Editor,

We read the research study conducted by Zyczkowski et al. [1] related with “Mean platelet volume-to-lymphocyte ratio: a novel biomarker associated with overall survival in patients with nonmetastatic clear cell renal cell carcinoma treated with nephrectomy” which was published in your journal, with great interest. This study’s findings indicated that mean platelet volume-to-lymphocyte ratio (MPVLR) is an easily obtainable prognostic marker for overall survival in patients with nonmetastatic clear cell renal cell carcinoma treated with nephrectomy. We would like to make some comment on this study.

There are major limitations about mean platelet volume (MPV) levels in this study;

  1. (1)

    In this study, MPV measurement technique is not written. Pre-analytical variables, such as the anticoagulant used, and the time between blood collection and measurement are known to significantly affect MPV measurements. Although EDTA is traditionally used and recommended for samples destined for blood counting it is well known that platelets collected into EDTA anticoagulants undergo time-dependent platelet swelling and activation [2, 3]. The retrospective nature of the study leads to a significant problem because the MPV results could not be standardized.

  2. (2)

    The exclusion criteria of this study are insufficient. There are many diseases (such as hypertension, obesity, coronary heart disease) and medications (such as anticoagulant therapy, statins) affecting to MPV levels [4].

  3. (3)

    This study is retrospective and its duration is 10 years. However, recent studies have shown seasonal changes in MPV levels [5]. On the other hand, different devices and technologies used in MPV measurements can produce deviations [6].