Retrospective Analysis of Inflammatory Biomarker Patterns and Platelet Dynamics in Hospitalized Adults

Background: Systemic inflammation is common in hospitalized adults and may arise from infectious or non-infectious conditions. Several biomarkers, including WBC, neutrophil count, CRP, PCT, IL-6, and NLR, are widely used in clinical practice but may provide non-equivalent clinical information. Platelets are active participants in inflammatory responses, yet relationships between inflammatory biomarkers and platelet dynamics in hospitalized populations remain incompletely characterized. Methods: This single-center retrospective study included 321 hospitalized adults between December 2024 and December 2025. Baseline biomarkers included WBC, absolute neutrophil count, platelet count, CRP, PCT, IL-6, and dNLR, analyzed according to availability. Spearman correlation assessed biomarker relationships. Infection-related and non-infectious diagnoses, classified using primary clinical diagnoses and available clinical documentation, were compared using the Mann–Whitney U -test. Longitudinal associations between inflammatory changes and platelet dynamics were evaluated using changes during hospitalization. Results: WBC and neutrophil count were strongly correlated (r = 0.95, p < 0.0001). CRP was moderately correlated with PCT (r = 0.34, p = 0.002), and PCT was positively correlated with IL-6 (r = 0.55, p < 0.001). Age was not significantly associated with CRP (r = − 0.12, p = 0.153) but showed a modest correlation with dNLR (r = 0.165, p = 0.003). CRP, PCT, and IL-6 were higher in infection-related diagnoses than in non-infectious conditions (all p < 0.05). In longitudinal analyses, increases in PCT were associated with decreases in platelet counts (r = − 0.45, p < 0.0001), while CRP showed a weaker inverse association with platelet changes (r = − 0.21, p = 0.034). Conclusion: Inflammatory biomarkers in hospitalized adults demonstrated heterogeneous correlation patterns consistent with partially distinct inflammatory responses rather than a single uniform inflammatory signal. Leukocyte-based markers and cytokine-associated biomarkers represented partially independent components of systemic inflammation. Dynamic increases in inflammatory activity were associated with platelet decline during hospitalization. Keywords: inflammatory markers, infection, procalcitonin, C-reactive protein, derived neutrophil-to-lymphocyte ratio, platelet count