Aetiology and clinical significance of thrombocytosis: analysis of 732 patients with an elevated platelet count

Etiology of thrombocytosis in a general medicine population: analysis of 801 cases with emphasis on infectious causes

BACKGROUND

The clinical importance of an elevated platelet count is often overlooked, particularly as a diagnostic clue to the presence of an underlying infection. We sought to better describe the relationship between thrombocytosis and inflammatory conditions, with a focus on infectious causes.

METHODS

We retrospectively reviewed 801 sequential cases of thrombocytosis (platelet count > 500 × 10(9)/L) at a tertiary care hospital.

RESULTS

Essential thrombocythemia was the most common cause of primary thrombocytosis, and these patients were more likely to have extreme (> 800 × 10(9)/L) and prolonged (> 1 month) thrombocytosis. Secondary thrombocytosis was more common than primary, with infectious causes accounting for nearly half the cases. Demographic factors associated with an infectious etiology included inpatient status, quadriplegia/paraplegia, an indwelling prosthesis, dementia and diabetes. Clinical and laboratory characteristics associated with an infectious cause of thrombocytosis included fever, tachycardia, weight loss, hypoalbuminemia, neutrophilia, leukocytosis and anemia. Patients with thrombocytosis secondary to infection had a more rapid normalization of platelet count, but higher risk of dying, than those with secondary, non-infectious causes.

CONCLUSIONS

Infection is a common cause of thrombocytosis and should be considered in patients with comorbidities that increase risk of infection and when clinical and/or laboratory data support an infectious etiology. Thrombocytosis may have prognostic implications as a clinical parameter.

Examination of the Relationship Between Antimicrobials and Thrombocytosis

Objective:

To evaluate whether there is a relationship between antimicrobial therapy and the development of thrombocytosis.

Data Sources:

Literature was accessed through EMBASE (1977-June 2012) and MEDLINE (1977-June 2012) using the terms thrombocytosis and antimicrobial. In addition, reference citations from publications identified were reviewed.

Study Selection and Data Extraction:

All English-language publications identified were evaluated. For case reports, the Naranjo probability scale was used to calculate the likelihood of the drug causing the reaction.

Data Synthesis:

Thrombocytosis occurring during antimicrobial therapy is well documented, with several case reports and clinical trial observations. However, a direct causal relationship is not yet supported by the available literature. Platelets are welt known to be an acute phase reactant, with an elevated count occurring after acute conditions such as blood loss, inflammation, or infection. Thrombocytosis during antimicrobial therapy may be the result of an infectious process and not an adverse drug event.

Conclusions:

Based on the current available literature, a definitive link cannot be established between antimicrobial therapy and occurrence of thrombocytosis.

Postsplenectomy reactive thrombocytosis

Thrombocytosis is frequently encountered as an incidental laboratory finding. The most common etiology is reactive (secondary) thrombocytosis due to infections, trauma, surgery, or occult malignancy. Even though thrombocytosis is benign and self-limiting in most cases, it can result in hemorrhage or thrombosis. The hypercoagulable state is characterized by episodes of thrombosis and can be due to inherited or acquired conditions. Extreme thrombocytosis may result in thrombotic events such as acute myocardial infarction, mesenteric vein thrombosis, and pulmonary embolism. It is important for physicians to be familiar with the complications associated with thrombocytosis. Postsplenectomy reactive thrombocytosis has an incidence of about 75% to 82%. Thrombosis in association with elevated platelet count after splenectomy is well recognized, with an incidence of approximately 5%. This case report describes a 61-year-old patient who underwent emergent splenectomy and presented 1 week later with acute ST segment elevation myocardial infarction. Severe thrombocytosis, which was not present prior to splenectomy, was noted, and a diagnosis of reactive thrombocytosis was initially made. Involvement of the right coronary artery led to emergent percutaneous transluminal coronary angioplasty. Essential thrombocytosis was considered when treatment with hydroxyurea failed to lower the platelet count. A review of arterial and venous thrombosis in patients with severe thrombocytosis is presented, and the approach to the management of such patients is discussed.

In vitro thrombotic tendency of reactive thrombocytosis in critically ill patients: a prospective case-control study

It is uncertain whether reactive thrombocytosis is associated with an increased risk of thrombosis. This prospective case-control study assessed the in vitro thrombotic tendency of patients with reactive thrombocytosis. Forty-eight patients with reactive thrombocytosis, defined by platelet count >500x10(9)/l and 55 similar, randomly selected critically ill patients who did not have reactive thrombocytosis were considered. In vitro thrombotic tendency in both groups of patients was assessed using maximal amplitude (normal range 54 to 72 mm) and alpha angle (normal range 47 to 74°) on the thromboelastograph. The associations between reactive thrombocytosis and C-reactive protein, the coagulation profile and Sequential Organ Failure Assessment score were also evaluated. Patients with reactive thrombocytosis had an associated increased in vitro thrombotic tendency (maximal amplitude 77 vs 69 mm, mean difference 8 mm, 95% confidence interval 4.9 to 10.9, P=0.001), a higher fibrinogen concentration (7.2 vs 5.8 g/l, P=0.003), and a higher incidence of infection requiring antibiotics (50 vs 27%, P=0.025) compared to patients without thrombocytosis. Platelet count had a relatively linear relationship with the maximal amplitude and the alpha angle of the thromboelastograph tracing (Pearson correlation coefficient: 0.53, P=0.001). In the multivariate analysis, only reactive thrombocytosis (odds ratio 5.9, 95% confidence interval 1.3-27.8, P=0.025) and activated partial thromboplastin time (odds ratio 0.93 per second increment, 95% confidence interval 0.87 to 0.99, P=0.016) were significantly associated with a strong in vitro thrombotic tendency. In summary, reactive thrombocytosis was associated with infection requiring antibiotics and evidence of increased in vitro thrombotic tendency in critically ill patients.

An ulceronecrotic foot lesion in a patient with essential thrombocythemia: successful treatment with hydroxyurea

The patient was a 47-year-old woman with a painful ulcer that had appeared on the right 5th toe two weeks before she visited our hospital. Histopathological examination showed that thrombi were present in small blood vessels in the dermis and pancytosis was detected in a blood test, suggesting polycythemia-associated ulceration of the toe. Essential thrombocythemia was diagnosed based on bone marrow puncture and chromosomal test findings. Platelet count and the ulcer were improved by oral hydroxyurea.

Coagulation activation in an experimental pneumonia model in malnourished mice

Malnutrition induces a decrease in immunity that affects the ability of the organism to deal with an infectious challenge. The clotting system is considered a branch of immunity and its activation is important in the pathogenesis of an infectious disease. This work was conducted to determine coagulation modifications in malnourished hosts before and during infection. Weaned mice were malnourished via a protein-free diet. Well-nourished control mice (WNC) consumed a balanced conventional diet. Malnourished mice (MN) and WNC were challenged intranasally with Streptococcus pneumoniae. Blood, bronchoalveolar lavages (BAL), and lung samples were taken at different times post infection. The results were that MN showed altered hemostatic tests and fibrin(ogen) deposits in the lung. Thus, an increase in thrombin-antithrombin complexes (TATc) in plasma and BAL was observed. In the MN group, infection induced a rise in TATc in plasma and BAL and increased plasma fibrinogen and fibrin(ogen) deposits in the lung. A decrease in activated protein C and antithrombin in BAL and an early decrease followed by an increase in plasma Factor VIII were also observed. Thus, malnourishment induced a procoagulant state increased by infection. This is the first work that presents results of an exhaustive study of coagulation in malnourished hosts before and during an infection.

Thrombocytosis: diagnostic evaluation, thrombotic risk stratification, and risk-based management strategies

Thrombocytosis is a commonly encountered clinical scenario, with a large proportion of cases discovered incidentally. The differential diagnosis for thrombocytosis is broad and the diagnostic process can be challenging. Thrombocytosis can be spurious, attributed to a reactive process or due to clonal disorder. This distinction is important as it carries implications for evaluation, prognosis, and treatment. Clonal thrombocytosis associated with the myeloproliferative neoplasms, especially essential thrombocythemia and polycythemia vera, carries a unique prognostic profile, with a markedly increased risk of thrombosis. This risk is the driving factor behind treatment strategies in these disorders. Clinical trials utilizing targeted therapies in thrombocytosis are ongoing with new therapeutic targets waiting to be explored. This paper will outline the mechanisms underlying thrombocytosis, the diagnostic evaluation of thrombocytosis, complications of thrombocytosis with a special focus on thrombotic risk as well as treatment options for clonal processes leading to thrombocytosis, including essential thrombocythemia and polycythemia vera.

How I treat essential thrombocythemia

In the past 5 years we have witnessed significant advances in both the diagnostic process and optimal therapy for patients with essential thrombocythemia (ET). Insights into the underlying molecular mechanisms have been accompanied by the development of new diagnostic tests and by an improved understanding of the relationship between ET and other related myeloproliferative neoplasms, such as polycythemia vera and primary myelofibrosis. In the first part of this review, we describe how recent molecular and histologic studies can be integrated into a streamlined diagnostic process that is applicable to everyday clinical practice. We also address areas of current diagnostic controversy, including heterogeneity within ET and the phenotypic overlap between ET, polycythemia vera, and primary myelofibrosis. In the second part, we provide an overview of our current approach to the treatment of ET, including risk stratification, choice of cytoreductive agent, and a consideration of special situations such as the pregnant or perioperative patient. Areas of controversy discussed include the identification of those at high risk of complications and therapeutic decisions in the younger patient.

Traditional laboratory measures of cardiovascular risk in hereditary spherocytosis

BACKGROUND

Individuals who have undergone splenectomy may be at an increased risk of arterial and venous thrombosis. We sought to determine if splenectomy affects surrogate laboratory measures of cardiovascular risk in persons with hereditary spherocytosis (HS).

PROCEDURE

We conducted a prospective cross-sectional study of 21 children and 36 adults with HS. Fasting blood samples were collected for complete blood count and plasma lipid panel, homocysteine, lipoprotein (a), C-reactive protein, and fibrinogen. The variables were compared between the groups with and without prior splenectomy by Mann-Whitney tests.

RESULTS

Subjects with prior splenectomy had higher hemoglobin, white blood cell and platelet counts and lower reticulocyte counts and total serum bilirubin concentrations (P < 0.001). Subjects not having had splenectomy had lower than normal levels of total and LDL-cholesterol (LDL-C). Total and LDL-C values were significantly higher, as were fibrinogen and homocysteine concentrations, in the post-splenectomy subjects than in individuals with intact spleen.

CONCLUSION

Various lipid levels and other measures of cardiovascular risk are affected by splenectomy in persons with HS. Further investigations are indicated to more clearly define the balance of the potential benefits of hemolysis and anemia versus the deleterious effects of splenectomy in HS.

Systemic thromboembolic complications after laparoscopic splenectomy for idiopathic thrombocytopenic purpura in comparison to open surgery in the absence of anticoagulant prophylaxis

BACKGROUND

Idiopathic thrombocytopenic purpura (ITP) in adults has a chronic course and may necessitate splenectomy. The current study was undertaken to study the systemic thromboembolic complications of laparoscopic splenectomy (LS) versus open splenectomy (OS) in patients with ITP at two large referral hospitals.

PATIENTS AND METHODS

We conducted a retrospective analysis of 49 patients who underwent splenectomy (21 LS and 28 OS) for primary/relapsing refractory ITP between June 1995 and November 2004. Clinically and/or radiologically confirmed deep venous thrombosis (DVT) and/or pulmonary embolism (PE) were assessed within 2 weeks before and after splenectomy. None had prophylactic anticoagulants immediately after surgery. Follow up of those who developed complications continued for at least 2 additional years to assess for contributing factors that may have been masked at the time of occurrence.

RESULTS

Two (9.5%) LS group had acute PE within 5 days of LS and their platelet count reached 500A103/I(1/4)L within 4 days and 1000A103/I(1/4)L within 7 days after surgery. Three conversions to OS occurred; none had VTE. DVT occurred in 3 patients (10.7%) in the OS group; none were life threatening. There were no deaths.

CONCLUSION

Life-threatening venous thromboembolic events are serious complications after LS and OS for ITP patients if prophylactic anticoagulants are not administered. Patients at risk are those who both have an exponential rise of the platelet count, although factors other than the platelet count may be contributing in OS. Postsplenectomy, ITP should be considered as a thrombophilic condition and studies of additional measures to prevent such events are warranted.

Deficiency of 5-hydroxyisourate hydrolase causes hepatomegaly and hepatocellular carcinoma in mice

With the notable exception of humans, uric acid is degraded to (S)-allantoin in a biochemical pathway catalyzed by urate oxidase, 5-hydroxyisourate (HIU) hydrolase, and 2-oxo-4-hydroxy-4-carboxy-5-ureidoimidazoline decarboxylase in most vertebrate species. A point mutation in the gene encoding mouse HIU hydrolase, Urah, that perturbed uric acid metabolism within the liver was discovered during a mutagenesis screen in mice. The predicted substitution of cysteine for tyrosine in a conserved helical region of the mutant-encoded HIU hydrolase resulted in undetectable protein expression. Mice homozygous for this mutation developed elevated platelet counts secondary to excess thrombopoietin production and hepatomegaly. The majority of homozygous mutant mice also developed hepatocellular carcinoma, and tumor development was accelerated by exposure to radiation. The development of hepatomegaly and liver tumors in mice lacking Urah suggests that uric acid metabolites may be toxic and that urate oxidase activity without HIU hydrolase function may affect liver growth and transformation. The absence of HIU hydrolase in humans predicts slowed metabolism of HIU after clinical administration of exogenous urate oxidase in conditions of uric acid-related pathology. The data suggest that prolonged urate oxidase therapy should be combined with careful assessment of toxicity associated with extrahepatic production of uric acid metabolites.

Progressive postinjury thrombocytosis is associated with thromboembolic complications

BACKGROUND

Our previous investigation demonstrated that despite routine chemoprophylaxis, thrombelastography, which is a comprehensive test measuring the viscoelastic properties of blood, identified a hypercoagulable state in a cohort of critically ill surgical patients that was associated with thromboemobolic events. Furthermore, because thrombelastography allows for the comprehensive assessment of coagulation status, this work suggested that platelet hyperactivity is a component of the hypercoagulable state. We hypothesized that progressive postinjury thrombocytosis contributes to a hypercoagulable state that is associated with thrombelastography.

METHODS

One thousand four hundred and forty severely injured patients surviving >48 h were entered into a database prospectively over 12 years. The variables that were evaluated in associated with thrombocytosis (platelet count >450,000) included age, Injury Severity Score, packed red blood cell transfusions in 12 h, and thromboemobolic complications (TE) (deep venous thrombosis, pulmonary embolus, mesenteric thrombosis, stroke, and arterial thrombosis). The time frame for the development of thrombocytosis was assessed at greater or less than 7 days postinjury. Logistic regression was used to identify the independent variables predictive of thrombocytosis and to adjust the association of thrombocytosis with TE for other risk factors. C-statistic was used to assess the discriminative power of thrombocytosis for prediction of TE.

RESULTS

The mean age was 37.4 ± 0.4 years. The Injury Severity Score was 29.3 ± 0.3, and mean red blood cell transfusions in 12 h was 4.4 ± 0.2 units. Injury via blunt force occurred in 76% of patients, and 72% of patients were male. Thrombocytosis was identified in 447 (31%) patients and was noted almost exclusively >7 days postinjury (98%). TE developed in 35 (8%) of the 447 patients with thrombocytosis, compared with 45 (4.5%) of the remaining 993 patients who did not develop thrombocytosis. Persistent thrombocytosis >7 days was associated with TE (P > .0001). Logistic regression analysis indicated that when adjusted for intensive care unit duration of stay, transfusions, age, and Injury Severity Score, patients with sustained thrombocytosis more than 3 days were noted to have a 1.4 × increased risk of TE (odds ratio, 1.12; 95% confidence interval, 1.04-1.2; P = .002; C-statistic = 0.82).

CONCLUSION

Persistent thrombocytosis in critically injured patients receiving routine chemoprophylaxis is associated with thrombotic complications. Subsequent investigation is warranted to differentiate enzymatic from platelet hypercoagulability to ascertain the role of antiplatelet therapy for prevention of TE.

Haemotoxicity of busulphan, doxorubicin, cisplatin and cyclophosphamide in the female BALB/c mouse using a brief regimen of drug administration

Many anticancer drugs are myelotoxic and cause bone marrow depression; however, generally, the marrow/blood returns to normal after treatment. Nevertheless, after the administration of some anti-neoplastic agents (e.g. busulphan, BU) under conditions as yet undefined, the marrow may begin a return towards normal, but normality may not be achieved, and late-stage/residual marrow injury may be evident. The present studies were conducted to develop a short-term mouse model (a 'screen') to identify late-stage/residual marrow injury using a brief regimen of drug administration. Female BALB/c mice were treated with BU, doxorubicin (DOX), cisplatin (CISPLAT) or cyclophosphamide (CYCLOPHOS) on days 1, 3 and 5. In 'preliminary studies', a maximum tolerated dose (MTD) for each drug was determined for use in 'main studies'. In main studies, mice were treated with vehicle (control), low and high (the MTD) dose levels of each agent. Necropsies were performed, and blood parameters and femoral/humeral nucleated marrow cell counts (FNCC/HNCC) were assessed on six occasions (from days 1 to 60/61 post-dosing). Late-stage/residual changes were apparent in BU-treated mice at day 61 post-dosing: RBC, Hb and haematocrit were reduced, mean cell volume/mean cell haemoglobin were increased and platelet and FNCC counts were decreased. Mice given DOX, CISPLAT and CYCLOPHOS, in general, showed no clear late-stage/residual effects (day 60/61). It was concluded that a brief regimen of drug administration, at an MTD, with assessment at day 60/61 post-dosing was a suitable short-term method/screen in the mouse for detecting late-stage/residual marrow injury for BU, a drug shown to exhibit these effects in man.

Platelet counts in adults with iron deficiency anemia

In adults with iron deficiency anemia (IDA), abnormal platelet counts were seen in several studies. However we retrospectively examined the clinical records of a larger number of adults with IDA to assess abnormal platelet counts. From November 2006 to April 2008, 615 consecutive adults (73 men and 542 women; age range, 16-88 years) with IDA were included in this study. The mean initial hemoglobin was 9.0 +/- 1.8 g/dL (range 2.7-12.8 g/dL), and the mean initial platelet count was 304 x 10(3)/microL +/- 92.3 (range, 105-700 x 10(3)/microL). The initial platelet counts were normal in 520 (84.6%) adults with IDA. Thrombocytosis (>400 x 10(3)/microL) and thrombocytopenia (<150 x 10(3)/microL) were detected in 82 (13.3%) and 13 (2.1%) adults with IDA, respectively. In conclusion, thrombocytosis was seen at lower rates in our study. Furthermore, this study shows that mild thrombocytopenia is not so rare in adults with IDA.

Influence of asymptomatic pneumonia on the response to hemorrhage and resuscitation in swine

INTRODUCTION

Investigation of resuscitation fluids in our swine hemorrhage model revealed moderate to severe chronic pneumonia in five swine at necropsy. Our veterinary staff suggested that we perform a retrospective analysis of prospectively collected data from these animals. We compared the data to that of ten healthy swine to determine the physiologic consequences of the added stress on our hemorrhage/resuscitation model.

METHODS

Anesthetized, immature female swine (40 ± 5 kg) were instrumented for determining arterial and venous pressures, cardiac output and urine production. A controlled hemorrhage of 20 ml/kg over 4 min 40 sec was followed at 30 min by a second hemorrhage of 8 ml/kg and resuscitation with 1.5 ml/kg/min of LR solutions to achieve and maintain systolic blood pressure at 80 ± 5 mmHg for 3.5 hrs. Chemistries and arterial and venous blood gasses were determined from periodic blood samples along with hemodynamic variables.

RESULTS

There were significant decreases in survival, urine output, cardiac output and oxygen delivery at 60 min and O2 consumption at 120 min in the pneumonia group compared to the non-pneumonia group. There were no differences in other metabolic or hemodynamic data between the groups.

CONCLUSION

Although pneumonia had little influence on pulmonary gas exchange, it influenced cardiac output, urine output and survival compared to healthy swine, suggesting a decrease in the physiologic reserve. These data may be relevant to patients with subclinical infection who are stressed by hemorrhage and may explain in part why some similarly injured patients require more resuscitation efforts than others.

Recommended timing for surveillance ultrasonography to diagnose portal splenic vein thrombosis after laparoscopic splenectomy

BACKGROUND

Symptomatic portal or splenic vein thrombosis (PSVT) is a rare but potentially lethal complication of laparoscopic splenectomy (LS). While routine postoperative duplex ultrasound surveillance can be used for early detection, the optimal timing is unknown. The aim of this study is to investigate the incidence and progression of asymptomatic PSVT 1 week and 1 month after LS.

METHODS

Consecutive patients scheduled for LS for hematologic disease participated in this study. Patients underwent surveillance for PSVT using duplex ultrasonography 1 week and 1 month postoperatively.

RESULTS

43 of 48 patients planning to undergo LS in the study period were enrolled, with 3 subsequently excluded, leaving 40 for further analysis. The indications for LS were benign disease in 31 [19 had immune thrombocytopenia purpura (ITP)] and malignant disease in 9. A hand-assisted technique was used in 12 cases. PSVT was diagnosed in 9/40 patients (22.5%). Seven (77.8%) were diagnosed by 1 week with ultrasound, of whom one had mild symptoms (fever and diarrhea). After anticoagulation, subsequent ultrasounds showed resolution or improvement in all seven patients. Thirty-three patients had a normal ultrasound result at 1 week. One of these patients also had a computed tomography (CT) scan that found a PSVT not seen on ultrasound. Twenty-seven patients returned for follow-up after normal 1-week imaging: 26 patients had an ultrasound at 1 month, with no new PSVT found. One additional patient did not return for subsequent ultrasound until 2 months later, when a new distal SVT was found; ultrasound at 6 months showed complete resolution without treatment.

CONCLUSION

The 1-week incidence of PSVT after LS was 8/40 (20%). The high incidence justifies ultrasonographic screening on postoperative day 7. If asymptomatic PSVT has not developed at this time, it is unlikely to develop by 1 month, and subsequent screening ultrasound at 1 month is not required.

Extreme Thrombocytosis in Trauma Patients: Are Antiplatelet Agents the Answer?

The purpose of this study was to review the incidence of extreme thrombocytosis (ExT) (platelet count 1,000,000/μL or greater) in trauma patients and to examine the role of antiplatelet agents in its treatment. The Los Angeles County Medical Center trauma registry was used to obtain injury demographics, medications, and daily platelet counts for injured patients 16 years of age or older admitted between July 2005 and February 2008. Of 6,985 total trauma patients admitted during the study period, 95 developed ExT (1.4%). Average age was 29 years (range, 16-63 years), 89 per cent were male, 44 per cent had penetrating trauma, and mean Injury Severity Score was 24 (range, 1-57). Of the 95 patients with ExT, 41 were treated with aspirin (43%) and 54 were not (57%). The two groups did not differ with regard to basic demographics, injury patterns, vitals on admission, or splenectomy rate (34 vs 20%, P = 0.13). After adjusting for maximum platelet counts and duration of ExT, there was no difference between the treated and untreated groups in terms of mortality, complications, and intensive care unit or hospital lengths of stay. The incidence of ExT is approximately 1.4 per cent in trauma patients. Antiplatelet therapy does not affect ExT patient outcome. Further prospective studies are warranted.

Class prediction models of thrombocytosis using genetic biomarkers

Criteria for distinguishing among etiologies of thrombocytosis are limited in their capacity to delineate clonal (essential thrombocythemia [ET]) from nonclonal (reactive thrombocytosis [RT]) etiologies. We studied platelet transcript profiles of 126 subjects (48 controls, 38 RT, 40 ET [24 contained the JAK2V(617)F mutation]) to identify transcript subsets that segregated phenotypes. Cross-platform consistency was validated using quantitative real-time polymerase chain reaction (RT-PCR). Class prediction algorithms were developed to assign phenotypic class between the thrombocytosis cohorts, and by JAK2 genotype. Sex differences were rare in normal and ET cohorts (< 1% of genes) but were male-skewed for approximately 3% of RT genes. An 11-biomarker gene subset using the microarray data discriminated among the 3 cohorts with 86.3% accuracy, with 93.6% accuracy in 2-way class prediction (ET vs RT). Subsequent quantitative RT-PCR analysis established that these biomarkers were 87.1% accurate in prospective classification of a new cohort. A 4-biomarker gene subset predicted JAK2 wild-type ET in more than 85% patient samples using either microarray or RT-PCR profiling, with lower predictive capacity in JAK2V(617)F mutant ET patients. These results establish that distinct genetic biomarker subsets can predict thrombocytosis class using routine phlebotomy.

Postoperative thrombocytosis as a marker for complications after urologic surgery

OBJECTIVE

To determine whether thrombocytosis after urologic surgery is a random phenomenon or if it is related to postoperative complications.

MATERIAL AND METHODS

We evaluated the postoperative course of patients who had a normal platelet count before surgery and developed significant thrombocytosis (platelet count> 500 x 10(9)/l) after surgery during the years 1991-2003. The rate of postoperative complications was compared among patients who did and did not develop thrombocytosis for the three commonest surgical procedures associated with the condition (radical cystectomy, percutaneous nephrolithotripsy and nephrectomy).

RESULTS

A total of 179 patients developed thrombocytosis (mean+/-SD platelet count 580+/-105 x 10(9)/l; range 501-1,390 x 10(9)/l) after a mean of 13.6 days (SD 14.7 days) following surgery. In 90% of these patients, postoperative complications were diagnosed. The most frequent complications were as follows: urosepsis, n = 49 (27%); hemorrhage, n = 37 (21%); and thromboembolism, n = 15 (8.4%). These complications were diagnosed by means of clinical examination in 114 cases (64%), CT in 31 (17%), Doppler ultrasound in seven (4%) and other diagnostic modalities in nine. In 18 patients (10%), no apparent complication was diagnosed. The rate of postoperative complications was significantly higher among patients who developed thrombocytosis after surgery compared to those who did not (p < 0.00001). In 63 patients (35%), the finding of thrombocytosis preceded the diagnosis of the complication (by a median period of 5 days). In these patients, thrombocytosis was essentially an early marker for the impending complication.

CONCLUSIONS

Postoperative thrombocytosis is not a random phenomenon. It is a serious sign that should not be ignored. Septic and thromboembolic complications should be actively sought by means of thorough clinical evaluation. CT of the abdomen should be considered in appropriate clinical settings. The timing of thrombocytosis and the pathologic spectrum of diseases demonstrated by patients with it justify classifying it as a marker of the subacute phase.

The role of the Platelet Function Analyzer (PFA)-100 and platelet aggregometry in the differentiation of essential thrombocythemia from reactive thrombocytosis

INTRODUCTION

The most crucial component of all diagnostic criteria for essential thrombocythemia (ET) has been the exclusion of reactive thrombocytosis (RT). Our aim was to evaluate the diagnostic performance of the PFA-100 collagen-epinephrine (CEPI) cartridge test and epinephrine-induced aggregometry individually, but mainly combined, in the differentiation of ET from RT.

MATERIALS AND METHODS

26 patients with ET and 25 with RT were studied. Platelet function was analyzed by the PFA-100 and by light transmission aggregometry with epinephrine and ADP. The JAK2 mutational status was identified and hematological parameters, plasma von Willebrand factor antigen and activity levels were also assessed.

RESULTS

The sensitivity (Se), specificity (Sp), positive predictive value (PPV), and the negative predictive value (NPV) of PFA-100 CEPI vs epinephrine-induced aggregometry in the differentiation of ET from RT were estimated as follows: Se (%): 78.9 vs 84.6, Sp (%): 92.0 vs 96.0, PPV (%): 88.2 vs 95.7, NPV (%): 85.2 vs 85.7, respectively. When both of these methods were combined, a lower sensitivity of 68.4%, but a specificity of 100% was attained. The PPV observed with this double abnormal combination was 100% and the NPV 80.6%. Lastly, when we assessed the abnormality for either CEPI CT or epinephrine-induced aggregometry, the sensitivity was 100%, the specificity 88.0%, PPV 86.4% and NPV 100%. Thus, an abnormal combination was strongly suggestive of ET, while normal results with both methods excluded ET.

CONCLUSIONS

If our results are replicated by further studies, these two methods could be used very effectively as adjunct markers in the differentiation between ET and RT.

Helicobacter pylorieradication reduces platelet count in patients without idiopathic thrombocytopenic purpura

Discrepant outcomes of Helicobacter pylori eradication in patients with idiopathic thrombocytopenic purpura have been reported. Here patients with dyspepsia and no other complications underwent gastroendoscopic examination and evaluation for Helicobacter pylori infection. Helicobacter pylori-infected patients with gastritis and gastric ulcer received eradication therapy: lansoprazole (60 mg/day), clarithromycin (400 mg/day), and amoxicillin (1500 mg/day) for 1 week. Lansoprazole 30 mg/day was administrated additional 7 weeks. Peripheral platelets were counted before treatment, 8 weeks after initiation of therapy, and at follow-up periods. Platelet counts in patients with both gastritis and gastric ulcer were evaluated with reference to the presence of Helicobacter pylori infection. Eighty-seven patients with gastritis and 35 of those with gastric ulcer underwent successful eradication therapy. Peripheral platelet counts in patients with gastritis decreased from 235+/-55 to 228+/-58 (10(3)/microL) (p=0.0337), and those with gastric ulcer decreased from 248+/-60 to 232+/-48 (10(3)/microL) (p=0.020) 8 weeks after initiation of therapy. Non-eradicated patients did not show such a tendency. Helicobacter pylori eradication reduced peripheral platelet counts in patients with gastritis and gastric ulcer. Amelioration of thrombocytopenia by eradicating Helicobacter pylori appears to involve mechanisms specific to idiopathic thrombocytopenic purpura.

Augmentation of Megakaryocyte Expression of FcγRIIa by Interferon γ

Objective— The purpose of this study was to identify factors that alter expression of FcγRIIa by megakaryocytes.

Methods and Results— Effects of selected cytokines and growth factors on megakaryocyte expression of FcγRIIa were assessed with phorbol 12-myristate 13-acetate (PMA)-differentiated human erythroleukemia (HEL) cells and with thrombopoietin-differentiated CD34 stem cells and compared with those obtained with myelocytic cell lines and a monocytic cell lines. Expression of FcγRIIa was quantified with the use of Western blots and real-time reverse transcriptase-polymerase chain reaction. Megakaryocyte differentiation was identified by expression of CD41, CD42, and von Willebrand factor with the use of flow cytometry. Interferon (IFN) γ increased protein expression of FcγRIIa by HEL cells and CD34 stem cells after megakaryocyte differentiation (maximal ≈4-fold, P <0.001 for each). IFNγ did not increase expression of FcγRIIa by undifferentiated HEL and CD34 cells. Expression of FcγRIIa mRNA was increased (2-fold, P <0.001) in megakaryocyte-differentiated HEL cells. IFNγ did not increase expression of FcγRIIa by undifferentiated myelocytic or monocytic cell lines.

Conclusions— IFNγ appears to selectively increase expression of FcγRIIa by cells exhibiting characteristics of megakaryocytes. This effect of IFNγ may contribute to greater platelet expression of FcγRIIa in patients with atherosclerotic vascular disease.

What is the significance of thrombocytosis in patients with trauma?

BACKGROUND

The incidence and risk factors for the development of thrombocytosis after trauma have not been well established. Although it has been suggested that the occurrence of this sequela may be associated with adverse events, there are also limited data regarding outcomes of patients developing posttraumatic thrombocytosis. The objective of this study was to determine the incidence of, risk factors for, and sequela of posttraumatic thrombocytosis.

METHODS

A retrospective review of all trauma intensive care unit (ICU) admissions between July 1998 and December 2005 identified patients with early (< or = 7 days), late, and no thrombocytosis. Bivariate analysis was used to compare the clinical and demographic characteristics with outcomes between the three patient groups.

RESULTS

A total of 3,484 patients were admitted to the ICU during the 7-year study period. After exclusions, the study population consisted of 3,286 patients. The overall incidence of thrombocytosis was 18.7%; early thrombocytosis was found in 72 patients, and late thrombocytosis was identified in 542 patients. All complications examined were significantly higher in patients with thrombocytosis. Overall, the venous thromboembolic rate was 2.4%; for patients with thrombocytosis it was 4.6% compared with 1.9% in patients without thrombocytosis. Overall mortality was 15.4%, but was significantly lower in patients with thrombocytosis (3.8% vs. 18.1%, p < 0.0001). Independent risk factors for the development of thrombocytosis included obesity, laparotomy, blunt injury, Injury Severity Score > 16, mechanical ventilation, Chest Abbreviated Injury Score > 3, and tachycardia.

CONCLUSION

Thrombocytosis is a common finding among patients with trauma admitted to the ICU. The occurrence of both early and late thrombocytosis is associated with significantly higher rates of complications, particularly venous thromboembolism. However, patients developing posttraumatic thrombocytosis may have a significantly lower mortality compared with those without this sequela of injury.

[Severe perioperative thrombocytosis in a patient undergoing lung resection]

Severe thrombocytosis (platelet count > 1,000,000 microL(-1)) is a rare, usually reactive, process and few perioperative cases have been reported. We describe the management of a patient who developed severe reactive thrombocytosis in the preoperative period before undergoing segmentectomy to remove a malignant nodule. A platelet count of 2,086,000 microL(-1) was observed during the first few days after surgery; we therefore started antiplatelet therapy to prevent thrombotic complications. We analyze the factors that might have contributed to the development of severe thrombocytosis in this case and discuss the different treatment options that may affect perioperative outcomes in these patients.

Platelet count and the risk for thrombosis and death in the elderly

AIM

Our aim was to examine the association between platelet count and the incidence of myocardial infarction, ischemic stroke, hemorrhagic stroke, venous thrombosis, and mortality.

METHODS AND RESULTS

Platelet count was measured at baseline in 1989-1990 and at 3 years follow-up, or at baseline (for a newly recruited group) in 1992-1993 in 5766 community-dwelling individuals aged 65 years and older (mean age at baseline, 73 years). During 12-15 years of follow-up, there were 821 incident myocardial infarctions, 807 ischemic strokes, 161 hemorrhagic strokes, 159 venous thrombotic events, and 3413 participants died. Platelet count was not associated with the occurrence of myocardial infarction, ischemic or hemorrhagic stroke, venous thrombosis, or cardiovascular mortality. Non-cardiovascular mortality was higher among both participants with low and with high platelet count. Adjusted non-cardiovascular mortality rates for platelet counts below 100, 100-199, 300-399, and above 400 x 10(9) L(-1) relative to the reference mortality rate in participants with platelet count values between 200 and 299 x 10(9) L(-1) were 1.89 (1.21-2.96), 1.08 (0.98-1.20), 1.20 (1.06-1.37), and 1.47 (1.14-1.90), respectively.

CONCLUSION

Platelet counts were not associated with vascular outcomes but low and high platelet counts were associated with non-cardiovascular mortality, including cancer mortality.

Thrombocytosis

Major progress in understanding the pathogenesis in patients with thrombocytosis has been made by identifying mutations in the key regulators of thrombopoietin: the thrombopoietin receptor MPL and JAK2. Together, these mutations can be found in 50% to 60% of patients with essential thrombocythemia or primary myelofibrosis and in 10% to 20% of hereditary thrombocytosis. A decrease in expression of the Mpl protein can cause thrombocytosis even in the absence of mutations in the coding sequence, due to a shift in the balance between stimulation of signaling in megakaryopoiesis and removal of thrombopoietin by receptor mediated internalization in platelets. When present in a heterozygous state the JAK2-V617F mutation preferentially stimulates megakaryopoiesis and in most cases manifests as essential thrombocythemia (ET), whereas homozygous JAK2-V617F reduces megakaryopoiesis in favor of increased erythropoiesis, resulting in polycythemia vera and/or myelofibrosis. In 30% to 40% of patients with ET or primary myelofibrosis (PMF) and in 80% to 90% of pedigrees with hereditary thrombocytosis the disease-causing gene remains unknown. Ongoing genetic and genomic screens have identified genes that, when mutated, can cause thrombocytosis in mouse models. A more complete picture of the pathways that regulate megakaryopoisis and platelet production will be important for finding new ways of controlling platelet production in patients with thrombocytosis.

Preoperative platelet count and survival prognosis in resected pancreatic ductal adenocarcinoma

BACKGROUND

High platelet counts are associated with an adverse effect on survival in various neoplastic entities. The prognostic relevance of preoperative platelet count in pancreatic cancer has not been clarified.

METHODS

We performed a retrospective review of 205 patients with ductal adenocarcinoma who underwent surgical resection between 1990 and 2003. Demographic, surgical, and clinicopathologic variables were collected. A cutoff of 300,000/mul was used to define high platelet count.

RESULTS

Of the 205 patients, 56 (27.4%) had a high platelet count, whereas 149 patients (72.6%) comprised the low platelet group. The overall median survival was 17 (2-178) months. The median survival of the high platelet group was 18 (2-137) months, and that of the low platelet group was 15 (2-178) months (p = 0.7). On multivariate analysis, lymph node metastasis, vascular invasion, positive margins, and CA 19-9 > 200 U/ml were all significantly associated with poor survival.

CONCLUSIONS

There is no evidence to support preoperative platelet count as either an adverse or favorable prognostic factor in pancreatic ductal adenocarcinoma. Use of 5-year actual survival data confirms that lymph node metastases, positive margins, vascular invasion, and CA 19-9 are predictors of poor survival in resected pancreatic cancer.

Complications of splenectomy

Surgical removal of the spleen, splenectomy, is a procedure that has significantly decreased in frequency as our understanding of the infectious complications of the asplenic state increased. The full spectrum and details of splenic function, however, have yet to be fully outlined. As a result, our comprehension of the long-term consequences of splenectomy remains incomplete. We review the evidence relating to the effects of splenectomy on infection, malignancy, thrombosis, and transplantation. Perhaps the best-defined and most widely understood complication of splenectomy is the asplenic patient's susceptibility to infection. In response to this concern, novel techniques have emerged to attempt to preserve splenic function in those patients for whom surgical therapy of the spleen is necessary. The efficacy of these techniques in preserving splenic function and staving off the complications associated with splenectomy is also reviewed in this article.

STAT1 promotes megakaryopoiesis downstream of GATA-1 in mice

Thrombocytosis is associated with inflammation, and certain inflammatory cytokines, including IFN-gamma, stimulate megakaryocyte and platelet production. However, the roles of IFN-gamma and its downstream effector STAT1 in megakaryocyte development are poorly understood. We previously reported that STAT1 expression was significantly downregulated in Gata1-knockdown murine megakaryocytes, which also have impaired terminal maturation. Here, we show that ectopic expression of STAT1, or its target effector IRF-1, rescued multiple defects in Gata1-deficient megakaryopoiesis in mice, inducing polyploidization and expression of a subset of platelet-expressing genes. Enforced expression of STAT1, IRF-1, or GATA-1 enhanced phosphorylation of STAT1, STAT3, and STAT5 in cultured Gata1-deficient murine megakaryocytes, with concomitant megakaryocyte maturation. In contrast, enhanced thrombopoietin signaling, conferred by enforced expression of constitutively active JAK2 or c-MPL, induced phosphorylation of STAT3 and STAT5, but not STAT1, and failed to rescue megakaryocyte maturation. Finally, megakaryocytes from Stat1(-/-) mice were defective in polyploidization. Together, these findings reveal a unique role for STAT1 in megakaryopoiesis and provide new insights into how GATA-1 regulates this process. Our studies elucidate potential mechanisms by which various inflammatory disorders can cause elevated platelet counts.

Extreme thrombocytosis--an unusual presentation of inflammatory bowel disease

Thrombocytosis or a high platelet count (a count greater than 400 x 10(9)/L) is a common observation especially with the increased ordering of routine complete blood counts. When found, it may create a diagnostic challenge as transient elevations in platelet counts can occur for a number of reasons such as inflammation or infection, and these usually resolve spontaneously; but an elevated platelet count may be the only indication of an underlying serious disease to which no other clinical findings pertain. The report details a case of extreme thrombocytosis which masked an underlying diagnosis of inflammatory bowel disease.

Ischemic stroke and peripheral arterial thromboembolism in a patient with Crohn's disease: a case presentation

Both ischemic stroke and peripheral arterial thromboembolism have been described as extraintestinal complications of inflammatory bowel disease. Here, we present the first case with direct cooccurrence of ischemic stroke and peripheral thromboembolism in a 39-year-old patient with Crohn's disease. A pathophysiological model explaining this cooccurrence as well as the significance of prothrombotic risk factors ("hypercoaguable state") in the setting of inflammatory bowel disease and stroke are discussed.

Portal Vein Thrombosis After Laparoscopic Splenectomy in Benign Hematologic Diseases

INTRODUCTION

Portal vein thrombosis is an unfrequent, but potentially deadly, complication of the laparoscopic splenectomy procedure. The laparoscopic approach has shortened the duration of hospital stay; portal vein thrombosis may appear after the patient has left the hospital, determining a later diagnosis. Because of the mild, nonspecific symptoms, the diagnosis can even be missed and only achieved when chronic complications take place.

OBJECTIVES

In this study, we aimed to determine the appearance of portal vein thrombosis in a consecutive series of patients who underwent laparoscopic splenectomy by performing a contrast-enhanced computed tomography (CT) scan postoperatively.

MATERIALS AND METHODS

A transversal study was established, performing in 2005 a contrast-enhanced CT scan on 20 patients who underwent laparoscopic splenectomy between 1999 and 2005 at Ramón y Cajal University Hospital (Madrid, Spain). The presence of thrombosis in the splenoportomesenteric axis was investigated.

RESULTS

Two (2) cases (10%) of portal vein thrombosis were detected: 1 symptomatic case, 7 days after surgery, was treated with anticoagulation, resulting in the disappearance of the thrombus in a new CT scan 6 months later; the second case was asymptomatic and was discovered during the performance of this study.

CONCLUSIONS

The contrast-enhanced CT scan shows the best accuracy for the diagnosis of portal vein thrombosis, and it must be performed when any clinical manifestation appear; also, it must still be determined if a contrast-enhanced CT scan should be systematically performed in high-risk thromboembolic patients. An ultrasound Doppler may present many diagnostic errors. It is probably advisable to prolong the antithromboembolic prophylaxis.

Gamma-Glutamyltransferase Activity and Total Antioxidant Status in Serum and Platelets of Patients with Community-acquired Pneumonia

BACKGROUND

We undertook this study to analyze serum and platelet gamma-glutamyltransferase (GGT) activity and total antioxidant status (TAS) concentration during the course of pneumonia and to compare them between patients with normal platelet count and those who developed reactive thrombocytosis.

METHODS

Platelet count, GGT activity and TAS concentration in serum (S) and platelet (Plt) isolates were measured in 60 patients with community-acquired pneumonia (CAP) on admission and at discharge.

RESULTS

At the end of treatment, platelet count increased significantly from the value recorded on admission. By the end of treatment, 42% of patients developed reactive thrombocytosis. Serum and platelet GGT activity was higher, whereas (S)TAS was significantly lower in CAP patients than in control subjects. On admission, (Plt)TAS was significantly higher in CAP patients as compared with control subjects; at discharge, (Plt)TAS was lower in comparison with either patient admission and control subjects. GGT activity and TAS concentration in serum and platelet isolate on admission did not differ significantly between patients with and without thrombocytosis. At discharge, (S)GGT activity showed no significant changes, whereas (Plt)GGT decreased significantly in patients with thrombocytosis as compared with those without thrombocytosis. In patients with thrombocytosis, (S)TAS concentration showed no significant difference, whereas (Plt)TAS concentration measured at discharge was significantly lower in patients with thrombocytosis as compared to those with normal platelet count.

CONCLUSIONS

The pattern of changes in (Plt)GGT catalytic activity and TAS concentration might be indicative of a certain role of thrombocytosis during treatment in patients with CAP. Further investigations are necessary to clarify these changes.