Incidence of reactive thrombocytosis in serious bacterial infections in children aged two months to twelve years and its usefulness as a predictor of serious bacterial infections

Background: The aims of the study were to estimate the incidence of reactive thrombocytosis(RT) among febrile children aged 2 months to 12 years and to identify any differences in age group and gender in mounting thrombocytosis as a response to infection, to identify if thrombocytosis occurred preferentially in any particular group of serious bacterial infections(SBI), to compare thrombocytosis with other parameters like total white cell count, C-reactive protein(CRP), cultures etc. and to assess the utility of platelet count as a potential predictor of serious bacterial infection.Methods: This was a prospective study done in Institute of Child Health and Hospital for children, Madras Medical College from September 2015 to July 2016. Inclusion criteria: Children aged 2 months to 12 years with symptoms of fever less than 6 days admitted in the paediatric wards and those seen at the outpatient department. Exclusion criteria: Children having received parenteral antibiotics.Results: Of the 500 children, 142 (28.4%) had reactive thrombocytosis. RT was mild in 120 children (24%), moderate in 16 children (3.2%), severe in 4(0.8%) and extreme in two children (0.4%). This study showed that 36.48% (85 / 233) of children under 1 year had RT (p = 0.0002).There was no significant sex related difference in mounting RT. Out of 500 children included in the study, serious bacterial infection was diagnosed among 171 children (34.2%).Pneumonia (n=100) was the most common SBI followed by urinary tract infections (n=33), meningitis (n=23), sepsis (n=15). This study showed that RT has a moderate ability to predict serious bacterial infections (AUC=0.78; PPV-75.35%).Conclusions: Incidence of reactive thrombocytosis in febrile children aged 2 months to 12 years is 28.4%. It occurs more frequently in infants and without any sex predilection. RT is associated with leucocytosis, positive CRP, positive Chest X ray findings, positive urine culture and positive CSF findings. This shows that RT has a moderate ability in predicting SBI in children.

A cross-sectional retrospective study to analyze the underlying causes and clinical characteristics of children with reactive thrombocytosis at a Korean tertiary medical center

BACKGROUND: Reactive thrombocytosis (RT) is a common condition among children, although no studies have examined the etiology or clinical characteristics of RT among Korean children. METHODS: This retrospective study evaluated children with RT at a single Korean tertiary center during a 10-year period. RESULTS: RT accounted for 13.5% of children who were admitted to the pediatric ward (4,113/30,355): mild RT, 82.7%; moderate RT, 14.1%; severe RT, 1.1%; and extreme RT, 2.1%. There was a negative correlation between platelet count and Hb level (P=0.008). There were positive correlations between platelet count and WBC (P=0.001), erythrocyte sedimentation rate (ESR) (P=0.007), and admission duration (P=0.006). The most common cause of RT was infection and the second most common was Kawasaki disease (KD). The highest proportion of lower respiratory tract infection was observed in extreme RT (P < 0.001). The proportion of KD was highest in extreme RT (P < 0.001) and in children aged 1–7.9 years (P < 0.001). The proportion of refractory KD was highest in extreme RT (P=0.005). In cases of KD, there was a positive correlation between platelet count and fever duration (P=0.006). Non-KD autoimmune inflammation was only observed in mild/moderate RT, and its proportion was highest in children aged 8–18 years (P < 0.001). CONCLUSION: In children, more severe RT was associated with lower Hb, increased WBC, ESR, and prolonged admission. With respiratory infection or KD, extreme RT was associated with more severe disease course.

Prolonged Extreme Thrombocytosis in a Postsplenectomy Patient with Hereditary Spherocytosis / 대한혈액학회지

We report a case of prolonged extreme reactive thrombocytosis in a post-splenectomy patient with hereditary spherocytosis. A 29-year-old female patient presented with gall stones detected incidentally by abdominal ultrasonography. Her laboratory findings showed hemolytic anemia with spherocytosis on the peripheral blood smear and increased osmotic fragility. She was diagnosed with hereditary spherocytosis and underwent a laparoscopic cholecystectomy and splenectomy. After undergoing surgery, the hemolytic anemia was resolved but thrombocytosis was newly detected. Nineteen months after the splenectomy, the thrombocytosis was still persistent and extremely high. To our knowledge, this is the first report of a prolonged extreme reactive thrombocytosis after a splenectomy in Korea.

Evaluation of Platelet Indices for Differential Diagnosis of Thrombocytosis by ADVIA 120 / 대한진단검사의학회지

BACKGROUND: For the diagnosis of essential thrombocythemia (ET), no single clinical or laboratory finding of diagnostic value is available and a differential diagnosis of other myeloproliferative neoplasms or reactive thrombocytosis (RT) is needed. Following recent developments in automated blood cell analyzers, various platelet indices can now be measured. In this study, we analyzed whether platelet counts and 6 platelet indices can be used for the differentiation of ET from RT in patients with a platelet count of 600x10(3)/microliter or more. METHODS: The subjects studied were 31 patients with ET and 224 patients with RT. The platelet counts, mean platelet volume (MPV), plateletcrit (PCT), platelet distribution width (PDW), mean platelet mass (MPM), mean platelet component concentration (MPC) and large platelets (LPLT) were measured by ADVIA 120 (Bayer Diagnostics, USA). The mean values of each item were compared between the two patient groups and the sensitivity and specificity of each item in the diagnosis of ET were determined by ROC curve analysis. RESULTS: In essential thrombocythemia, all parameters except MPC were significantly higher than in reactive thrombocytosis. For the diagnosis of ET, the sensitivity and specificity were: 74.2% and 84.4%, when the platelet count was > or = 820x10(3)/microliter; 80.6% and 80.0%, when the plateletcrit was > or =0.63%; and 64.5% and 99.1%, respectively, when LPLT was > or = 23x10(3)/microliter. CONCLUSIONS: The platelet counts and platelet indices are useful for the differential diagnosis of thrombocytosis. The plateletcrit and LPLT are particularly useful for the diagnosis of ET when the platelet count is markedly increased.

JAK2(V617F) Mutation in Korean Patients with Essential Thrombocythemia / 대한진단검사의학회지

BACKGROUND: Essential thrombocythemia (ET) is thought to reflect transformation of a multipotent hematopoietic stem cell, but its molecular pathogenesis remains obscure. But tyrosine kinase, especially Janus kinase 2 (JAK2), has been implicated in myeloproliferative disorders other than chronic myeloid leukemia. We investigated the frequency of JAK2 mutation and its correlation with other clinicopathologic variables in Korean patients with ET and reactive thrombocytosis (RT). METHODS: JAK2 mutation analysis was performed on genomic DNA from bone marrow aspirates of 24 patients with ET and peripheral blood in 36 patients with RT using allele-specific PCR. RESULTS: JAK2 mutation was detected in 11 patients (46%) among the 24 patients with ET and was not found in 36 patients with RT. In patients with ET, older age and leukocytosis were related with JAK2 mutation without statistical significance (P=0.172 and 0.094, respectively). But this mutation was not correlated with sex, hemoglobin, platelet count, splenomegaly, increased cellularity of bone marrow, bone marrow fibrosis and vascular complications. CONCLUSIONS: The current observation strengthens the specific association between JAK2 mutation and ET. At the diagnosis of ET in Korean patients, identification of JAK2 mutation should be incorporated in the basis for new approaches.

Pattern of Von Willebrand Factor Antigen and Large Von Willebrand Factor Multimer in Myeloproliferative Disorder and Reactive Thrombocytosis / 대한혈액학회지

BACKGROUND: Von Willebrand factor (vWf) plays a crucial role in the early phase of hemostasis. Acquired von Willebrand disease (vWD) due to abnormalities of vWf multimers has been reported in patients with myeloproliferative disorders (MPD) who have high platelet counts. We compared the distribution of plasma vWf antigen and large vWf multimers in samples obtained from patients with MPD and reactive thrombocytosis (RT). Furthermore, we tried to find the relationship between the decrease of large vWf multimers in plasma and the bleeding complication. METHODS: Sixteen patients with MPD and twenty-five patients with RT with more than 600x103/microliter of platelets were included in the study. The numbers of platelets and leukocytes, platelet distribution width (PDW), mean platelet volume (MPV), platelet-large cell ratio (P-LCR), vWf : Ag and vWf multimers were measured. RESULTS: The mean values of platelets and leukocytes were 1,091x103/microliter, 82.9x103/ in MPD and 763x103/, 11.4x103/ in RT (P<0.05). Platelet parameters such as MPV,PDW, P-LCR were 11.2 fL, 10.2%, 28.6% in MPD, and 9.6 fL, 9.9%, 19.6% in RT (P<0.05). The levels of vWf : Ag and large vWf multimer were 120.8 U/dL, 13.8% in MPD and 184.3 U/ dL, 20.7% in RT (P<0.05). Large vWf multimers were decreased in 11 MPDs and 2 RTs. Bleeding diathesis appeared only in 2 MPDs with decreased large vWf multimers. Platelet or leukocyte count was inversely correlated with large vWf multimers, but vWf antigen was correlated with large vWf multimer. CONCLUSION: The findings of normal vWf antigen level and decreased percentage of large vWf multimers are more frequent in MPD than in RT, and the measurement of these parameters is useful to differentiate MPD from RT. Bleeding complication in the patients with MPD with decreased large vWf multimers might be prevented by correction of decreased large vWf multimers.