Plateletcrit May Not be a Marker for Recurrent Pregnancy Loss

We read with a great interest the article of Aynioglu et al about plateletcrit (PCT) and recurrent pregnancy loss (RPL). We would like to comment on this study. Firstly, the authors suggested that methylenetetrahydrofolate reductase (MTHFR) gene mutations were the most common hereditary thrombophilia for thrombosis in pregnancy. However, Leiden Multiple Environmental and Genetic Assessment (MEGA) study which performed on 4375 patients with venous thrombosis or pulmonary embolism and from 4856 controls showed no association between the common MTHFR 677CT polymorphism and venous thrombosis. According to the results of other studies, MTHFR mutations do not seem the predisposing cause of venous thromboembolism in either or no pregnant women, too. Thus, the American College of Obstetricians and Gynecologists and the Royal College of Obstetricians and Gynecologists do not recommend assessing MTHFR polymorphisms for evaluation of etiology of thrombophilia for venous thromboembolism in pregnancy. Secondly, the authors alleged that mean platelet volume (MPV), platelet distribution width (PDW), and PCT are predictive for platelet aggregation. Now, platelet indices are not used as platelet function tests. Turbidometric platelet aggregometry is the gold standard test for platelet functions. Platelet indices do not correlate with optical platelet aggregation responses usage with turbidometric platelet aggregometry. Moreover, Beyan et al found that severe platelet aggregation abnormalities were absent in patients with RPL. Additionally, PCT does not predict more than MPV. Determinations of complete blood count were done using a Beckman Coulter LH 780 analyzer (Beckman Coulter, Miami, Florida) in this study. According to operator’s guide of this analyzer, PCT and PDW parameters are derived parameters and are for research use only. They should not be used in diagnostic procedures. The MPV is measured directly from analysis of the platelet distribution curve, and PCT is calculated according to the following formula: PCT 1⁄4 platelet count MPV/10 000. So reliability of PCT is directly related to MPV. Another critical issue is that MPV has technological limitations and variations in measurement procedure. Platelet size progressively increases with time using EDTA as an anticoagulant. Jackson and Carter notified that MPV increased up to 30% within 5 minutes of exposure and further by 10% to 15% over the next 2 hours. Lance et al presented that timing was important when measuring MPV and optimal measuring time with EDTA should be 120 minutes after venipuncture. Because the measurement time of samples was unknown in this retrospective study, reliability of data was questionable. As a result, PCT may not be a marker for RPL.