To the Editor,

We thank Dr. Karabulut for his interest in our article entitled “Are mean platelet volume (MPV) and platelet distribution width (PDW) useful parameters in children with acute rheumatic fever (ARF)” regarding the retrospective evaluation of platelet indices, MPV and PDW as a useful marker of platelet activation and severity of inflammation before and after the treatment of ARF [1]. We agree with his opinion about the change in MPV due to the time interval between collection of blood samples and analysis. In our institution, all complete blood count samples are collected in standard ethylenediaminetetraacetic acid (EDTA) tubes and analyzed within 30 min. Although MPV increases until 120 min in EDTA, we do not think that this time interval (30 min) could change the MPV values in our study group. The other comment was regarding our control group; he stated that some factors such as smoking status and city altitude could affect the MPV [3]. In a study cited by Dr. Karabulut, which evaluated the effects of smoking on platelet volume, Varol et al. [2] reported that MPV was positively correlated with age, cigarettes smoked per day and smoking period. Because of the pediatric age of our study and control subjects, long-term regular smoking was less likely. And also our city (Izmir) is in sea level, and our all subjects that were enrolled into this study live in the same altitude. Thus, we think that these variables could not change our results. We only agree with that retrospective design of our study is major limitation of our study, and prospective studies are needed to evaluate the platelet indices in patients with ARF.