A FAVORABLE DECREASE IN THROMBOCYTE LEVELS CAUSED BY LMWH TREATMENT FOR A DVT PATIENT WITH REFRACTER ESSENTIAL THROMBOCYTOSIS:A case report Hakan Keski, MD, Hematology University of Health Sciences Ümraniye Educaon and Research Hospital, Clinic of Hematology Introducon: Low molecular weightheparins have been found at least as eecve as unfraconed heparin in proximal venous thrombosis and have been shown to further inhibit the in vivo thrombin generaon. Because of the various reasons, there may be some changes among the LMWHs regarding the paent’sclinical follow-ups. Case report: A 53-year-old male paent, paent weight: 88 kg For the paent JAK2 V617F posive essenal thrombocytosis (ET) was diagnosed in Haydarpaa Numune Educaon and Research Hospital in 2006. Paent has been followed in Ümraniye Educaon and Research Hospital the hematology clinic since May 2016. Medical Story (anamnesis): One month nadroparin calcium 3800 IU treatment was given to paent due to lower extremity deep vein thrombosis (DVT) in June 2008.The paent had DVT for the second me in the lower extremity in September 2013, this me enoxaparin sodium 6000 IU was given as treatment. Physical examinaon: Splenomegaly was conrmed with palpaon for 2 cm (168 mm measured with USG) Laboratory: At the me of diagnosis, WBC 10880, Hgb: 15,9 g/dl Hct % 46 Plt: 1820000, biochemical parameters such as urea, creanine, AST, ALT were normal. The paent inially received ASA 100 mg and hydroxyurea 500 mg 3x1 was also given and 3 months later, platelet value was 1750000, the paent has been accepted as refractor and anagrelide treatment has been added with the dossage 2x1, then 3x1 in addion to the current treatment. However, the paent's platelet count was decreased in the range of 1200000-1300000. The paent had recurrent DVT incident again in July 2017. Factor II G20210A gene mutaon homozygous, Factor V leiden gene mutaon heterozygous mutant is detected in the genec tests sent by the microarray method. Bemiparin sodium 5000 IU 2x1was started this me in the last deep vein thrombosis aack.Due to a disease with disturbed platelet funcons such as ET accompanying the paent , bemiparin sodium dosage had been organized twice daily for this paent. Furthermore by this posology, the paent’s risk of bleeding due to drug interacons such as 100mg ASA was also minimized. While the paent has been using the LMWHmedicaonduring the 3 months , paent’s platelet counts ranged from 650000-700000. Discussion: Decrease in platelet values is one of the rare side eects of LMWHs.In our case we evaluated this adverse eect of LMWHs for consolidaon of our treatment and to increase in the treatment response. Conclusion: We observed a favorable decrease in thrombocyte levels of the paent with cytoreducve-resistant thrombocytosis by adding LMWH into the treatment. 8--P Use of LMWH for the management of VTE in clinical practice 1st International Encounter in Thrombosis and Hakan Keski Hematology IETH2018.