EXG-09632; No of Pages 2 Experimental Gerontology xxx (2015) xxx–xxx

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Letter to the editor Effect of age on mean platelet volume: Does it exist?

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With interest we have read the recent paper by Verdoia and colleagues on their study of mean platelet volume (MPV) in patients undergoing coronary angiography (Verdoia et al., 2015). Their main finding is that elderly patients N 75 years old had higher MPV values, although this was not associated with coronary artery disease. This finding was based on linear regression between MPV and age. The correlation was relatively weak (r = 0.08), but statistically significant (Verdoia et al., 2015). This paper stimulated us to review the data from a large study in the general population that we performed previously for establishing reference intervals of reticulated platelets and other platelet parameters (Hoffmann et al., 2013). In short, we measured a complete blood count, including PLT count and MPV in all individuals who attended the “Diagnostiek voor U” Primary Care laboratory during a period of 4 weeks. All blood samples were collected into K2-EDTA evacuated tubes and processed within 6 h using CELL-DYN Sapphire hematology analyzers (Abbott Diagnostics, Santa Clara, CA, USA), following the manufacturer's guidelines. The laboratory's standard operating procedures, including internal and external quality control, were in full accordance with the requirements of CCKL, the Dutch Authority for medical laboratory accreditation. We deleted samples from repeat visits from our database in order to ensure that each individual contributed only a single sample. For statistical examination we used linear regression and analysis of variance (MedCalc version 15.2; MedCalc Software, Oostende, Belgium). Our database included a total of 8089 unique individuals, 5216 females (age range 1–102 years; median 51 years) and 2873 males (age range 0–106 years; median 57 years). Of them, 1471 (18.2%) were older than 75 years, 982 women and 489 men. Linear regression indicated an inverse relationship between MPV and age that was very weak (r = -0.027), yet statistically significant (P = 0.014) as shown in Fig. 1. Further, analysis of variance did not indicate a relationship between MPV and age (P = 0.195) or gender (P = 0.611). Fig. 2 illustrates that MPV is similar across all age classes. Our conclusion is therefore that there are no solid indications for MPV increasing with age. When considering possible explanations for the discrepancy between our findings and those of Verdoia, a number of factors should be mentioned. First of all, our population predominantly included healthy individuals from the general population, while Verdoia studied patients with coronary artery disease. However, we regard it unlikely that this is a relevant factor as in their study MPV was not associated with prevalence or severity of coronary disease (Verdoia et al., 2015) and another study reported that patients with various grades of coronary syndrome had essentially similar MPV as younger, healthy controls

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(Grove et al., 2009). Further, a geographical factor might play a role. The Verdoia study was performed in Novara, northern Italy, and others have reported a progressive increase in MPV with age in Parma, in the same region of northern Italy (Lippi et al., 2012). In contrast, another large Italian study reported no age-related MPV increase in adults (Biino et al., 2012). Then, could analytical factors be involved? MPV is a nonstandardized parameter that is measured by different analytical technologies and it is well known that as a consequence, MPV measured on one hematology analyzer is not identical with MPV from another analyzer (Hoffmann, 2012; Lippi et al., 2015). Verdoia used a Sysmex XE-2100 with impedance technology for measuring MPV (Verdoia et al., 2015), Lippi used a Siemens Advia 2120 with optical technology (Lippi et al., 2012), Biini and colleagues a Beckman Coulter LH analyzer based on impedance principle (Biino et al., 2012), whereas in our present study we used an Abbott CELL-DYN Sapphire, which has dual impedance and optical technology. Despite the differences in technology, which definitely give different absolute values for MPV, we doubt whether age-dependency would be present or absent due to the technology of a given hematology analyzer. A final explanation remaining is that MPV is just an index of thrombopoietic activity. There is little doubt that thrombopoiesis is aimed at keeping an individual's circulating platelet mass constant (Kuter, 2014). This can be done by producing more smaller platelets or fewer larger platelets (Martin et al., 2012); both platelet number in the circulation and platelet size are under strict genetic control (Thon and Italiano, 2012). It is also known that PLT count decreases with age, but remains well within the generally accepted reference interval (Biino et al., 2012; Hoffmann et al., 2013). Also Verdoia and colleagues reported that their elderly patients N 75 years had a significantly lower PLT count than younger patients (Verdoia et al., 2015). In view of the PLT production characteristics pointed out above, this logically implicates that since elderly patients have lower PLT count, their MPV should be higher.

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age (y) Fig. 1. Linear regression of MPV and age; r = −0.027, P = 0.014.

http://dx.doi.org/10.1016/j.exger.2015.06.001 0531-5565/© 2015 Published by Elsevier Inc.

Please cite this article as: Hoffmann, J.J.M.L., et al., Effect of age on mean platelet volume: Does it exist? Exp. Gerontol. (2015), http://dx.doi.org/ 10.1016/j.exger.2015.06.001

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Letter to the editor

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Effect of age on mean platelet volume: Does it exist?

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