Diagnostic methods in medical sciences (i.e. laboratory hematology testing) is an essential part of the decision-making process, wherein results of laboratory testing often influence diagnosis and treatment of a variety of hematology disorders. We have read with interest the article by Klop et al. where the authors address important aspects of preanalytical variability as regards the postprandial period. Preanalytical variability, including biological variability and patient preparation (i.e. adequate fasting time before blood collection) is still an important source of variability in laboratory testing. Therefore, the preanalytical phase actually represents the most critical area to target for achieving major improvements in the total quality of laboratory diagnostics.