohden’s Celltac G cell, platelet count, platelet flag, CBC histogram