The complete blood count: data or clinical information?

Harmonization in laboratory medicine is increasingly recognized as a fundamental requirement to ensure interchangeable laboratory information, avoid confusion among users, and ultimately improve patient safety. However, current evidence continues to highlight substantial gaps in harmonization across several dimensions of the total testing process, including test requesting strategies, analytical comparability among different methods and platforms, reporting units, reference intervals, and the clinical interpretation of results. The complete blood count (CBC) represents a paradigmatic example of the persistent lack of harmonization in laboratory medicine and of the potential clinical implications that may arise from it. The CBC is among the most widely requested and clinically impactful laboratory tests, being routinely used across nearly all areas of medical practice. However, recent papers published in highly influential medical journals, including Nature and JAMA, have highlighted two complementary but equally important issues. On the one hand, these studies emphasize the need for improved interpretative criteria, particularly through the adoption of personalized reference intervals that better reflect individual biological variability. On the other hand, they underline the substantial heterogeneity in the number and type of CBC parameters reported, which may generate uncertainty and confusion among clinicians regarding the clinical meaning and utility of the reported variables. Taken together, these observations highlight that harmonization should not be limited to analytical standardization alone but must also address the appropriateness of test requesting and the clinical interpretation of laboratory results. In this perspective, CBC may represent an ideal model for rethinking the role of laboratory medicine: moving from the simple generation of numerical results toward the delivery of actionable and clinically meaningful information. Achieving this goal requires stronger collaboration between laboratory professionals and clinicians, with the shared objective of aligning test requesting, reporting strategies, and interpretative criteria to the clinical question and the patient's context. Such an approach would represent a concrete step toward the implementation of Value-Based Laboratory Medicine, where the true value of laboratory testing is measured not by the volume of tests performed but by its ability to improve diagnostic accuracy, support clinical decision-making, and ultimately enhance patient outcomes.