Mean platelet volume in acute appendicitis: A gender difference

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Corrigendum

To the editor,

Mean platelet volume (MPV) is an index of platelet production and activation which reflects the changes in platelet size in various conditions [1–8]. Although, MPV is an easily obtainable index from automated hematology analyzers, it has rather been overlooked until its associations with various diseases are continuously being reported recently. MPV is known to be decreased in diseases of acute pancreatitis, ulcerative colitis, rheumatoid arthritis and ankylosing spondylitis [9–11] as well as local inflammatory conditions including acute appendicitis (AA) due to migration and consumption of highly reactive large platelets into sites of inflammation [12]. AA is a common surgical emergency requiring timely intervention while its diagnosis can be elusive [13]. Association between AA and MPV was first suggested by Albayrak and colleagues followed by Lee and Kim also evaluating the MPV in AA, although this platelet index was found unable to discriminate AA and ectopic pregnancy [14], [15]. To compare MPV levels in AA with other acute abdomen with gynecologic backgrounds, such as ectopic pregnancy, the presence of gender difference in MPV levels should be elucidated preferentially. In this study, we planned to investigate MPV levels in AA and perform the further analysis according to gender groups.

From January 2011 to December 2011, at a tertiary-setting teaching hospital in Korea, we evaluated 196 patients diagnosed with AA of their MPV value. Individuals who visited for medical check-ups were reviewed of their medical charts to exclude history of diabetes, hypertension or smoking, enrolling 143 individuals as control group. Complete blood count results at the time of their arrival to the emergency department were obtained, which were analyzed by Advia 2120 (Siemens Healthcare Diagnostics Inc., Tarrytown, NY). All samples were analyzed within 2 hours using EDTA containing vacutainer bottles, obtained by venipuncture. Through laparoscopic appendectomy and also appendectomy in some cases, specimens were obtained for histopathological examination. Patients were retrospectively reviewed of their medical records and only those with confirmed histopathological results as AA were included. Histopathological results of obtained specimens were mostly acute suppurative appendicitis (84.7%). Thirty cases of acute suppurative appendicitis with perforation (14.8%) and two cases of acute exudative appendicitis (0.5%) were also included. Statistical analyses were done using MedCalc v11.6 (MedCalc Software, Mariakerke, Belgium) and Excel 2007 (Microsoft Corporation, Redmond, WA). Independent sample t-test was used to compare the differences of two groups.

From the comparison of 196 AA patients to 143 healthy controls, laboratory indices compared and characteristics of each group are described in Table I. The mean value of MPV in AA was 7.82 ± 0.64 fL, being significantly lower than 7.96 ± 0.58 fL of healthy controls (p = 0.042). It was a concordant result with the previous reports [14], [15]. It was intriguing to find that when groups were subdivided according to the gender, only the male group showed a statistically significant decrease in MPV (p = 0.009) while the female group did not (Figure 1).

Figure 1. MPV in AA compared to control group according to gender groups. The mean of MPV was significantly lower in male patient group (A) n = 104 than female patient group (B) n = 91, p = 0.009).

Table I. Characteristics of study group of AA and healthy control group.

	AA (mean ± SD)	Control (mean ± SD)
Total number of patients	196	143
Age (years)	41.82 ± 15.53	44.00 ± 10.37
Sex	104:92	72:71
WBC (×10^9/L)	13.05 ± 4.40	5.98 ± 1.69
Neutrophil (%)	78.94 ± 9.63	55.06 ± 8.19
PLT (×10^9/L)	248.20 ± 65.39	257.96 ± 49.24
MPV (fL)	7.82 ± 0.64	7.96 ± 0.58

Abbreviation; SD, standard deviation; WBC, white blood cell; PLT, platelet.

Gasparyan et al. [16] suggested two possible mechanisms of decreased MPV in high-grade inflammatory conditions. First is the overproduction of pro-inflammatory cytokines and acute-phase reactants interfering with megakaryopoiesis which in turn results in subsequent release of small size platelets from the bone marrow. Second is the decreased size of circulating platelets resulting from intensive consumption of larger-sized platelets at sites of inflammation. Although MPV is an index of platelet production and differed among the two compared groups, the platelet count did not differ statistically. Underlying mechanism beneath this finding is yet clearly defined. Resemblance to a previous report by our group [2], which discovered a gender difference of MPV in Korean acute ischemic stroke patients, this study also showed that decline of MPV in AA might be different according to gender, greater in male group. Therefore, we carefully suggest that clinical utility of MPV to discriminate AA from other acute abdomen have to be analyzed separately among genders. In midst of clinical confusion to diagnose AA in difficult cases, further investigation would make MPV a useful laboratory assistance for diagnosing AA.

Conflict of interest

The authors report no conflicts of interest.

This research was supported by a grant from Kyung Hee University in 2012 (KHU-20121736).