Mean platelet volume in patients with acute pancreatitis

J Clin Exp Invest www.clinexpinvest.org Vol 2, No 4, December 2011 Yazışma Adresi /Correspondence: Dr. Nigar Yılmaz Department of Biochemistry, Faculty of Medicine, Mustafa Kemal University, Hatay, Turkey Email: drnigaratilgan@yahoo.com Geliş Tarihi / Received: 03.08.2011, Kabul Tarihi / Accepted: 25.10.2011 Copyright © Klinik ve Deneysel Araştırmalar Dergisi 2011, Her hakkı saklıdır / All rights reserved Klinik ve Deneysel Araştırmalar Dergisi / 2011; 2 (4): 362-365 Journal of Clinical and Experimental Investigations doi: 10.5799/ahinjs.01.2011.04.0072


INTRODUCTION
Acute pancreatitis (AP) is an inflammatory disease characterized by disturbances of pancreatic microcirculation. 1,2The erythrocyte flow patterns and leukocyte-endothelium interaction have role in pathophysiology of AP. 3 Besides, platelet activation plays an important role in damaging of microcirculation in AP.Although platelet activation is implicated in thrombotic diseases, few reports have showed platelet activation in patients with AP.To the best of our knowledge, there are only two studies in the literature about mean platelet volume (MPV) levels in patients with AP4. 5 The platelet function can be assessed easily by MPV which does not require advanced or expensive technology. 6,7In comparison to smaller ones, larger platelets have more granules, aggregate more rapidly with collagen, and release more thromboxane A2 which induces activation of platelets and vasoconstriction. 8It was established that coagulation abnormalities occur in AP and they are related to the severity of the disease. 9However the platelet function and the role of the coagulation cascade in AP remain obscure.The low levels of platelets have been reported to be associated with severity and prognosis of AP. 10 The aim of this study was to investigate the platelet indices including MPV and platelet count in patients with AP.

MATERIALS AND METHODS
The study population consisted of 30 consecutive patients (17 females, 13 males) with AP admitted to Mustafa Kemal University hospital.Thirty subjects matched for age, gender, body mass index (BMI) and frequency of concomitant diseases, that were randomly chosen from the patients admitted to outpatient clinic of general surgery department for other diseases served as controls (15 females, 15 males).There was no significant difference between patients with AP (56.9±20.2years) and control subjects (49.9±15.2years) in terms of the mean age.
Those who did not present any systemic disease and who had normal renal and liver function with no anticoagulant medication history were included in the study.The study was approved by the institutional Ethics Committe of Medical Faculty of Mustafa Kemal University.

Blood sampling
Blood samples were drawn from the antecubital vein by careful vein puncture with a 21 G sterile syringe without stasis at 08.00-10.00AM after a fasting period of 12 h.MPV and platelet counts were measured in blood samples, which were collected to dipotassium EDTA tubes before treatment.Whole blood counts and MPV were determined using an autoanalyzer (Beckman Coulter LH 750).Lipid profiles and amilase were assayed by standard methods (colorimetric method, Beckman Coulter LX-20).CRP was assayed by Beckman Coulter image immunochemistry system.

Statistical analysis
Data were analyzed by using a commercially available statistics software package (SPSS for Win-dows v. 15.0, Chicago, Illinois, USA).Continuous variables from the study groups were reported as mean ± standard deviation, and categorical variables as percentages.Student's-t-test was performed and multiple comparisons were made using least-squares differences.Correlation between different parameters was assessed using Pearson's coefficient test.To compare age, gender, comorbidity diseases, calcium, phosphorus, total protein, albumin, alkaline phosphatase and parathormon, the Student-t-test were used.Results are presented as mean ± SD and p<0.05 was regarded as statistically significant.

RESULTS
The knowledge about clinical features of the study and control groups were summarized in Table 1.There were no statistically significant differences between the two groups with respect to age, gender, BMI, levels of triglyceride, total cholesterol, lowdensity lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL), cholesterol, hemoglobin and white blood cell count (WBC).The level of serum amylase was found significantly increased in patients with AP compared to control group (p<0.001).MPV was significantly higher among AP patients when compared to control group (8.82±1.33 vs. 7.94±0.54fL respectively; p < 0.01).Platelet counts were significantly lower among AP patients when compared to control group (233.0±46.26 vs. 295.3±58.9×109/L respectively; p < 0.001).Platelet counts and MPV were correlated with serum CRP levels (p < 0.01; r = -0.364,r = 0.406 respectively) in correlation analysis.The knowledge about MPV, platelet count and CRP level are shown in Table 2.

DISCUSSION
Recent advances have revealed that platelets contribute to disturbance of the local microcirculation in AP. 11 Activated platelets produce oxygen radicals and proinflammatory mediators including tromboxane A2, platelet factor IV, serotonin, leukotrienes and cause the microvascular disturbances. 12,13The cascade of coagulation events seems to play a critical role in the pathogenesis of AP. 9 It was previously suggested that platelet count is a sensitive parameter for assessing the prognosis in AP. 14 Metabolical and enzymatic activities of larger platelets have previously been shown to be greater than those of smaller platelets.In addition, larger platelets were reported to have higher prothrombotic potential. 15ncreased platelet size is more active in hemostasis, contain more granules and adhesion receptors and release vasoconstrictor mediators.Increased platelet activation leads to activation of coagulation and coagulation affects. 9It was indicated that coagulation, vasoconstriction, inadequate perfusion are significant events in the progression of AP. 16 The platelet function is assessed by MPV which was determined by a simple and easy method.MPV shows the platelet production rate and stimulation. 17In the present study, we analyzed MPV, an indicator of platelet activation in patients with AP.9][20] In consistence with these studies, we also found that MPV was higher in AP patients than in control group.Previous studies have shown that microvascular occlusions can cause platelet activation.Increased platelet activation is well established in Sickle Cell Disease which is characterized by microvascular occlusion.However, decreased MPV was observed in Sickle Cell Disease.Mohan et al. speculated that these MPV may not be a suitable marker of platelet activation in Sickle Cell Anemia. 21In contrast to this study, we found that MPV was elevated in patients with AP.Recently; Abdulla et al. investigated plate-let activation in AP.They showed that platelets play an important role in AP, which is characterized by an impairment of microcirculation due to activation of coagulation and inflammatory cascade systems.Yuksel et al. indicated that decreased MPV may be an indicator for increased diseases activity including ulcerative colitis, crohn's disease, rheumatoid arthritis, ankylosing spondylitis. 20,23,27erefore, increased MPV can be accepted as simple marker of platelet activation in AP.Platelet size is associated with platelet activation, also high MPV level may result of consumption of small platelets and a compensatory production of larger reticulated platelets during AP. 24,28Therefore MPV is preferred using as a marker of platelet activation and platelet function.In this study, platelet count was significantly lower among patients with AP when compared with control group.This lower platelet count in patients with AP might be due to using of the platelets.Assessment of AP severity is routinely done by measuring level of CRP, which is a nonspecific inflammatory marker that is synthesized by the hepatocytes. 25We also found that serum CRP levels were elevated in patients with AP.It has been corrected that an inflammation condition may accompany and possible be related to AP. 31 MPV and platelet counts were correlated with serum CRP level.The increased level of MPV should alert clinicians and warrant early evaluation.It was reported that inflammatory mediators increase platelet production and newly protected platelets found more thrombogenic. 22In previous study, MPV was found associated with high grade inflammation, largely influenced by the intensity of inflammation. 26MPV levels were also shown to be lower in patients with high-grade inflammatory diseases, such as Familial Mediterranean Fever or active Rheumatoid Arthritis.This trend reverses during the course of anti-inflammatory therapy. 20,30V had found no significant direct correlations with serum triglyceride, total cholesterol, LDL cholesterol, HDL cholesterol.Measuring the serum amylase level is helpful in diagnosing AP.However, it was reported that AP is needed a guidelines to be managed. 29MPV may guide to identify high-risk patients in AP and other disturbed microcirculation related disease.MPV may also become a prognostic factor in patients with AP.
In conclusion, we have shown that MPV was significantly elevated in patients with AP and platelet count was decreased in patients with AP.While platelet count shows negative correlation with the level of CRP, which is an inflammatory marker, it shows positive correlation with MPV levels.More

Table 1 .
Comparison of the clinical and laboratory characteristics of the patients with acute pancreatitis and controls.
AP: Acute pancreatitis, F/M: female to male, BMI: body mass index, WBC: white blood cell.pvalue is for comparison between control and study population.JClin Exp Invest www.clinexpinvest.orgVol 2, No 4, December 2011

Table 2 .
Comparison of the platelet indices of the patients with acute pancreatitis and controls.
AP: Acute pancreatitis, MPV: mean platelet volume.a : vs. control group, b : vs. control group, c : vs. control group