Reference intervals for platelet indices using Sysmex XT-1800i in Egyptian population
Noha H Boshnak
Background: Platelet indices have been receiving attention recently as clinically valuable biomarkers. However, these indices are influenced by many factors such as ethnicity origin, age, gender and the type of technology used in measurement. Hence, determination of method-specific reference interval with regards to age, gender and ethnic base has been recommended. This study aimed to define reference intervals for platelet count and indices for medical research and practice. Method: Blood samples were collected from 380 healthy adult who underwent routine medical checkup. The study population consisted of 184 male and 196 female. Their ages ranged from 16 to 82 years with median age of 52 years. Samples were analyzed using Sysmex XT1800i. The platelet count and indices were recorded. The median values of each parameter were compared after stratifying the samples according to gender and then according to age. The reference intervals were presented as 2.5 and 97.5 percentile. Results: There were significant gender based differences for platelet count and indices. Therefore, separate reference intervals for the two genders were defined. The reference intervals for each parameter were as follows: platelet count, 158.0 - 387.0 ×109/L for females and 169.2 - 324.7 ×109/L for males; platelets distribution width (PDW), 10.0 - 16.9 fL for females and 10.4 - 15.9 fL for males; mean platelets volume (MPV), 9.3 - 12.2 fL for females and 9.5 - 11.8 fL for males; platelets -large cell ratio (P-LCR), 20.0 - 42.3% for females and 21.6 - 39.0% for males; plateletcrit (PCT), 0.18 - 0.41% for females and 0.18 - 0.34% for males. When we categorized the patients according to age we didn't find significant difference except for platelet count and PCT (P < 0.001). Weak, but significant correlations were found between age and each of platelet count and PCT. Negative significant correlations were observed between platelet count and each of PDW, MPV and P-LCR, while positive correlation was found between platelet count and PCT (P<0.001). The PDW was positively correlated with each of MPV and P-LCR. Conclusion: The reference intervals obtained in this study differed from the previously established reference values. Gender differences that have been observed are worthwhile. Therefore, this study validate the principle that it is essential to determine local reference intervals, taking into consideration the gender differences, since it reflects the population for which the test will be applied for better clinical interpretation and proper intervention.